Training[1]

SDH Basics Training

Manual

Course ID : 50054 228

Mr. S.R.Joshi Prepared by

Mr. S.R.Joshi

Mr. S. Ghoshal

3rd Dec. 2007

Reviewed by

Approved by

Release Date

RCLC Learning Centre, (ISO 9001-2000 Certified) D-Block, 1st Floor, Wing 6, DAKC, Navi-Mumbai, 400709, India. RCLC-GEN-042

1

Issue No.

Rev No

Revision Detail

Revision Date

Revised By

Checked By

Approved By

D

Addition of slides-addition in explanatory notes –for easy understanding

03 – 12 - 07

S.R.Joshi

Kenneth

S. Ghoshal

Released for Training

03 – 12 - 07

01

Vendor courseware detail : Vendor : Vendor Category

SG / IG / LG / RD

Best Suited for

Version/ Issue : D Date :

L1/L2/L3/L4 /Others (specify)

Comments

Fundamentals

Course ID

Course code : 50054 228

Issue No :

RELEASED FOR TRAINING

Module Name

Prepared by

Volume :

-

Rev No : E

Rev dt: 03 – 12 - 2007

Of

S.D.H.

Course Code Reviewed by

S. R. Joshi

50054 228 Approved by

S.R.Joshi

ISO 9001– 2000 Certified

L3

L4

Suitable for

L1

Module

TRANSPORT ENGINEERS OPERATION & MAINTENANCE TRAINING

FEO

Course No.

RELIANCE COMMUNICATIONS

Date

GET

Others

Doc. No.

01

Rev. No.

02

Rev dt

06- 09 - 07

21- 12 - 03

Comments

TECHNICAL TRAINING DEPARTMENT

Prepared by

Shailesh Joshi

Location

Checked by

Shailesh Joshi

Approved by

S.Ghoshal

D-Block, 1st Floor, DAKC, N.Mumbai

Contact: Shailesh Joshi Ph 303-83098,RIM 93222 15762 [email protected]

S. Ghoshal

D-block, 1st Floor, Wing 6, DAKC Navi-Mumbai 400709, India

RIC-Learning Centre

L2

Release Dt: 03 – 12 - 2007

2

†

Far End … … … … …

†

Keep mike off unless Q&A session Keep NetNet-meeting ON Post offline questions on Chat Ppt. & trainers are seen simultaneously Report discomfort immediately

Near End …

†

Points to remember!

Give first chance to far end

Both Ends … … … … … …

Keep courseware ready for reference Raise hand, identify yourself, ask question Keep mobiles off/ silent Avoid leaving/ joining the class in between Stick to break timings ASK QUESTIONS

3

Learning Objectives On successful completion of this course the participants would be able to Describe following topics : 1. The role of Transport in telecom network 2. Facets of Transport 3. Media – Wireless – wire line Copper - OFC 4. OFC – Optic pulse propagation by TIR – Losses & Computation – Dispersion 5. Topology – Star & Ring 6. Technology PDH - Analog Digital Conversion - PDH transmission & it’s limitations - Mapping PDH payload into SDH frame 7. Technology SDH - Multiplexing hierarchy - Concept of Virtual Container - Lower and Higher order Path Overheads & Pointer - STM -1 Transfer Module – JKLM Numbering. - Regenerator section & Multiplexer section & Overheads 8. Protection Techniques - Dedicated & Shared 9. Time Synchronization - Quality level – Atomic & GPS clocks. 10. Network Management 11. Operation & Management – Layered Alarm Surveillance.

4

REVIEW OF COMMUNICATION SYSTEMS ( Module 1 )

5

Model of Telecom - Transport Operation Support Systems

Transport Switch

Switch

Access

Access

Services

Signaling Access

Access

Generally all Telecommunication system can be modeled with a few basic blocks: 1. Access A means to connect to users, convert their talk into electronic signals and vice versa. Access equipment would mean how easily and reliably the customer gets a connection. 2. Switch A means to connect A to B while there are a thousands other connections between A to Z possible. Switch would mean how many subscribers can be connected. 3. Transport A means to carry traffic & signals between several switches & also between switch & access equipment. It also means ,what bandwidth he gets (how fast does he download), 4. Services: like Caller ID - SMS – Call diverting-Call forwarding –voice mail-sms, wake-up call, call debar, Auto answering - R world – On line flight / railway ticket booking – getting a flight boarding pass -, Operation support system that’s what network operators need to operate their networks efficiently and effectively. 5. Signaling: Analog to railway transport - Train has left at this particular time – if any problem /path failure-conveying to HQ. In case of link failure, which alternate path to be followed. And finally OSS decides how efficiently you run the network, repair faults, raise correct bills, etc. 6

Reliance Confidential

Challenges of Transport

Voice

Video

More User, more usage

More Bandwidth

More Flexibility

More options

More Reliability

Data

More Uptime

In modern telecommunication, there is an increasing realisation that Transport is as important as building block - as any other like Switch or Services. Transport has traveled it’s distance from being merely the physical connectivity to being an performance enabler. Why is that so evident today. Because as technology evolves, there is increasing demand for: 1. More & more bandwidth - can we give new connections as & when required –no waiting time –no limit More users, more frequent use, - availability of unlimited talk time without system getting hunged – more frequent use - more information & data to be carried, so more bandwidth. 2. More flexibility: - Can we have voice & data & video on the same line, at the same time, - Can we get more download speed with increasing uploading speed, - Can we provide 100 or 500 number in a sequence (corporate connections) 3. More Quality & Reliability -Mere transmission is not good enough, quality of voice or video is also important, - Reliability of service – Uninterrupted continuous service for 24 hrs & 365 days / year. Our MTTR should be measured in minutes & not in hrs.-Availability of Protection path - Can we reduce waiting time to zero – i.e operator should not say – You are in the Queue for STD or Local calls - i.e. at Hospital or Hotel – should not say Come tomorrow - i.e. can we provide the service as & when required?-

7

Facets of Transport 1. Media •

Wireline

Copper , Aluminium

• •

Wireless Optical

RF, μW ( Electromagnetic) OFC

2. Topology - (Pattern of connecting

network element) Mesh - Local – Nx(N-1) links 2 Star Bus - for LAN Ring -

-

3. Technology - Voice Communication - Modern Transport

PDH

SDH, DWDM

4. Network Management -

Network Management

Preside

Main Pillars of Transport MEDIA - Electromagnetic – Frequency generated & broadcasted by BTS (870MHz ) is greater than Frequency generated & broadcasted by Mobile unit (825MHz).so it gets synchronized with that of mobile – resulting in Wireless transmission.

Technology Token Ring – Ring in which only one circulating Token - Token holder can speak , others are listners only –If token holder do not want to use, he has to pass it to next fellow in the ring. Ethernet – LAN - Network on smaller scale – Commercial complex-e.g.DAKC IMT – Integrated mobile terminal e.g. FWT.

Network Management – A ) Local Craft Terminal – Local panel through which nearby Mux are controlled - e.g in Lab. we are controlling 4 transport equipment through Laptop / Desk top B) Hyper Terminal - Dumb terminal – softwear through which response from the Mux can be received. c) Network management – All Mux & CT ( control terminal) in the network ( large scale ) can be

controlled by SERVER at NNOC. 8

MEDIA Module 3

1) Light travels in OFC-multiple Reflections just like rebouncing of a ball. 2) Transmitter-EMW-Elect-Digital , Receiver = digital – Elect.- EMW 3) TIR = angle > Critical Angle

& n1 > n2

4) OFC – Costruction – specification = core dia. / cladding dia.- comparisson with hair, 5) Useful Wavelength lie in Infra Red region i. e. 850 λ,1310 λ ,1550 λ 6) Losses : Absorbtion ά 1/ λ , Scattering ά 1/ λ4 7) Loss = dB = -10log10 (P2/P1)

& bending ά λ

POWER = dBm = -10log10 (P /1mw )

8) Types of Cables – (a) Material based (b) Mode based (c) refractive index based 9) Dispersion – multimode – Chromatic At R COM – dia. Reduced (SM) & step index reduces Chromatic disp. 10) G 652 - 0 disp. At 1310 – used at Access route - DWDM – 32 λ x 2.5 Gb at 1550 11)

G-653 - 0 disp. At 1550

12)

G-655 – 0 disp. above 1550 –

NLD / Inter circle – DWDM – 80 λ x 10Gb at 1550

9

Wireless Media Transmission Systems µW Radio 155Mbps(STM-1) 50km / 500km Terminal

Terminal

Higher order multiplexer

Higher order multiplexer

Satellite 400Kbps 3000km

Satellite dish

Satellite dish

Optical fiber cable OFC

µW & Radio It is necessary that antenna should be visible to each other.e.g. Antenna located at top of the hill &2nd at the ground level. Satellite When antennas are not visible to each other then we require to use Satellite transmission e.g. transmission fro Chennai to Andaman Nicobar Island

10

Optic Fiber Cable (OFC) Module - 4

The advantages of an Optical Fiber are mentioned above. Advantages of Optical Fiber Distance:- The extremely low losses of modern telecom grade fiber enable distances of 50-100Km between repeaters to be routinely achieved. Capacity/Bandwidth:- The information carrying capacity of optical fiber can be enormous. G-652 has capacity 2.5Gbps/fiber/wave length. it/sec can provide the equivalent of 30,000 individual telephone signals of 64kbit/sec and G-655 has capacity 10Gbps/fiber/wavelength (1000Gb/sec is now very close to being achieved). Security:- Optical fiber systems do not radiate any signal, and hence have almost total immunity to ‘wire tapping’. It can be done but is very difficult unless access to splices or connectors is possible. Immunity to Noise:- The glass optical fiber is a dielectric rather than a metal and thus does not act as an antenna in the way metal conducting elements do. The fiber will not, therefore suffer from inductive interference such as ·

RFI Radio Interference - EMI Electromagnetic Interference - EMP Electromagnetic Pulse.

This effective immunity to interference makes it possible to use fibers alongside or even on power lines. Long Life:- Fiber does not corrode like metal conductors. Light Weight:- Optical fiber is remarkably light in weight. A 10Km stand of telecom grade fiber on a shipping spool weighs less than 2kg whereas a 500m reel of co-ax copper cable weighs 30kg. Environmentally Friendly:- Manufactured from the most abundant material in the earths crust. Comparatively small amounts of raw material are required therefore energy, transport and process costs are reduced. By using fiber for communications the world’s copper reserves are saved for other purposes. Future Proof:- Maybe yes –maybe no. It is impossible to know, however the signs are encouraging. It lasts a long time –we only use a small amount of its theoretical capacity—as a result it is probably fair to say that fiber provides our most future proof transmission medium.

11

Journey through the “Optical Tunnel”

if we get a optical tunnel where once a light pulse enters at one end can only come out at the other end, would serve our purpose. Well an OFC is just that. Transmission through a OFC is like light ball traveling down a tunnel. It reflects several time time on the “wall” before reaching the end of the tunnel.

Train

travels on railway track

transfers the Passengers

Wavelength

travels on OFC

transfer the Data / voice / video

Advantages of OFC over other media like Cu wire are: 1. Very low attenuation-Loss depends on length only –free from amount of data transmitted 2. No Electromagnetic Interference (EMI) 3. No Bandwidth-distance relation, hence enormous large bandwidth available.-10Gbps whereas Capacity of Cu wire is limited i.e. 34 Mbps. 4. OFC are far thinner in diameter.-smaller in size-light in weight. 5. Greater safety as difficult to join-High security. Disadvantages are 1. OFC is costlier than Cu-wire. 2. OFC is fragile. 3. OFC are difficult to join. 4. OFC has it’s own set of losses – dispersion, absorption, etc. 12

†

An optical fiber is made of three sections: …

…

…

Fiber Geometry

The core carries the light signals i.e.Optic Pulse travells in core only The cladding keeps the light in the core serves the purpose of Compound wall

Core (7 – 62.5 µm)

Cladding (125 µm)

The coating protects the glass

†

Fiber dimensions are measured in µm -6 … 1 µm = 0.000001 meters (10 ) … 1 human hair ~ 50 µm

†

Refractive Index (n) … n=c/v … n ~ 1.468 … n (core) > n (cladding) … c = 3 x 10 8 Meter / second

Coating (245 – 250 µm)

Core: The core of an optical fiber – is a glass rod - denotes the central part of the fiber where the majority of the light propagates. Cladding: The cladding of an optical fiber surrounds the core and has a Refractive Index lower than that of core. This difference in refractive index allows total internal reflection to occur within the fiber core. & avoids the entry into the Cladding .Total internal reflection is the phenomenon by which light propagates in optical fiber. Coating is made up of PVC material-available in different colours as per ITU code

13

Optical Fiber

Specifications

14

n1sinA1 = n2sinA2

Snell’s

Law

Critical Angle: Sin φ Critical = n2 / n1 Medium - 1 A1 n1

n1 > n2

A

n2

A2

As A1 increases A2 also increases. At particular value A2 becomes 900 . A is called

Medium - 2

A,

critical angle

i.e. No light enters material 2

At any angle of incidence greater than ‘A’ all light will be reflected back to material 1.

Snell's law is defined as : n1 sinA1 = n2 sinA2 (“Law of Sines” - by Descartes ). Where n is the refractive index and A is the corresponding angles as shown. The refractive index is the ratio of the speed of light in a vacuum to the speed of light in a given medium. Where C = Velocity of light in Vacuum I.e. 3* 108 metrers per second. n1 = C / V V = Velocity of light in a given of that medium So, if the Upper part of the diagram is CORE & n1 is Refractive Index of the Core material and if the Lower part is Cladding , n2 is Refractive Index of the Cladding material. when light passes from one medium to another, the angles & refractive indexes of the media determines the path that light will take. The phenomenon of total internal reflection was discovered by John Tendel in 1854, when he filled a can with water , which had a hole at the lowest level. Obviously water started flowing out of the hole forming a curved projectile path. As Tendell lit a torch at the top of the Can, a portion of that light would come out of the hole at the bottom. These light rays then experience total internal reflection because Refractive Index (n) of water is greater than air. Thus these rays would bend along with the watery projectile path giving rise to the idea that light could travel in a curved path if the phenomenon of TIR is repeated many times.

15

Propagation Of Light In Fiber

When a ray of light is incident at an angle greater than the critical angle, it gets completely reflected back to the same material. This is called TOTAL INTERNAL REFLECTION Communication Through Fiber Uses This Principle.

Total internal reflection: Total internal reflection is the phenomenon by which an optical fiber guides light. If light incident at any angle more than the Critical Angle at the interface between the core and cladding (Refractive index of Core > Refractive index of Cladding ) such that it will be entirely reflected back in the Core (none is transmitted into the cladding where it is lost). The critical angle depends on the material of core and the cladding. It can be summarized that the important concept of fiber optic communication technology is: When light travels from a medium with higher refractive index ( Core) to a medium with lower refractive index ( Cladding )and if it strikes the boundary at an angle more than a critical angle, all light will be reflected back to the incident medium (Core). This phenomenon is known as total internal reflection.

16

Optical UV

†

Visible

Spectrum

IR

λ

850 nm 980 nm 1310 nm Communication wavelengths …

850, 1310, 1550 nm

…

Low-loss wavelengths Light

…

Ultraviolet (UV)

…

Visible

…

Infrared (IR)

1480 nm 1550 nm 1625 nm

Velocity = c =ƒ x λ

λ (nanometers) Frequency: ƒ (tera hertz)

Wavelength:

1 Nena meter = 10 -9 meter

1 Pica meter = 10 -12 meter

The Optical Spectrum can be divided into three regions. Ultra Violet: That portion of the electromagnetic spectrum in which the longest wavelength is just below the visible spectrum, extending from approximately 4 nm to 400 nm. Visible Light: Electromagnetic radiation visible to the human eye; wavelengths of 400-700 nm. Infrared (IR): The region of the electromagnetic spectrum bounded by the longwavelength, extreme of the visible spectrum (about 0.7 µm) and the shortest microwaves (about 0.1 µm). To generate different wavelength Now a days - Plug gable Lasers for of different Frequency are available In the old days Diff. Cards were available for diff. Frequency

17

Attenuation - ( Losses ) †

Loss is the measure of the reduction in signal magnitude, or loss of power of a optic pulse, along a length of fibre. It is expressed as Decibel ( dB )

†

When the loss is described per km, it is known as Attenuation. (i.e. dB/km) at a specified wavelength.

†

Attenuation depends on length of a fiber & also on Link components like splice Joints - connectors etc.

Attenuation describes how energy is lost or dissipated. Loss is the cost of moving something, like charges or particles or light pulses. Attenuation / Losses are due to - Impure- non uniform material , joints i.e. Splicing Attenuation in fiber optic cabling is usually expressed in decibels per unit length of cable (i.e. dB/km) at a specified wavelength. Attenuation = 10log10(Iout / Iin) Where, I out = outgoing intensity (intensity is measured in Watt/.m-2 ) I in = ingoing intensity (Watt/.m-2 ) Research & Developement 1980 – 100dB / km 1990 – 6dB / km 2005 – 0.18 dB / km

18

Sources of Attenuation in Fibers Absorption – Caused by impurities in the glass, and any atomic defects in the glass increases dramatically above 1700 nm. The peak absorption occurs at approx.1400nmλ - proportional to 1 / λ

Scattering – Scattering is caused by small variations in the density of glass . Loss of optical energy due to imperfections / in homogeneities (localized density variations). And therefore act as scattering objects. - proportional to 1 / λ4

Geometric Effects -

proportional to λ

Bending losses increases with increase in Wavelength. Effects of 2 cm radius bend at three wavelengths - 1310 nm = < 0.1 dB loss 1550 nm = 2 dB loss 1625 nm = 6 dB loss

19

Graph of Loss v / s Wavelength Attenuation varies with the wave length of light. The fiber exhibits minimum attenuation at wavelength slots 1310nm, and 1550nm . (nm = 1/ 1000,000,000 Meters) These are called second window and third window. First window 850 nm was used earlier days when laser diodes were available only at that wavelength

Loss in db/km

5 4 3

1400 nm 2 1

0

800

850

1000

1310

1550 1600

Wave length

Scattering and Absorption decides suitability of optical fiber for transmission at specific frequencies only. If a graph of Loss in dB/km is plotted against the wavelength then we observe that, ‘Attenuation varies with the wave length of light.’ The fiber exhibits minimum attenuation at wavelength slots, 1310nm, and 1550nm . These are called, second window and third window. Note: The second and the third windows are in practical use today. We don't use the 850 nm any more except for some restricted applications. The 850 nm was in use in the past when the Laser Diodes available were of 850 nm only. 1550

1310

Optical Equipment

Costly

cheap

Attenuation dB/Km

0.18 to 0.3

0.3 to 0.5

Chromatic Dispersion ( C.D.) –ps/nm/km

More then 16 Ps/nm/km

Less then 3.5

By using NZDSF-C.D. 1525 to 1565

4 to 6 ps/nm/km

1565 To 1630

6 to 10 ps

If G 652 is used for long dist,then we shall require to use more Regenerators-it will degrade the clock more. – resulting in bit error

20

Losses - Attenuation in Optical Fiber - dB

Pout/Pin in mw)

(P

dB

Pout/Pin (P in mw)

dB

1

0

1.1

0.4

2

3

1. 25 =(5/10)x(5/10)x 5

7-10+7-10+7 = 1

3

4.7

1.6 = (8/10)x2

9 -10 + 3 =

4 = 2x2

3+3 = 6

0.5

-3

5 = 10/2

10-3 = 7

0.66

-2

6 = 3x2

4.7+3 = 7.7

¼ = o.25

-6

7 = 49* = (10x5)*

½ (10+7) = 8.5

AxB

a+b

8 = 2x2x2

3+3+3 = 9

A/B

a-b

9 = 3x3

4.7+4.7 = 9.4

A1/2

a/2

10

10

A 1/3

A/3

2

21

Power in Optical Fiber- in - dBm • RF and Optical powers are measured in dBm. • 1 mW is taken as a reference power • All other powers are expressed as ratios relative to 1mW • When the power is less then 1 mw –it’s dBm value will be Negative

dBm = 10log 10 ( P in mW / 1mW) To find dBm value for 5mw power (i.e. ratio = 2) dBm = 10log10 ( P in mW / 1mW) = 10log10 (2 mW / 1mW) = 10 log10 ( 2) = 10 x 0.3010 = 3.010 = Say 3 If Power = 2 mW If Power = 5 mW If Power = 7 mW If Power = 10 mW If Power = 500µW If Power = 200µW If Power = 100µW If Power = 80µW

then it is expressed as then it is expressed as then it is expressed as then it is expressed as then it is expressed as then it is expressed as then it is expressed as then it is expressed as

3 dBm 7 dBm 8.5 dBm 10 dBm -3 dBm -7 dBm -10 dBm -11 dBm

In the RF Industry and in optical transmission power is measured relative to 1 mW and expressed as dBm 0dBm is taken as the reference power to which all power in field situations is compared. In The Broad casting industry 1KW is taken as the reference power If you work with voltages in the audio field 1V line voltage is taken as the reference voltage and 1v is referred to as 0dBV

22

Losses in dB & Power in dBm †

†

Losses -in the fiber link-at the connectors-at splice joints is measured in dB dB = 10log10 ( P out / Pin) Attenuation is the losses described per km,

Input power ( Pin )

Fiber link loss

Output Power (Pout )

Length

†

† † †

Optical powers and RF are measured in dBm. dBm = 10log 10 ( P in mW / 1mW) 1 mW is taken as a reference power All other powers are expressed as ratios relative to 1mW When the power is less then 1 mw –it’s dBm value will be Negative

23

Ex. 1 A :

Attenuation in Optical Fiber

For the fiber link shown below. (1) Input Power = 2 mw (2) Link Loss = 13 dB (3) Link Length = 50 Km

Input power (P1) = 2

MW

Fiber link loss = 13dB

Output Power (P2)= ?

50 Km

Find: (a) Attenuation per Km.=

(b) Output Power in dBm =

24

dbm (Power) & db (Attenuation) computation Exercise -1B

For the above please calculate the following: Receiver Power in dB

= Transmitter power - Losses

=

Pout/Pin (P in mw)

dB

Pout/Pin (P in mw)

dB

1

0

1.1

0.4

2

3

1. 25 =(5/10)x(5/10)x 5

7-10+7-10+7 = 1

3

4.7

1.6 = (8/10)x2

9 -10 + 3 =

4 = 2x2

3+3 = 6

0.5

-3

5 = 10/2

10-3 = 7

0.66

-2

6 = 3x2

4.7+3 = 7.7

¼ = o.25

-6

7 = 49* = (10x5)*

½ (10+7) = 8.5

AxB

a+b

8 = 2x2x2

3+3+3 = 9

A/B

a-b

9 = 3x3

4.7+4.7 = 9.4

A1/2

a/2

10

10

A 1/3

A/3

2

25

Classification

†

Refractive Index Classification

†

Mode Classification

Of

Fibers

. .

26

Refractive Index classification - Step Index Fiber

•

Core Has Uniform Refractive Index. A Sharp Step In Core And Cladding Junction.(n1 to n2)

•

Used for minimising Chromatic Dispersion

27

Refractive Index classification - Graded Index Fiber

•Ref. Index Of Core Is Not Uniform rather Gradually Decreases Radially Outwards . Used for minimising MODAL Dispersion

To compensate for the dispersion drawback of step-index multimode fiber, gradedindex fiber was invented. Graded-index refers to the fact that the refractive index of the core is graded—it gradually decreases from the center of the core outward. The higher refraction at the center of the core slows the speed of some light rays, allowing all the rays to reach their destination at about the same time and reducing modal dispersion.

28

B - Mode Classification Multimode fiber (MM) †

Light travels in diff. Path Core diameter varies - 50 to 62.5 µ-meter

†

Mode Depends on - Wave length ( ↓ ) -

†

† † †

Single mode fiber (SM) † † † † †

n2

Cladding

Core dia. ( ↑ ) - Refractive Index n1 & n2. Modes do not depend on Length of Fiber. n1 Primarily used for intra-office application Equipments & cables are less expensive than single mode .

Only one mode (ray) propagates Light travells in Only one Path / mode. Core diameter is about 7-9 micro-Meter. Primarily used for long dist.. applications. Equipments & Cables required are costly

n2 n1

Cladding Core

λ1

λ2

Mode Classification: Multimode fiber: Multimode fiber allows multiple modes of light to propagate along its length at various angles and orientations to the central axis. Conventional sizes of multimode fiber are 62.5/125μm or 50/125μm. e.g. G-652- SM – for city network - of various make - like Corning (Germany) – Sterlite-RPG – Finolex – Tamilnadu Telecom Ltd (TTL) – BEOL (Birla Erricson Optical Ltd.) Conventionally, the size of a fiber is denoted by writing its core diameter and then writing the cladding diameter (Both in μm) with a slash between them. For example: 50/125μm fibers describe a fiber with a 50μm core and 125μm cladding diameter. Single mode fiber: A single mode fiber has a small core. Only one ray of light is expected to pass through. This highly parallel beam is incident along the axis of the fiber. Single mode fiber allows a single mode of light to propagate along its core efficiently. Conventional sizes of single mode fiber are 8/125μm, 8.3/125μm or 9/125μm.(core dia. / cladding dia). Single mode fiber allows very high-speed transmission. e.g. – G 655 – SM – for NLD – of various make – like Corning (Germany)Tyco ( USA) – OCC ( Farukowa-Japan) – OFS (USA)

29

Dispersion – eats your BW

Dispersion for G.655 - at 1550 nm – 18 pico seconds/ nm / km) - 18 ps / nm / km

Dispersion is the phenomenon of scattering of light due to tiny obstacles in the path of propagation. In OFC dispersion could occur due to impurity, heterogeneity of refractive index, etc. Dispersion causes light pulses to spread and thereby lose the binary status at some stage. Simply put higher dispersion could mean greater chance of losing information. Only means of negating that effect is to increase the pulse width. So we can conclude higher the dispersion lower would be the bandwidth.

30

What ƒ ƒ ƒ

is

Dispersion ?

Dispersion is the spreading or broadening (distortion)of light pulses as they propagate through the fiber. Dispersion is the change in shape of a propagating wavelet causing distortion Too much dispersion gives rise to bit-errors at the receiver (i.e., the inability to distinguish a 0 from a 1).

1 ? 1

1 0 1 Not recognizable

ƒ No-dispersion-shifted fiber (NDSF), - - - - - - - - - - 1310 λ - - -- - - G.652 ƒ Dispersion-shifted fiber (DSF),- - - - -- - -- - - - -- 1550 λ - - - - - G.653

ƒ Non-zero dispersion-shifted fiber (NZ-DSF), - - 1550 λ - - - - -- G.655 ƒ

Optimum dispersion at 1550 nm – 18 Pico second / (nm.km)

Dispersion is due to diff. Packets of light arriving at time,hence takes round shapecausing distortion i.e.Dispersion. Bandwidth of fiber is limited by dispersion. Dispersion increases in direct proportion to the square root of fiber length. NOTE: Bit rate (say ‘’data rate’’) is the number of bits that can be transmitted per second over a channel. It is measured in bit per second. It is the direct measure of informationcarrying capacity of a communication link or network for digital transmission. This is why it is also called information transmission rate. Bandwidth is the frequency range within which a digital signal can be transmitted without significant distortion. It is measured in Hertz (Hz). It is information carrying capacity characteristic of a communication channel used for analog transmission. These then are the two characteristics but obviously quite different. Bandwidth of fiber system is also limited modulation speed i.e. by the electronics. Ps/nm–km is the unit of dispersion. It is the slope of graph – travel time in 1 km of fiber. versus wave length of light Time to Travel 1 km of fiber

1310 nm 31

Modal Dispersion

†

A.

Modal Dispersion

Dispersion caused due to different paths the light rays take to travel from one end to the other. This is prominent in Multi Mode Fibers.

Optical Paths Modal

MMF (Step Index)

Difference Difference in inarrival arrival times times

Less zig – zag rays (lower order modes) travel a shorter distance. These correspond to rays traveling almost parallel to the center line of the fiber and reach the end of fiber sooner. The more zig-zag rays (higher order modes) take a longer route as they pass along the fiber and so reach the end of the fiber later. Chromatic Dispersion: Each wavelength of light travels through the same material at its own particular speed which is different from that of other wavelengths. For example, when white light passes through a prism some wavelengths of light bend more because their refractive index is higher, i.e. they travel slower. This is what gives us the "Spectrum" of white light. The "red' and "orange" light travel slowest and so are bent most while the "violet" and "blue" travel fastest and so are bent less. All the other colors lie in between. This means that different wavelengths traveling through an optical fiber also travel at different speeds. This phenomenon is called "Chromatic Dispersion". Now:- Total dispersion = Chromatic dispersion + Multimode dispersion Or put simply: for various reasons some components of a pulse of light traveling along an optical fiber move faster and other components move slower. So, a pulse which starts off as a narrow burst of light gets wider because some components race ahead while other components lag behind, rather like the runners in a marathon race. This spreads the wave and causes dispersion.

32

Graded Index Fiber – less dispersion

Graded Index fiber causes a series of continuous micro refractions for any ray that moves towards the cladding from the center of the core. This is because of the gradual change of RI from center of the core towards the cladding. Ultimately the ray of light experience TIR at a point where it’s incident angle is almost equal to 900 and thereby turn back towards the center. Secondly the speed of light is given as: V= C/N Where

V= Speed of light in a medium C = Speed of light in free space N = Refractive Index of the medium

Therefore as the ray of light moves away from the center of the core towards the cladding, it’s speed keeps increasing. And the speed keeps decreasing as it moves back towards the center. As compared to this a ray of light that travels through the center of the core all along will travel at the minimum speed (remember RI is highest at the center of the core). Thus the ray that took a longer path would travel faster and effectively take the same time to traverse the axial distance as that taken by the ray which was traveling through the center. Therefore in GI fiber although we find multiple modes, all the modes take equal time to travel thereby minimising the effect of modal dispersion.

33

Multi Mode Fiber • Multiple wave-fronts enter and propagate through the core • Different wave-fronts would take different time period to travel through the entire distance of the core. • This is because different wave-fronts are traversing different distances.

• Net effect is that a sharp square pulse gets distorted and spread out

There are two general categories of optical fiber in use today, multimode fiber and single-mode fiber. Multimode, the first type of fiber to be commercialized, has a larger core than single-mode fiber. It gets its name from the fact that numerous modes, or light rays, can be carried simultaneously through the waveguide. Slide shows an example of light transmitted in the first type of multimode fiber, called stepindex. Step-index refers to the fact that there is a uniform index of refraction throughout the core; thus there is a step in the refractive index where the core and cladding interface. Notice that the two modes must travel different distances to arrive at their destinations. This disparity between the times that the light rays arrive is called modal dispersion. This phenomenon results in poor signal quality at the receiving end and ultimately limits the transmission distance. This is why multimode fiber is not used in wide-area applications.

34

Chromatic Dispersion B. Chromatic Dispersion Dispersion caused due to the variation in velocities of different wavelength w.r.t the refractive index of the material. This is prominent in Single Mode Fibers. Refractive Index = n = c / v Where c = 3x10 8 meter/sec. & v = Velocity of light in that medium

i.e. v α 1 / n

Wavelengths λ Chromatic

SMF 2

λ1

Difference Difference in inarrival arrival times times

The difference in arrival times of the different components, would cause the broadening of the signal at the receiving end, the result being dispersion.

The Modal and Chromatic Dispersions can be visualized here. The difference in arrival times of the different components of the center wavelength (example: 1550 nm), would cause the broadening of the signal at the receiving end, the result being dispersion.

35

Chromatic

Dispersion

• Different frequency/ wavelength have different velocity of propagation • A single pulse would have several wavelengths • Each wavelength would travel at different speed • Thereby causing Chromatic dispersion

The effect of different RI is that different wavelength will travel at different speed: C, Speed of light in Free Space Speed of light (wavelength λ1) =

----------------------------------------RI of the medium for wavelength λ1

Thus even in a SMF, if the input pulse comprised different wavelength then it they will travel at different speed and thereby reach the end of the fiber at different times. Effectively there would be a small difference in time (few ps/km), if the input pulse wavelengths are separated by a few nm like in a LASER. Nevertheless this appear as dispersion, which can become significant in case of high BW signals.

36

FIBER DISPERSION CHARACTERISTICS G-652- NDSF - Good for short dist.(350 Km.) -High disp. Loss at 1550-

(DSF)- G653-Good for single channelFour way mixingCross talk-

Dispersion ps/nm-km

20

Wavelength 0

1550nm 1310 nm

1570nm

λ

Reduced Dispersion Fibers Non zero Dispersion Shifted Fibers (NZDSF) No Four way mixing-No cross talk

G.651: For completeness, we probably ought to mention G.651. This is a multimode fiber with a 50 micron core. It's not currently found much in telecom systems. G.652 is the original single mode fiber with a simple step-index structure. It has zero chromatic dispersion near 1310 nm It is Non Dispersion Shifted Fiber) and works very well at that wavelength. –Good for short distance application . (up to 350 km), But the fiber's lowest-loss wavelengths are around 1550 nm for long-reach systems . G.653: Dispersion-shifted fiber was developed to have best bandwidth &lowest loss at 1550. Zero chromatic dispersion was shifted up to 1550 nm to have the lowest losses in the fiber. The result? High-bandwidth, long-distance transmission operating in the 1550 nm window. But there's a catch: G.653 only works well for single-channel systems. The problem arises with G.653 in case of DWDM –because due to high power concentration in the fiber core, - generates nonlinear effects. i.e.four-wave mixing, occurs ,causing unacceptable cross talk and interference between channels. G.654 is a specialty fiber that was developed for subsea applications. It can handle higher power levels, having a larger core area, but usually also has high chromatic dispersion at 1550 nm. It is not designed to operate at 1310nm at all. G.655: This was developed as a fiber type that's optimized for long-haul DWDM transmission at wavelengths of around 1550 nm. It has a small, controlled amount of chromatic dispersion in the C-band – Between 1530 to 1560 nm, ( Zero dispersion at 1570 ) - where amplifiers work best, and has a larger core area than G.653 fiber. These characteristics solves problems of four-wave mixing - Cross talks and other nonlinear effects. This fiber type is known as non-zero dispersion-shifted fiber (NZDSF).

37

Optical Fiber Standards Designs of single-mode fiber have evolved over several decades. The three principle types and their ITU-T specifications are: • No-dispersion-shifted fiber (NDSF), G.652 9 Minimum dispersion at 1310 nm 9 Attenuation – Between 0.35 dB /km to 0.4 dB/km

• Dispersion-shifted fiber (DSF), G.653 9 Minimum dispersion at 1550 nm 9 Non-linear amplification for various wavelengths - without DWDM

• Non-zero dispersion-shifted fiber (NZ-DSF), G.655 9 Optimum dispersion at 1550 nm – 18 Pico second / (nm.km) 9Attenuation – Between 0. 18 dB /km to 0.21 dB/km. 9 Linear amplification for various wavelengths - DWDM

As optical fiber use became more common and the needs for greater bandwidth and distance increased, a third window, near 1550 nm, was exploited for single-mode transmission. The third window, or C band, offered two advantages: it had much lower attenuation (0.18 dB/km to 0.25dB.km.), and its operating frequency was the same as that of the new Erbium-doped fiber amplifiers (EDFAs- Amplifies the pulse in optical state only –doesn’t need to convert in elect. pulse.-Direct amplification). However, its dispersion characteristics were severely limiting. This was overcome to a certain extent by using narrower linewidth and higher power lasers. But because the third window had lower attenuation than the 1310-nm window, manufacturers came up with the dispersion-shifted fiber design, which moved the zero-dispersion point to the 1550-nm region.

Although this solution now meant that the lowest optical attenuation and the zero-dispersion points coincided in the 1550-nm window, it turned out that there are destructive nonlinearities in optical fiber near the zero-dispersion point for which there is no effective compensation. Because of this limitation, these fibers are not suitable for DWDM applications.

The third type, non-zero dispersion-shifted fiber, is designed specifically to meet the needs of DWDM applications. The aim of this design is to make the dispersion low in the 1550-nm region, but not zero. This strategy effectively introduces a controlled amount of dispersion, which counters nonlinear effects such as four-wave mixing (see the “Other Nonlinear Effects” section on page 2-11) that can hinder the performance of DWDM systems.

38

G. 652

FIBER

• Standard Single Mode Fiber-Step Indexed. • At Reliance 1310nm & 1550nm. band is implemented •1550 nm can support up to 32 Lambda wave lengths for DWDM •The bandwidth per lambda are limited to 2.5Gbps. • Total bit rate for 32 Lambda’s is 2.5 X 32Gbps. = 80 Gbps. • Good for Short haul applications up to 350 - 400Km and Metro regions. •This fiber is used for - City network – Access / SDCA routes •Make: Corning (Germany) – Sterlite - RPG – Finolex – Tamilnadu Telecom Ltd (TTL) – BEOL (Birla Ericson Optical Ltd.)

G.652: This is the original single mode fiber with a simple step-index structure. It has zero chromatic dispersion near 1310 nm and works very well at that wavelength. While this is fine for applications over moderate distances (up to 50 km), the fiber's lowest-loss wavelengths are around 1550 nm for long-reach systems - which complicates things somewhat. Incidentally, the current version of the ITU recommendation has three different grades of performance specified for different applications. At many places we are using wavelenth 1550 on Access route as the lenth is not much long e.g. G-652- MM – for city network - of various make - like Corning (Germany) – Sterlite-RPG – Finolex – Tamilnadu Telecom Ltd (TTL) – BEOL (Birla Erricson Optical Ltd.) The ITU-T initially standardized G-652 SMF which counts more than 80 million km of fibers installed in the world. e.g. G-652- MM – for city network - of various make - like Corning (Germany) – Sterlite-RPG – Finolex – Tamilnadu Telecom Ltd (TTL) – BEOL (Birla Erricson Optical Ltd.)

39

NZDSF

FIBER

G 655

• Non Zero Dispersion Shifted fiber (NZDSF) • Optimized to operate in the third window. : 1550nm • 10 Gbps can be supported per wave length. For DWDM total number of wave length supported is 80 Lambda. Total capacity = 10Gbps x 80 λ = 800Gbps • Good for Long haul applications - on NBB / NLD routes. • Make: Armoured – – Unarmourered – – –

Unitube black in colour - Corning (Germany) Unitube Tyco ( USA) Loose tube - ( Farukowa-Japan) Outer tube Green / Inner sheath Black Loose tube OFS (USA)

G.655: This was developed as a fiber type that's optimized for long-haul DWDM (Dense wave Division Multiplexing) transmission at wavelengths of around 1550 nm. It has a small, controlled amount of chromatic dispersion in the C-band (1530-1560 nm), where amplifiers work best, and has a larger core area than G.653 fiber. These characteristics combat the problems associated with fourwave mixing and other nonlinear effects. This fiber type is known as non-zero dispersion-shifted fiber (NZDSF). Armoured – Unitube black in colour - Corning (Germany) Armoured – Unitube Tyco ( USA) Unarmourered – Loose tube -OCC ( Farukowa-Japan)– Outer tube Green / Inner sheath Black Unarmourered – Loose tube OFS (USA)

NOTE: Large Effective Area Fiber (LEAF): An optical fiber, developed by Corning, designed to have a large area in the core, which carries the light. Lucent has developed True Wave Fiber for the same.

40

Fiber Colour Coding Colour – coding / Sequencing is important In a bunch of 12 fibers Colour sequence is maintained as given below as per ITU (International Telecommunication Union ) - code

BLUE

GREY

YELLOW

ORANGE

WHITE

VIOLET

GREEN

RED

ROSE

BROWN

BLACK

AQUA

Although not necessary, it is a good to memorize these.

41

Cable Construction Central strengthening member (Fiber-Reinforced-Plastic)

Loose tubes

Dummy tube Kevlar yarn

Filler - Jelley

Fibers

Polyethylene sheath Polyethylene jacket

The figure above shows the structure of a Loose Tube Cable. The construction shown above is a general type. It can withstand the temp. - 400 C to +700 C. Central strengthening member of Fiber-Reinforced Plastic is used to provide strength. It will protect against tensile load & also protect from damage due to bending. Jacket and Sheath: The outer, protective covering of the cable. Kevlar Yarn: Kevlar® is a very strong, very light, synthetic compound developed by DuPont which is used to strengthen optical cables, .Also used in mfg. of Tier & Bullet proof Jacket The loose tubes are surrounded by filler material like cellulose paper or bonded polyester for protection Dummy Tube: There may or may not be a dummy tube present. The dummy tube is not for providing extra strength, but to give proper concentricity to the cable. It acts as packing & restricts internal movement of loose tubes. The actual fibers are housed in the loose tubes. Jelly :The area surrounding loose tube is filled up with Jelly, which serves as Shock Absorber or Cushion against hammering blow & serves as Lubricant during the internal movement of tubes. Jelley also prevents water entry PRACTICALLY How to understand the technical specification: For example, G.652, SMF-28, CW1505x, NDSF - these terms could all apply to the same fiber. G.652 is an International Telecommunication Union (ITU-T) recommendation number; SMF-28 is a Single Mode Fiber with the manufacturer's (Corning) brand name; CW1505x is an example of a customer's (BT) specification; and NDSF (non-dispersion-shifted fiber) is a description of the product's distinguishing technical characteristics.

42

Cable - G.655

( N B B) BLUE

DUMMY

ORANGE GREEN BROWN GREY WHITE RED BLACK YELLOW VIOLET ROSE AQUA

Structure of 48 FIBER cable G.655 used in NBB route

This is the kind of cable used in the NBB (National Back Bone) route. It is a G.655 Cable with 48 Fibers in it. There are five tubes. One is a dummy tube, and the other four contain 12 fibers each, thus 12 (fibers) X 4 (tubes) = 48 (fibers in all). The color sequencing of 12 fibers in a tube is according to the ITU Specifications – mentioned above . The specifications and standardizations are setup by the International Telecommunications Union (ITU). Note: The color of the first tube is BLUE, second tube is ORANGE, and the other tubes are WHITE/NATURAL colored. International Telecommunications Union (ITU): A civil international organization, headquartered in Geneva, Switzerland, established to promote standardized telecommunications on a worldwide basis. The ITU-R and the ITU-T are committees under the ITU, which is recognized by the United Nations as the specialized agency for telecommunications. Visit: http://www.itu.int/home/index.html

43

Aerial Optic Fiber -ADSS

ADSS – All dielectric self supporting

44

WAVE LENGTH

MULTIPLEXING

MULTIPLE FIBER

OPTICAL MULTIPLEXERS

SINGLE FIBER

Large increase in Bandwidth can be achieved by using a technique called Dense Wave Division Multiplexing (DWDM). Suppose you had a one lane HW, only one vehicle can run at a time. If you needed more vehicles to run simultaneously you will have to add more lanes. Say 4 or 6 lane or you can construct multistory Highway In the above sketch , each lane is equated with diff. colour of light (violet, blue, green, yellow, orange, red, etc.) .When seven colours are passed through Trigular prism ,it becomes one ( Multiplexure theory) &when it will come out it becomes 7 colour again DWDM uses the above phenomenon, but uses Laser and IR light instead of visible light. The result is the same, only that we can multiplex many more wavelengths and demultiplex them at the receiving end. Normally we can achieve BW 10 Gbps with one wavelength, As per DWDM technology ,we can go up to 800 Gbps by using 80 Wave length! That too in a single fiber of OFC. And we have 48 cores in one cable and 6 such cables that can be laid in our NBB!! How much bandwidth ???? WDM (Wave length Division multiplexing) &FDM ( Frequency Division Multiplexing) is the same thing. WDM is measurable whereas FDM is not CWDM – Core Wave Division Multiplexing = less wavelength multiplexing. DWDM - Dense

= more wave length multiplexing

DWDM - 1530λ to 1563 λ = C band = Conventional 1570 λ to 1620 λ = L band = Long 45

DWDM Capacity with G 652 & G 655 G 652 † † † † †

1550 nm can support up to 32 Lambda wave lengths for DWDM The bandwidth per lambda are limited to 2.5Gbps. Total bit rate for 32 Lambda’s is 2.5 X 32Gbps. = 80 Gbps. Good for Short haul applications up to 350 - 400Km and Metro regions. This fiber is used for - City network – Access / SDCA routes

G 655 † † † †

10 Gbps can be supported per wave length. For DWDM total number of wave length supported is 80 Lambda. Total capacity = 10Gbps x 80 λ = 800Gbps Good for Long haul applications - on NBB / NLD routes.

46

ITU-T

WAVE LENGTH GRID - C Band Conventional

DWDM - 1565λ to 1625 λ = L band

DWDM - 1530λ to 1563 λ = C band = Conventional 1570 λ to 1620 λ = L band = Long

47

Module Review -

Exercise - 2

1.

Fours facets of Transport are ……………, ……………., ………….. and …………

2.

Number of modes in MM fiber depends on …..….., ……..….., …..…… & ……..….

3.

Single Mode have core diameter of …… to ….. Micrometer.

4.

For Multimode fiber core dia. varies from _ _ _ _ to _ _ _ _ _micrometer.

5.

G652 is SM / MM…, Step I / Graded I. used in _ _ _ _ _ _ _ route.

6.

G655 is _ _ _ _ ,

7.

Attenuation in OFC depends on ………………….…….. …

8.

The important wavelength 850λ , 1310 λ , 1550 λ lies in _ _ _ _ region of the spectrum.

9.

For Multimode fiber, the Optic Pulse travels in _ _ _ _ _ .

_ _ _ _ _ _ _ __

used in ……….………route.

10. The Cladding serves the purpose of _ _ _ _ _. 11. The fiber dimension can be represented as ratio of _ _ _ _ _ _ . 12. The Scattering losses are proportional to _ _ _ ___ _ . 13. The fiber used for RCOM network is _ _ _ _ mode & _ _ _ _index. 14. The Wavelength used for NLD route is _ _ _& for Access route cable is _ _ _ _

48

TOPOLOGY Module 5

49

NETWORK TOPOLOGIES

50

51

Exercise - 3 : Star vs Ring Topology Let’s consider a location with 16 Access nodes, equidistant from a Switch located at the center.

1

16

1. What would be the total distance of media in Star Topology:

2. What would be the total media distance in Ring Topology with two rings as shown: 9 8

1) 16 R = 8D 2)

II D + 2D = 5.14 D

52

Exercise – 4 :

Star vs Ring Topology

In a similar location let’s consider 8 Access nodes with a Switch located at the center. Now:

1

8

1. What would be the total distance of media in Star Topology:

2. What would be the total media distance in Ring Topology with two rings as shown: 4

5

1) Star - 8 R 2) Ring - 3.14 x2R + 4R = 10.28 R

53

Star vs Ring Topology • Total media distance is not necessary more/ less for Star/ Ring topology. • It should be examined on a case to case basis. • In Star- transmission remains point to point between each node. • In Ring topology- Data keeps on adding till it reaches switch / destination Hence needs more Band width.

•In Ring a Add-drop function/ technique is needed at each node.

• In Star - link failure results in - isolation of that node.

•In Ring link failure can be overcome by reverse route and protection technique.

Although a major advantage, the Ring topology doesn’t necessarily reduce the amount of media used in the network. In this example the length of media used in the Star topology is 16r (r= radius of the circle, where the Access nodes are located, the Switch is located at the centre). The length of the two Rings (not necessarily the only solution, you can think of using just one ring as well) work out to 2*( 2r+ πr) ~10r. That is certainly less than 16r used in the Star topology. But if the number of nodes were say 6 or 8 (anything less than 10) the media required in Star would have reduced to 6r or 8r, less than the Ring topology. The planners still prefer to go for the Ring, keep the future needs in mind. The obvious advantage, it seems, is the availability of protection. But this needs examination. In a Star topology if a link fails only one node is cut-off from the network, thereby isolating the problem. In a Ring if a link fails, all the nodes which are beyond this link would get cutoff thereby precipitating the problem. However, if you have the necessary technique you can approach the cut-off nodes from the other side and continue to communicate. As you can see the advantage of protection is only available if you have the suitable technology to provide you the same and not by topology alone. But the ring topology brings in it’s own complexity. The transmission is no more point-to-point as in star. Information from the Switch to a Node x, has to travel to many other nodes before reaching it’s destination. It also means each such set of info actually moves on the ring with several other sets of info. How these information are picked up, added to the collection and than segregated and delivered at the right node is the technology what we will study in this course.

54

THE LEGACY TECHNOLOGY PDH Module - 6 Type in 'MIT Open University' in Google and find a large amount of PDF documents from MIT electrical eng department and from Sloan business School

55

ANALOG - DIGITAL CONVERSION Human Voice ranges from 300 - 3300 Hz, --- - -Maximum 4000 Hz Nyquist Principle.- to be sampled at least at double that rate for recreation So 8000 samples are taken per second for each voice signal.

01110010100011101110

So 8000 samples / second for each voice signal. =1 sample / every 125 micro sec. = 8 bit Data capacity reqd. per individual = 8bits/sec. x 8000 samples = 64,000 bits/sec. = 64 kbps = Data Speed Total data transferred per second = 32 channels x (64,000 bits/sec) Band width = 2,048,000 bits / second = 2.048 Mbps = E1 We need to take atleast 8000 samples to faithfully recreate human voice, meaning one sample takes 125 μs - to transmit. Each sample time duration of 125 microseconds is called FRAME (e.g. train) As we take a 8 bit / sample - we get 64,000 bits/seconds = 64 kbps - to be transmitted per second. A single channel of Voice needs 64 kbps to communicate.- known as Data Speed i.e. in a second–Talking capacity -Data transfer capacity of each individual is 64kbps. This 64 kbps is called a DS0 (Digital Signal Zero). –Data speed of Individual For Video conference we need 60 Mbps.- In Japan each gets 100Mbps,- In USA it is 2Mbps 125 micro sec. FRAME - -can be compared with - - - - - - - TRAIN – 32 channels - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - -BOGGIE – 8 bits = are comparable to - - - - - - - - - - - - - - - - - - - -- -Passengers . Time Division Multiplexing - TDM During 125 micro seconds-Each person’s talk will be sampled for 3.9 micro seconds only. During rest of the time (121.1 microsecond) we can send 31 more signals each of 8 bits. i.e.125 micro seconds is divided into 32 slots / channels & is called TDM i.e. 32 person can talk – one by one - within 125 microseconds i.e. When we bunch 32 DS0 &transmit them at the gap of 125 Microsecond. Each channel is called as Eo. Each frame E1 carries 32 E0 / channels - each channels of 8 bits . Total data transferred per second = 32 x (8bits x 8000 samples/sec.) Band width =2,048,000 bits / second = 2.048 Mbps = E1

56

Digital Signal – Time Division Multiplexing - TDM U1: Framing Alignment

DS0 (64 kbps)

Signal

Time Division Multiplexer

E1 (2.048 Mbps)

U2: Traffic

U4: Traffic

U16: Signaling

32:1 Multiplexer

U3: Traffic

U32: Traffic

8*32 bits/ 125 μs X 8000 (samples/sec.) = 2.048 Mbps Two person can talk on a same fiber at the same time – Multiplexing - may be on diff. Frequency - FDM - May be with diff. Code. (diff. language Gujarati-Hindi-Marathi – English - CDM - May be at diff. Time – i.e. time division Multiplexing – TDM During 125 micro seconds - the person will be talking for 3.9 micro seconds only (Ear to mouth delay is 250 mili seconds) During rest of the time we can send 31 more signals each of 8 bits.i.e.125 micro seconds is divided into 32 slots / channels ( e.g. bogies) & is called TDM i.e. 32 person can talk – one by one - within 125 microseconds Out of 32 channels – 1st i.e 0th channel is reserved for Isolation / Frame Alignment signal (FAS). It Indicates starting of next frame. 16th channel is reserved for SIGNALING ( about starting of call & End of call) Rest of the 30 channel are for Speech or Data (PAY LOAD).e.g. Fruit hawker with Fruits (Payload) in a basket (Overhead) However, as the golden rule of 125 μs remains, when we multiplex 32 channels we get 32*8 bits to be transmitted within the same time. Thus the bandwidth of an E1 signal becomes 32*8*8000/s = 2.048 Mbps and not just 64 kbps. The Multiplexer is a device, which takes one Byte (8 bits) of each of the 32 channels per 125 microsecond, one at a time, and transmits the same. Thus an E1 appear as a bit-stream with 32 words or 256 bits in every 125 μs. While DS0 is the least measurement for “line” (customer connection), E1 is the least / Primary measurement for the “trunk” (network connection). Multiplexing gives one great advantage – you can use one trunk line instead of 32, that saves lot of copper. ERLANG – Max. no. of voice that can be transmitted

57

Analog to Digital Conversion 375 µ Sec 250 125 000

(after each 125 µ Sec)

255 223 191 159 127 95

00010101 01011111 10111111 10110011

1ST VOICE

AT

00010101 01011111 10111111 10110011

00010101 01011111 10111111 10110011

63 31 0 00010101 01011111 10111111 10110011

191 179 95 21

0 Micro seconds

2nd VOICE

AT

125 Micro seconds

3rd VOICE

AT

250 Micro seconds

4th VOICE

AT

375 Micro seconds

Analog :- Continuous discrete signal e.g. mother says child has a fever.( it does not give any idea about temp). Digital : - Scaling the signal, -Quantifing the value.

58

E1 Multiplexer

µ Sec

TS0 TS1 TS2 TS15

TS29 TS16 TS15 TS17 TS30 TS31 TS2 TS29 TS1 TS0 TS15 TS16 TS30 TS1 TS0 TS2TS15 TS17 TS29 TS0 TS1 TS16 TS17 TS2 TS16 TS0 TS15 TS17 TS1 TS2 TS15 TS16 TS0 TS1 TS2TS15 TS0 TS1 TS2

TS0 TS1 TS2

TS0 TS1

TS0

TS16 TS17 TS29 TS30 TS31

For 125 Microsecond frame- Each channel carries 8 bits-i.e. total 32 channels For our networking each DS0 is 64 kbps If 96 channels are to be accommodated then we need 3 E1 But at Access level / Local level –It happens that data speed of 64 kbps-allotted to one customer may be divided among more then one customer by the local network operator to earn more revenue -Ultimately each customer gets the less speed . Data is transferred on the network in the sequence of 36 bytes of 1st TU12 & then that of 2nd TU12 & then that of 3rd TU12

59

Unipolar and Bipolar Signals 0

1

0

1

0

0

1

0 UNIPOLAR SIGNAL

0

1

0

1

0

0

1

0

BIPOLAR SIGNAL Every Time return to Zero (RZ)

While signal as converted from analog to digital in the first place, to reduce noise and attenuation issues, research has shown that there can be several ways of transmitting digital signals itself to make further improvement in reliable transmission. Signals transmitted through electrical wires which are susceptible to Electromagnetic Interference (EMI). Wires behave like antenna and pickup the EMI signals thereby distorting the original signal transmitted through it. There are several methods of minimizing this noise.

1. Unipolar – 0 is shown as 0 & 1 is shown as +1 2. Bipolar – 0 is shown as -1 & 1 is shown as +1,& Between every 2 pulse it touches zero In case of Bipolar signals there are two signal carrying wires, each one is equally susceptible to noise. Thereby the noise pick-up in both the wires cancel each other as the signal is the voltage difference between the two wires. So every time it returns to Zero.- Consumes more power. – Gets heated up. Another issue is that of synchronization, when one node tries to synchronize with respect to the other using the incoming bit stream. A PLL (Phase Local loop ) at the receiver keeps tracking the rising/ falling edges to generate a local clock. However, if the bit stream have continuous 0’s or 1’s, then the PLL losses track. To avoid this happening, signals are continuously returned to zero voltage level.

60

CODING METHODS - Automatic Mark Inversion (AMI) Alternate 1’s are made (+V) and (-V), 0’s are kept as 0.• Only half pulse-width is used to transmit +/-V. • Prevents droop in the line because maximum time spent at +/-V is 1/2 pulse.

+V

time

0

-V

1

1

0

0

1

1

1

1

0

0

1

1

: Transmitted data

Having arrived at the Bi-polar Return to Zero technique, the next obvious effort was to reduce the total number of switching at the transmitter. As number of switching proportionately increases the heat dissipation, it was essential to reduce this for faster transmission. To achieve lesser number of switching a novel coding technique was evolved. Only the 1’s were transmitted as +V/-V and 0’s were transmitted as zero-volt. Thus number of switching was reduced to the number of 1’s transmitted (on average you can expect 50% of bits are 1’s and rest are 0’s, thus switching losses is reduced to half). With AMI therefore alternate 1’s were transmitted as +V and –V, and 0’s are transmitted as 0v. Droop – Drop in Voltage (signal attenuation),if the width of the pulse is more (say 3 number of 1 in a sequence) -in that case after the 3rd 1 , voltage value will be some what less than 1. But in this case voltage is built up for ½ the time of pulse only hence chances of drop in voltage is avoided.

61

CODING METHODS - High Density Bi-polar-Three-zero (HDB3) 1’s & 0’s are transmitted like AMI, until four 0’s are encountered. • But set of four 0’s are substituted by 0’s and B (balance) & V (violation) pulses. • If odd number of 1’s precede four 0’s - transmit three 0’s followed by V-pulse (0 0 0 V) • If even number of 1’s precede four 0’s - transmit B-pulse, two 0’s, V-pulse ( B 0 0 V) •Polarity of B & V-pulses would be depend on the last pulse.

+V 1

B

V

0

Time

1

-V

0

1

V

1

0

0

0

0

1

1

V-pulse

0

0

0

0

0

0

0

0

: Data

B-pulse V-pulse

AMI would bring back the old problem of synchronisation, in case of a long string of 0’s the receiver PLL will lose track.i.e. receiver always looks for change i.e. 0 or 1 but if there are more then 3 consecutive zero-then receiver gets confused - Hence HDB3 To overcome this - a variant of AMI was proposed called HDB3. In this normal 1’s and 0’s are transmitted like AMI.

If after cont. odd number of 1 when 4 0’s are found in a row, the last 0 (I.e. 4th 0 in a row ) is transmitted as 1( Violating Pulse ) on them same side of last 1 pulse. The polarity of this V- pulse would be same as that of the last pulse (corresponding to the last 1) transmitted. .(Generally all 1 will be alternate but in this case , after 3 0 there is 1 but on the same side , There by there would be a violation of AMI code, hence Receiver will identify as V-pulse & will is decoded as a 0 at the receiver. If there are contineous 4 0’s,after contineous even no. of 1 - then both a Violation pulse (for 4th 0) and a Balancing pulse (for 1st 0 in the row of 4 0’s) are transmitted. These B & V pulse are on the same side There by there would be a violation of AMI code, hence Receiver will identify as B Pulse & V-pulse & will is decoded as a 0 at the receiver. If there are 12 Zero – i.e. Zero number of 1 i.e EVEN no of 1 - between 1st set of 4 zero & 2nd set of 4 zero, i.e B00V but with changed polarity & so on i.e +(BOOV) , - (BOOV), +(BO0V) Odd no. os 1 - Even no. of 1

1, 3, 5, 7, – 0, 2, 4, 6,

HDB3 & AMI is done at the transmitter-precisely at tributary card level in ADM. Known as line coding & Encoding 2Mb / 34Mb – HDB3 , = 45 Mb – Bipolar Triple Zero substitution – B3ZS 140 Mb – Coded Mark Inversion (CMI)

62

Scrambling & De-Scrambling – Optic Signal † † † † †

†

Optic Signal has no + / - value. To avoid continuous - more then three 0 or 1 Manchester coding technique is followed i.e. Data is Scrambled at Transmitter . Uniform distribution of 1& 0 – Avoiding continuous - more then three 0 or 1 De- scrambled at Receiver end in the reverse pattern , so as to have the same format as it was before Scrambling.

63

Error Checking – Parity Bit Error Checking • Tools

that enables the RECEIVER to check if error has occurred in transmission.

• Is applied over a collection of transmitted bits called PAYLOAD. • In case of error, the entire Payload is identified to have error, specific error bit is not detected. • Error codes are added on top of payload and hence form part of OVERHEAD.

Parity bit/ flag • One bit flag indicating, the number of 1’s in a payload is odd or even.

• Receiver can check the same upon receiving the payload and detect if any bit has changed. • Parity check would fail if two bits change (0 to 1 or vise-versa) • To minimise the chance of two bit error, parity is applied to small payloads.

Rather than counting number of 1 , can we count number of Zeros? Yes ,but in order to have standardization, As per ITU-T, Everybody has to count number of 1’s to find Bit Error

64

Error Checking – Parity Bit Payload 010100100111010101110010101010100101010100001110101011110101

1+1+1+1+1+1+1+ …………………………….. +1+1+1+1+1+1+1+1+1 = 119

Even parity is set, so Parity Fag (bit) is set to 0 010100100111010101110010101010100101010100001110101011110101

Payload

1

Overhead

• Parity can check for errors, but can’t tell which bit is erred • Parity check fails in case of even number of bit errors. •We ‘ll not come to know which bit is faulty. •Suitable for small loads like 5000 to 10,000 bits Error Checking • Tools that enables the RECEIVER to check if error has occurred in transmission • Is applied over a collection of transmitted bits called PAYLOAD • In case of error, the entire Payload is identified to have error, specific error bit is not detected • Error codes are added on top of payload and hence form part of OVERHEAD Parity bit/ flag • One bit flag indicating, the number of 1’s in a payload is odd or even. • Receiver can check the same upon receiving the payload and detect if any bit has changed • Parity check would fail if two bits change (0 to 1 or vise-versa) • To minimise the chance of two bit error, parity is applied to small payloads.

65

Cyclic Redundancy Code for - PDH Cyclic Redundancy Code (CRC) is generated by mathematical calculation on a block of data so as to return a code which uniquely represents the content & organization of the block. It’s like a fingerprint. Like fingerprint, CRC is used to check the integrity of data transmitted on any medium. The Transmitting party (A) calculates CRC for 8 frames- (adds the CRC with the block of data)-& transmits immediately after those 8 Frames. This CRC is transmitted after each 8 frames. The Receiving party (B) calculates the CRC on the block of data, as received, and cross-checks with the CRC received. If both of them match the data received is taken to be authentic.

These CRC is for PDH only

66

Cyclic Redundancy Code - CRC 1. For Larger load, instead of bits we consider Payload as a collection of bytes: 01010010

B1

01110101 01110010 10101010 01010101 00001110 10101111 01011100

B2

B3

B4

B5

….

Bn-1

Bn

2. Sum total of payload bytes is divided by CRC polynomial

ΣBi = Q, Reminder

x:

x

3. Reminder is transmitted along with the payload: 0101001001110101011100101010101001010101000011101010111101011100 rrrrrrrr B1

B2

B3

B4

B4

….

Bn-1

Bn

4. In case of Error (1 bit or more) reminder value will change, Q may remains the same :

ΣBi + Δ = Q’, R’

x

Cyclic Redundancy Code (CRC) is generated by mathematical calculation on a block of data so as to return a code which uniquely represents the content & organization of the block. It’s like a fingerprint. Like fingerprint, CRC is used to check the integrity of data transmitted on any medium. The Transmitting party (A) calculates and adds the CRC with the block of data, which it transmits. The Receiving party (B) calculates the CRC on the block of data, as received, and cross-checks with the CRC received. If both of them match the data received is taken to be authentic

67

Digital Signal (DSn) Multiplexing (contd.)

Obviously E1 is not good enough, as in urban locations and now even in rural areas, 30-32 DS0’s mean very little. Take a small housing complex in any small city. A 7 storied building with 2 wings, 4 flats per wing per floor would have more than 30 lines. Take 16 such buildings, you would need 16 E1’s. Do we lay 16 trunk lines for 16 E1’s. No we further multiplex. The Multiplexing of 4 E1’s to give an E2 is called Bit Interleaving, where other than the four E1’s, four DS0 signal channels are also added and multiplexing is done bit by bit with stuffing bits added to take care of real time differences. Similarly four E2’s and another 9 DS0 signaling channels are multiplexed to give an E3. Stuffing bits are required as different E1’s coming from different multiplexers are expected to be out of sync by a few bits.

68

Digital Multiplexing - Standards - PDH E5 T4

E4 E3

T3 T2

E2 E1

T1 + 2 = 32

E0

T0

PDH comprises of E1 – E2 – E3 – E4 – E5 - Used by the Customer E3 = 34.368 Mbps say 35 Mbps. For North American standard the 3rd level is known as DS3 = 44.736 Mbps say 45 Mbps. Where as SDH comprises of STM-1 , STM – 4 , STM – 16 ,STM –64 , PDH clock accuracy = +/- 50ppm SDH clock accuracy = 0.00 001 ppm = 0.00001 / 106 =

10-11

Another shortcoming with PDH is that while the same technology is used world-over, manufacturers follow different versions of the same. While the Europeans follow the E1, E2, E3, E4 as we have discussed before, the North American have different set of multiplexed signals: DS1, DS2, DS3, DS4. And as you can see DS2 is not equivalent of E1, neither is DS2 that of E2 or for that purpose not a single NA signal matches with the European signal. This could be a huge concern if any Operator chooses to use equipment of different make, some European, some NA or Japanese.

69

Limitations of the PDH media Bandwidth: BW

Distance: d

Distance

Distance

Bandwidth

BW * d = k

Bandwidth

Electrical Media, like Copper wires, exhibits a BW – distance relationship given by: BW * d = K (constant) The value of constant K will change for different types of Cables, but the relationship is true for all. It is not that the signal gets completely attenuated (that is yet another factor) the effect of high bandwidth is on the shape-factor of the pulses. As the cable act as a low pass filter, the attenuation for higher frequencies are more. Thereby in case of high bandwidth, after the stipulated distance the pulses would lose more of it’s high frequency components and become un-comprehensible. Such pulse are liable to produce higher bit errors than acceptable.

70

PDH – Limited Capacity with Copper E1 E3

E4

Digital Signal Bit Rate (Mbps)

Eqv. DS0

Media

DS0

.064

1

Twisted Pair

E1

2.048

30+2

Twisted Pair

E2

8.448

120+8+4

Twisted Pair

E3

34.368 Mbps

480+32+25

Twisted Pair

E4

139.264

1920+128+100 Optical Fiber

Now consider this: PDH, which was essentially designed to use copper as the media, runs into a roadblock at the higher bandwidths. Electrical cables have this characteristic that the product of bandwidth carried in a cable and the distance to which it can be transmitted reliably is constant.

Band width x distance = Constant Which means if we transmit higher bandwidth, we can do so over a shorter distance only.As the Band width increases, the dist (to which it can be transmitted ) reduces Beyond which we have to regenerate the signal. Now consider this: in practical implementation we require E1’s in the local loop (1-2 km), E3’s in the LE to TAX (5-200 km) and E4’s in TAX to ILD GW (100 – 1000 km). i.e. we use lower bandwidth at short distances and higher bandwidths over long distances. While for an E3, we may use regenerators. For E4 it becomes commercially impractical to use electric media any more. The obvious choice is OFC.

71

Exercise 3: Plesionchronous Slip PDH allows +50 ppm inaccuracy in the timings of the E1 Trans-receivers. Consider a E1 Transmitter transmits frame in 125 μs - Δ and the Receiver receives in 125 μs + Δ ( Δ corresponds to the +50 ppm inaccuracy). Thereby how many bits slip would occur over a period of 1s. Please calculate for yourself: 1. An E1 Trans-receiver transmits/ receives @ 2,048,000 bits per second. 2. Transmitter is transmitting for 50 μs less over 1s (50 ppm of 1s is 50 μs). 3. The Receiver receives for 50 μs more time. 4. Total slip duration is 100 μs. 5. Total slip = 2,048,000 *100 /1000,000 = 204.8 bits

You may have observed that the maximum slip would be about 205 bits over 1s for a E1 line. As 8000 frames are transmitted over 1s, you would not get to see a bit mismatch in every frame. However, over 40 frames (in the extreme case as in this example) 1 bit slip might occur.

72

PDH – Add Drop System - Cumbersome As would be evident from the illustration below, extraction/ addition of individual channel (E1) from/ to a higher level signal (say E4) is very complicated, needing dedicated Multiplexers and Demultiplexers. E3

140

34

E4

140 M

34

140

140 M

E4

E2 34

8 8

34

E1 8

2 8

2

Customer

In legacy Plesionchronous Digital Hierarchy (PDH), while E1’s are multiplexed to give E2, E2’s to give E3 and so on, the method used is that of Bit interleaving. This is done to take care of mismatch in timings of various E1’s. As you can see E1’s coming from various concentrators could have a large tolerance in their timing. Meaning thereby when you receive all the 32 bits of one E1 you may have received only 31 or even 33 bits of another E1. Only way out was to do bit stuffing. The problem is same when we multiplex E2’s or E3’s. So further bit stuffing is applied. In turn we keep losing the identity of individual E1’s. If we consider each E1 as an envelope with 30 lines of message from 30 voice channels, then while we bit interleave and bit stuff, the envelope losses it’s identity and 30 lines of this one E1 gets mixed with 30 others and more lines. In the entire system if an E4 is routed from point A to B and an E1 out of this E4 is to be dropped or added at an intermittent point C, then the entire E4 needs to be demultiplexed to give away one E1 and re-multiplexed to add an E1. This made Ring topology unviable with PDH.

73

Limitation of Plesiochronous Transmission 1. Ideally suited to star topology - Point to point connection - not for Ring network. 2. Clock information derived from Incoming data.No Central Clock. Clock Accuracy +/- 50 ppm

(SDH clock accuracy = 0.000 01 ppm) = 10 -11

3. Dropping or adding E1’s or any trunk in between is cumbersome and costly. 4. Ideal till the medium is Copper – Capacity constraint – 34 Mbps. Limited to sub- Gigabit transmission on copper. 5. Capacity improvement difficult & costly. Not easily scaleable/expandable to higher capacity). 6. In-compatibility between variants (Europe, NA, etc.) Limitation of PDH arises from the bit interleaving which makes extracting or adding a lower order trunk between two points very cumbersome (Equipment for the same are costly). Thus it was ideal for point to point transmission, where all the DS0’s and E1’s are multiplexed at one point (normally at customer locations) and demultiplexed at the switch and vice versa. Similar multiplexing of E1’s and E2’s are done at class 5 switches and carried to a class 4 switch, where they are demultiplexed. Adding further capacity was also difficult requiring addition of large multiplexers, thus increasing demand for bandwidth PDH became less viable. PDH ideal for a star like configuration. Also it was ideal as long as the medium was copper. But as the demand for bandwidth increased it was evident that OFC would be the medium of choice ITU has not approved / standardized OFC as a media for PDH, because commercially not viable. .Also for high Bandwidth Ring configuration would be more viable whereas PDH is Ideally suited to star topology -not for Ring network. Finally PDH was limited to sub-Gigi bit per second transmission making it unrealistic for modern day needs. Thus a new standard was born. PDH clock accuracy = +/- 50ppm SDH clock accuracy = 10-11 i.e.= 0.00 001 ppm

Why to Use PDH ? PDH technology is old & past dated but we can not ignore ,because still we use certain equipment at Access / BTS – operating at Lower range – based on PDH Technology & Need has not arised to go at higher range (SDH) at this level. Hence continued.

74

Module Review - Exercises - 5 1.

Sampling frequency rate for human voice is ………………… samples/ second.

2.

E1 comprises …….. DS0’s and E2 comprises ……. E1 + …….. DS0’s

3.

In SDH E1 trans-receivers are allowed to have clocks with ……….. ppm inaccuracy

4.

In PDH E1 trans-receivers are allowed to have clocks with ……….. ppm inaccuracy

5.

E1, E2, E3 are ………....…. variant of PDH and T1, T2, T3 are ……....…. variant

6.

Media recommended for E1 to E3 is ……………., while it is ……………. for E4

7. 8.

PDH is ideal for ………….. to ………… transmission and …………… topology. How many bits / channel / 125 micro sec. _ _ _ _ _ _ _ _

9.

What is channel (DS0) bit rate (data speed). _ _ _ __ _ _ _ _ _

10.

What is time duration of each Frame _ _ _ _ _ _ _ _ _ _

11.

How many channels (slots) / Frame

12.

Number of bits per Frame _ __ _ _ _ _ __ _ __ __ _ _ __ _

13.

Process of dividing Frame in to 32 channels is known as _ _ _ _ _ _ _

14.

What is the Band width (bit rate) of E1 . __ _ _ _ _ _ __ _ __ _

_ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _

75

SYNCHRONOUS DIGITAL HEIRARCHY

(S D H)

Module - 7

76

Synchronous North American

Digital European

SONET

Optical

SDH

Hierarchy Line Rate (Mbps)

Signal Designation

(OFC)

OC-1

STS-1

STM-0

51,84

`

OC-3

STS-3

STM-1

155.52

OC-12

STS-12

STM-4

622.08

OC-48

STS-48

STM-16

2,488.32

2 Gbps

OC-192

STS-192

STM-64

9,953.28

10 Gbps

OC-768

STS-768

STM-256

39,813.12

STM = Synchronous Transport Module STS = Synchronous Transport Schedule SONET = Synchronous Optical Network OC = Optical Carrier = Interphase

European std.s Synchronous Digital Hierarchy (SDH) and it’s North American counterpart SONET proposes a transport system with highly synchronised network elements and OFC as the physical media. Thereby the concept of bit-interleaving is replaced by a Byte interleaved system. Also the bandwidths are defined upto much higher range making it suitable for modern data & broadband communication. SDH/ SONET defines to types of “packaging” – one for the electrical network called Synchronous Transmission Module/ Schedule (STM-n/ STS-n) and another for the optical network called Transport Unit (TU-n)/ Optical Carrier (OC-n). STM-n has now been defined from STM-1 (63 E1’s) to STM-64 (4032 E1’s). Proposal for STM-256 is under examination for standardising. That would take us to an amazing 40 Gbps. Technically there are small differences between SDH and SONET. Some terms differ and some details in Overhead definitions differ but that doesn’t come in the way of making these to standards compatible to each other. Technically there is no difference between SDH and SONET. Some terms differ and some details in Overhead definitions defer but that doesn’t come in the way of making these to standards compatible to each other.

Traffic intensity can be Access – User to Access point i.e. BTS -

STM - 1 to STM – 4

MA / BA ring – BTS to Switch

STM - 1 to STM – 16

-

Core / NLD / NBB - Switch to switch -

STM - 1 to STM – 64 77

SDH Multiplexing Structure

C12

+1 POH VC12

+1 Pointer TU12

34

35

36

C11

+1 POH VC11

+1 Pointer TU11

25

26

27

+2 E1 32 Bytes

+1 T1 24 Bytes

36X3 TUG2 108 27X4 108

T2

C2

POH

Pointer

VC2

TU2

VC12 - European standard – 2 Mbps VC3 VC4 -

- 34 Mbps - 140 Mbps

TUG2

Legend C - Container VC - Virtual Container – SDH Mapping TU - Tributary Unit - Aligning TUG - Tributary Unit Group AU - Administrative Unit AUG - AU Group STM - Synchronous Transport Module E1 - has 30 Bytes known as Pay Load for which customer pays & the company earn the revenue for the same

VC11 - N. American standard -1.5 Mbps VC 2 - N . American – 6 Mbps VC 3 - 45 Mbps

Before we look at the big and the jumbo boxes, lets see how your small E1 is packed in a TU12. Stuffing / Justification : 32 Eo makes E1. The 32 bytes of an E1 (in a time frame of 125 μs) is called the Payload. In PDH data of each E1 is varying in speed / size. Therefore may or may not provide exactly 32 bytes within 125 micro second slot. We may receive slightly more or less bytes i.e.E1 = 2.048Mbps +/- 50 ppm = 2,048,000bps+/-100bits . Now if we want to pack it in a container (C12) , The size of a container should be some what bigger to accommodate this variation. Hence the the container C12 is so selected that it can accommodate additional 2 bytes i.e. total 34 Bytes.i.e. when E1 is packed in a container 2 Bytes are added to it (Cushioning) & is known as C12 (A Synchronous container) These 2 bytes are known as Justification / stuffing Bytes .It may contain Data, It may not contain data ,it can be dummy / redundant. These take care of any disparity in the Real Time Clock of the E1 sources and the SDH equipment. Whenever it is + , Additional 2 bytes can accommodate it ,But when LESS ,We need some packing i.e. these two will be used as dummy bites to maintain the packet size . – It is shown as S1 & S2 & is indicated by C1-C2. If E1> 2.048Mbps then S1/ S2 will be Data .Then C1/C2 =1 If E1< 2.048Mbps then S1/ S2 will be Packing .Then C1/C2 = 0 From the value of C1&C2 , Receiver will come to know whether S1,S2 is to be retained or to be thrown out. Then we add One byte which carry the Path Overhead. POH carry the information about sender and destination addresses-along with other details. These details are added at starting point (Transmitter end) & checked at Receiver end. Now it is known as VC12 Then we add One byte which carry the Pointer & is known as Tributary 12-TU12 TU 12 = 32 (E1) +2 stuffing +1 Path over head + 1 Pointer =36 Bytes & time permitted is 125 Micro sec .

78

Virtual Container (VC12) – Multiframe & POH K4 R

VC-12 Path Overhead

R

R

R

R

R

R

R

R

R

J2 R

R

R

R

R

R

R

R

V5 R

R

R

R

R

R

32 Bytes Payload (256 bits) R

R

R

R

R

R

R

R

R

R

N2

R

R

R

R

R

R

R

R

R

32 Bytes Payload (256 bits) R R

R

R

R

R R

32 Bytes Payload (256 bits) R

R

R

R

R

R

R

32 Bytes Payload (256 bits) R

R

R

R

R

R

R

Stuffing Bits

Before we look at the big and the jumbo boxes, lets see how your small E1 is packed in a VC-12. The 32 bytes of an E1 (in a time frame of 125 μs) is called the Payload. They are safely cushioned by two bytes of Stuffing bits. These take care of any disparity in the Real Time Clock of the E1 sources and the SDH equipment. Then we add a byte which carry the Path Overhead. POH amongst other things carry the source and destination addresses. This is your small box, ready to be shipped, time allowed 125 μs. The next 32 bytes of the next 125 μs gets similarly packed and thus the process goes on. Only observe that the POH of the four boxes in four consecutive time slots are named as V5, J2, N2 and K4. Why – see next slide. VC-12 Multi frame - It is combination of 4 E1 frame, each of 125 Micro sec .i.e. A Multi frame takes 500 micro sec. for transmitting. PAY LOAD – Customer is paying for – e.g. Fruits in the basket of a fruit seller OVERHEADS – required for managing the system – no revenue earned – e.g. basket of a fruit seller. V5, J2, N2 and K4 together carry 4 byte (1- POH Byte of each frame) . 4 such VC-12’s form a VC-12 Multi frame. A Multi frame takes 0.5 micro second for transmitting. Path Over Head: A Circuit joining joining two Main station (node) that passes through number of intermediate nodes. The extra information related with the path is generated at originating point – remains throughout-& processed at Terminating Point is called as Path Over Head In SDH some capacity is reserved for carring / monitoring &Management information related with the path.This extra information like where it come from & where it should go is called POH (Path over head) It allows checking of a) The quality of overall end to end transmission. b)The existance of a path between two terminating points. c) It allows remote end (Receiver) to communicate to the transmitter end that there is trouble with the signal received. When received by Receiver it gives a complete POH with Starting point & End point address along with other other information.

79

VC-12 Multiframe &

V5 RRRRRRRR

VC-12 Path Overhead

32 BYTE PAYLOAD FRAME 1

V5 R

R

R

R

R

R

R

R

R

R

R

R

R

125 μs Provision for Justification bits is kept to take care of 2 Mbps + 50PPM frames

RRRRRRRR J2 C1 C2 OOOO RR 32 BYTE PAYLOAD FRAME 2

32 Bytes Payload (256 bits) R

Path Overhead

RRRRRRRR N2 C1 C2 OOOO RR

R

R

Stuffing Bits

500 μs

32 BYTE PAYLOAD FRAME 3 RRRRRRRR K4 C1 C2 OOOO RS1 S2

Justification Bits

31 7/8 BYTE PAYLOAD FRAME 4 RRRRRRRR

V5, J2, N2 and K4 together carry a 4 byte meaningful POH so one VC-12 is incomplete in itself. 4 such VC-12’s form a VC-12 Multiframe. A Multiframe takes 0.5 ms to be transmitted. When received it gives a complete POH with source & destination address amongst other information.

VC-12 Multi frame - It is combination of 4 E1 frame, each of 125 Micro sec .i.e. A Multi frame takes 500 micro sec. for transmitting. V5, J2, N2 and K4 together carry 4 byte (1- POH Byte of each frame) . 4 such VC-12’s form a VC-12 Multi frame. A Multi frame takes 0.5 micro second for transmitting.

80

LOWER ORDER PATH OVERHEAD

BIP: Bit Interleaved Parity

to check parity at the remote end

REI: Remote Error Indication

to indicate parity error from remote end

RDI: Remote Defect Indication to indicate other failures from remote end RFI: Remote Failure Indication to indicate loss of signal from remote end Signal Label: Type of payload to indicate type of payload to remote end

V5 contains the following information: 1&2 BIP2 2 bits Bit Interleaved Parity Error monitoring 1st indicates whether the sum of all odd bits is Even (or Odd as per standard) 2nd indicates whether the sum of all Even bits is Even . 3 - REI 1 bit Remote Error Indication Indicate BIP error If the bits received are Odd, It is Error then Receiver will transmit REI (1 ) to transmitter If the bits received are EVEN –ok-then Receiver will transmit REI as 0 to transmitter. NNOC will come to know about REI through Network Mgt. System (NMS)

4 - RFI

1 bit Remote Failure Indication. If the Error continues for more than Pre set time , Then receiver end will transmits Remote Failure Indication ( RFI )- value 1 - to transmitter end.-Not used at Reliance

5-6-7 Signal Label

3 bits Indicates type of Pay load Unequipped / no load / Tributary not connected, Equipped-non specific , ATM (Asynchronous transfer mode) ,Bit Synchronous, ,Byte Synchronous , Test signal , Asynchronous (at R COM) indicated by 010 ( refer pg no. 86 to 91 of ITU-T G707/Y.1322 for more details)

8 RDI – 1 bit - Remote Defect Indication – Indicates error other then Parity Error e.g. Signal level mismatch or Path label mismatch

81

Type in 'MIT Open University' in Google and find a large amount of PDF documents from MIT electrical eng department and from Sloan business School 000-Unequipped, 001-Equipped-non specific,010-Asynchronous 011 – Bit Synchronous,100 – Byte Synchronous

82

Lower Order Path Overhead: J2 1st Byte: CRC - Cyclic Redundancy Check applicable to 32 bytes *4 *16 = 2048 bytes

2nd – 16th Byte: Path Trace – predefined string attached by transmitter and checked by receiver CRC

N.

M

U

M

B

A

I

-

G

U

R

Mum_A21_s4_1

U

G

A

O

Pune_A07_s11_12

J2= Receiver can verify it’s connection to the Transmitter Each J2 is for Path Tracing Indication (Path Over head) It is having 16 bytes (Character) i.e one byte per 0ne multi frame i.e Each J2 is valid for following 16 multi frames = 16 x (125 microseconds x 4frames ) = 8000micro seconds = 8 mili seconds data . J2 is used for lower order Path Trace. Each J2 is described in 16 Characters 1st J2 byte carry CRC value for path details described in remaining 15 characters. Rest 15 bytes carries path details of starting point to End point. Transmitter will insert / send J2 . & receiver ( Path End point / Terminating ADM ) will Check / Process /start reading it after CRC e.g.If there is no change in path trace

83

Lower Order Path Overhead: N2

Network Network 11 (Operator (OperatorA) A)

Network Network 22 (Operator (OperatorB) B)

N2: Tandem Connection N2 Bytes carry Error & Performance parameters which can be used for quality assurance when two different networks are connected to each other through a POI.

N2 is used to monitor Tandem connections. When two network Operators (e.g.BSNL & RIC) connects their networks, they would like to know the quality of signal they are exchanging. N2 offers such facilities. e.g. If we are sending Mangoes to Dubai side ,we have to mention the suitable temp. say 24 to 26 degree temp. otherwise it will get spoiled. Similarly when we are importing electronic equipment from USA ,they will mention the Power supply details because their equipment operates at 120 volt. It will get damaged if we operate here at 230 volts. K4 - was reserved for future use in 1998 but after 2003 started using it for Automatic protection Switching. - APS Automatic Path Switching will occur within 50 mili seconds. .( it can be 40 ms also or 45 ms also)

84

SYNCHRONISING VC-12 WITH TU12 Pointer (V3)

Pointer (V2)

VC12

Pointer (V1)

VC12

VC12

125 μs

125 μs

125 μs

VC12

Offset

Synchronous Frame

Plesiochronous Frame VC Size

V1

V2

NNNNXX I D

I D I D I D I D 10 bit Pointer

85

Synchronizing VC-12 with TU12 - POINTER Pointer (V3)

Pointer (V2)

VC12

Pointer (V1)

VC12

VC12 125 μs

125 μs

VC12 125 μs

Synchronous Frame Plesiochronous Frame

Offset

VC Size

V1 NNNN

XX

ID

V2 I D I D I D I D 10 bit Pointer

TU12 has 1 Byte as a Pointer . It identifies starting point of VC12 w.r.t. Frame It gives details about Off set & becomes Tributory. Multi frame is a combination of such 4 frames. Hence it has 4 Bytes as Pointer & is known as V1 , V2, V3, & V4. V1 & V2 act as Pointer = 16 Bytes, V3 = Pointer Justification , V4 = not used. 1st 4 Bites of V1 is used for indicating the status of Pointer-Known as NDF i.e. New Data Flag. 1st 4 Bytes of V1 is used for indicating the status of Pointer. a) If it is a new / Fresh Payload Then valued as 1001 B) If is a conitinuation of old Payload - Then valued as 0110 Pointer value can be changed only after 40 frames .The old pointer continues till it is changed. 5th & 6th bytes i.e. 2 Bytes - indicates type of Load i.e. Standard European - TU 12 - Value 10 - Used at Reliance Rest of the 10 Bytes will indicate (In Binary Form) position of Starting Point of of VC12 ( Path lable J2 ) from pointer. when two network (1st network shown by blue colors & 2nd shown by black lines ) is exchanging data - Due to inaccuracy of clock ,It can happen, that First frame of of black network (shown by black lines) may receive only 15 bytes of previous frame & 20 bytes of present frame –the same thing can happen for 2nd frame ,it will receive 15 bytes of present frame & 20 bytes of next frame. i.e each frame is lagging by 15 bytes in 2nd (black) networkIn other words New frame starts after 15 bytes from the staring point of the frame i.e.15 is a pointer value. Pointer is issued by PLM-When Tributory card handover VC12 to PLM, at that time PLM decides Pointer value.

86

Synchronizing

VC – 12 with TU12 Synchronous Frames

K4 34 BYTE

125 μs

V5

V3 V5

34 BYTE 34 BYTES J2

500 μs

V4 J2

34 BYTE

VC12’s N2

TU12’s

34 BYTES V1 N2

34 BYTE 34 BYTE

Position of a VC12’s within TU12’s is known only after receiving POINTER

V2 K4 34 BYTE

Plesiochronous Frames

To understand Pointer – e.g. where you have two watches in your house – one a perfect clock and another one which keep getting fast or slow. Once in a while you match these with a time signal (lets say from NTP or GPS). The first one keep perfect time, so if you tally it’s time after a few days with the time signal again, you would see no difference. But the second one keeps drifting back or forward (depends on whether it is slow or fast). Now instead of trying to resetting the 2nd watch every now and then, you normally keep in your memory a time diff. which tells you how fast/ slow is this second watch. The same thing -happens with the SDH equipment, which have a perfect clock (1st) – aligned with some Primary Reference Clock, because the payload they receive , are from PDH equipment, which are allowed their own clock (2nd - inaccuracies). To take care of this SDH forms - a synchronous frame (Tributary Unit) and allows the Virtual Container to “float” freely in this frame. To keep a reference the VC is pointed by a POINTER, which is put inside the TU along with the VC. In case of TU-12, one byte (name V1, V2, V3 in successive frames) is added on top of the 35 Bytes of VC-12. However, V1 and V2 jointly provides a 16 bit pointer, which as a standard is used for all VC’s upto VC-3 (AU-3). Each count of the Pointer means an offset of 1byte (in case of Higher order Pointer ( H1-H2-H3-H4) of AU-4, Each count of the Pointer means an offset of 3 byte – as shown on page no 91Pay Load Pointer

87

Lower Order Path Over Head Summary Details

LO-POH -

1

Bip Error

V5 1&2nd

2

REI

V5 – 3rd

3

RFI

V5 – 4th

4

Signal Label -

V5 – 5-6-7

000-Unequipped, 001-Equipped-non specific, 010-Asynchronous 011 – Bit Synchronous,100 – Byte Synchronous, 110 – Test Signals 111 – AIS =All ones=Alarm Indicating Signal

5

RDI-

V5 – 8th

LOS, TIM,LOP

6

Path Trace -

J2

7

Tandem Connection

N2

8

APS

K4

9

POINTER

V1,V2

88

SDH

Multiplexing +2

E1 32 Bytes

C12 34

+1 POH VC12 35

Structure – STM 1 (contains 1 E3)

+1 Pointer

36X3

TU12 36

TUG21

108X7

108 T2

C2

POH VC2

C3

T3/E3

TUG3 TUG3 TUG3 E4

774X3=2322 +18 +9 POH

VC4 2340

+9 Pointer AU4 2358

TUG3 774

756

7

Pointer TU2

+18 Stuffing

+9 POH VC3

+3+6 Pointer TU3

+72 SOH AUG1

STM1 2430 Bytes

C4

Bit rate of STM 1 = 2430 Bytes X 8 X 8000 samples/sec. = 1,55.52,000 bps = 155.52 Mbps

Legend C VC TU TUG AU AUG STM -

Container Virtual Container Tributary Unit Tributary Unit Group Administrative Unit AU Group Synchronous Transport Module

When pointer is added to VC4 - it becomes AU4 When AU4 is kept in a container, it is known as AUG1 If AU4 has STM-1 only then AU-4 & AUG1 is the same but If n AU4 are combined & put in a box then it becomes AUG n

Section Over Head will speak about entire STM Load e.g. comparison with Train Transport – (1) When the train had left starting point (2) If there is a path failure –Which are the alternate route available? APS e.g. For a train from CST to Pune – if de-railment occurs at Ghatkoper – Alternate routing Thane will decide for Alternate path - i.e to divert the train from Kurla on Harbour line. - Kurla –Vashi – Thana route. (3) J0 – Path Trace details- For Mumbai to Delhi Train – At Junction station - to see that it is properly diverted for desired destination. e.g. - at Surat to see that train is not diverted to Bhushaval Route - at Ahmadabad to see that train is not diverted to Gandhidham Route At other stations like Vulsad/Bharuch / Vadodara (like regenerators)-we need not check path trace as there is no branching. (4) Quality level of service - Express train like Shatabdi / Rajdhani Express / local train – Stoppage at which stations?. - Where Stock of mineral water bottles to be checked ! - Whether all the facilities are working O.K. – e.g.Fan - At junction station (like multiplexure) –To check for the availabilty of water at Bathrooms & wash basins – to fill the tanks if necessary.

89

STM-1 Payload Structure SDH Multiplexing Structure – STM 1 VC4 3 TUG3

Or 1

TU3

7 TUG2

Or 1

TU2

1

1

VC3

VC2

1

1

C3

C2

1

1

T3

T2

3 TU12 4

1

VC12

C12

VC11

1 1

1

1 TU11

1

C11

E1 T1

90

The STM-1 Coach - VC - 4 - JKLM Labeling Imagine the STM-1 as a coach as shown below:

K=3

VC 3 / E3 / Tug 3

VC 3 / E3 / Tug 3

E1

L=2 VC-2 L= 3 VC-2 L= 4 VC-2

TUG-2 Over Head

M=3

M=2

O

L= 7 VC-2

M=1

M=3

M=2

M=1

2 3

M=1

L= 5 VC-2 L= 6 VC-2 1

Over Head – 29 Mbps

L=1 VC-2

M=3

TUG-2

E1 E1

VC 3/E3/Tug 3

Pay Load = 126 Mbps

K=2

M=2

K=1

O O

91

STM 1 - Transfer module – J K L M numbering Pay Load = 126 Mbps

Pay Load

K=1

21

L= 1 (TUG-2) L= 2 (TUG-2)

Over Heads = 29 Mbps

L= 3 (TUG-2)

E3 VC 3

O

L= 4 (TUG-2) L= 5 (TUG-2) L= 6 (TUG-2)

M=1 M=2 M=3

L=7 (TUG-2)

E1-1

E1-2

O O

E1-3

63 E1 =21 Tug-2 = 21 VC 2/E2 = 3Tug-3 =3VC3/E3 = 126 Mbps STM 1 = 63 E1 + Over heads = 126 Mbps + 29 Mbps = 155 Mbps STM – 1 = E4 = 3 E3 E3 = 7 E2 E2 = 3 E3 STM – 1 = E4 = 3 E3 = 21 E2 = 63 E1 E4 is identified as E3 is identified as E2 is identified as E1 is identified as

J k L M-

can vary from can vary from can vary from can vary from

1 to 64 1 to 3 1 to 7 1 to 3

STM – 1 = E4 + 29 Mbps Overheads = 63 E1 + 29 Mbps Overheads = 2x63 Mbps + 29 Mbps Overheads = 155 Mbps If KLM number is 373 i.e, 3rd E3 – 7th E2 - 3rd E1 - shown by Red J1 K321 & J 1 k300 can not go together An STM-1 can be equated with a container carrier, which can carry various combinations of containers. It can carry 3 TU-3, or 2 TU-3 and 7 TU-2, or 63 TU-12, etc. The drivers cabin comprise of Path Overhead, a Pointer, Regenerator Section OH and Multiplexer Section OH. As we go up the ladder the container section just get bigger and bigger, the driver cabin remains the same.

92

Pack a STM - 1 - Exercise - 6 Given a STM-1 work out the combinations of E3 and E1’s which you can pack in it: 1.

0*E3 + ….…….. E1

2.

1*E3 + ………… E1

3.

2*E3 + ………… E1

4.

3*E3 + ………… E1

5.

………… E3 + 43*E1

6.

………… E3 + 24*E1

7.

………… E3 + 3*E1

8.

On the same Multiplexer section of STM-4 ring –along with J1K321 Can we carry? - J1K300. J2K321,J1K322,J1K373,J1k320,J1K330, J2K300

9.

Which load we can carry On the same Multiplexer section of STM 4 ring _ _ _ _ 12 4 , 321, 3 83, 411,

Different Container/packets for diff. load VC12 = E1 VC2 = E2 VC3 = E3 Vc4 = E4 = 63E1

93

Add – Drop – Through -Configuring Circuits Add-drop

Add – Drop:

E1 = J1 K111 E3 = J1 K200

Add-drop is a Tributary port – Aggregate port association.

E1 = J1 K112

Through: Through is a Aggregate port – Aggregate port association. A -Drop

4*VC-4

E1 = J1 K111 Add-D E1 = J1 K311 Thru’

add-Drop

E1 = J1 K112

E1 = J1 K112 E1 = J1 K311

E3 = J1 K200

4*VC-4

E3 = J2 K100

Add-drop E3 = J2 K100

Thru’

add-Drop

E1 = J1 K112

E3 = J1 K200

E1 = J1 K311

A circuit is configured by allocating the Payload a VC (KLM number) and making Add-drop or Trough connections at relevant ADM’s. At both the terminating ADM’s, Add-drop connection is made by associating the VC to a relevant Tributary port and Aggregate port. Through connection is made by associating the VC to two Aggregate ports (of EastWest modules).

94

SDH STM-1 FRAME - with 2430 serial bytes

9 BYTES

270 BYTES

1 271 541 811

270 540 810 1080

2430

Data is transferred to the network in the sequence shown above i.e. 270 byte of 1st raw first & then 270 byte of 2nd raw & then 270 byte of 3rd raw & so on .

95

SDH - STM-1 Frame Structure 261 BYTES

REGENERATOR SECTION OVERHEAD

AU4 POINTER MULTIPLEXER SECTION OVERHEAD

PATH OVERHEAD

9 BYTES

9 BYTES

OFFSET J1 B3 C2 G1 F2 H4 F3 K3 N1

VC4 = 9 x 260 bytes + 9 (POH)=2349 2340 +9 = 2349

.A STM-1 frame structure Total Number of Columns is 270 i.e. 270 x 9 = 2430 Bytes First 9 columns for RSOH – MSOH –& Pointer Section Over Head = 72 Bytes = RSOH (27 Bytes) + MSOH (45 Bytes) Regenerator Section Over Head = RSOH – 1st 3 Rows = 27 Bytes Multiplexor Section Over Head = MSOH – 5th to 9th Row = 45 Bytes These OH’s carry various section related information for Network Management, Synchronisation, Fault management, etc. Pointer – 4th Row = 9 Bytes

Higher Order Path Over Head – 1 column = 9 bytes Pay load – 260 columns i.e. 260 x 9 = 2340 Bytes

96

SDH STM-1 FRAME STRUCTURE STM-1 Frame Structure - Higher Order Path Over Head VC-4 POH

261 BYTES

REGENERATOR SECTION OVERHEAD

AU4 POINTER MULTIPLEXER SECTION OVERHEAD

PATH OVERHEAD

9 BYTES

9 BYTES

SDH PAYLOAD VC4

The following sections of the presentation explain the Payload, Path & Section Overheads

The Higher Order Path Over Head comprises the following bytes: J1: Path Trace Used to transmit a Path details- like starting point & End Points-so that END POINT (Receiver) can varify .It indicates path across the diff. nodes & final destination. J1( like J2 in LPOH) is used for carrying CRC and Path Trace (string of 15 user-defined characters).-VC4 Path Trace B3: Path BIP-8: B2 carries 8-bits of Parity. BIP of previous frames for Error monitoring In the whole A4-Value of each 8th bit is sumed up –CRC (add.)is calculated & is transmitted with J1 1st Block – Sum of value of 1st,9th,17th bits

& so on

sum of all bits as shown above should be Even (or Odd as per standard) If not Even –transmits 1,If Even Tranmits o 2nd block – Sum of value of 2nd,10th,18th bits & so on 3rd block – Sum of value of 3rd , 11th, 19th bits & so on C2: Signal Label

Indicates composition of the payload

Unequipped / no load / Tributary not connected,

Equipped-non specific ,

ATM (Asynchronous transfer mode) ,Bit Synchronous, ,Byte Synchronous , Test signal , Asynchronous refer pg no. 86 to 91 of ITU-T G707/Y.1322 for more details)

(

97

Higher Order Path Over Head - For VC4 – 9 Bytes J1

Path Trace

B3

Bit Interval Parity BIP- 8

C2

Signal Label

G1

REI , RFI , RDI - Error report

4

F2

User Channel - Equipment Vendor’s use

5

H4

Multi frame Indicator - frame number

F3

User Channel- Path Elements-Service Provider-Maint.

K3

Automatic Protection Switching - A P S

N1

Tandem Connection

1

2

3

6

7 8 9

G1: Path Status - Path terminating status & Performance information.i.e. Error report – REI, RFI - First four bits & RDI - 5th - 6th & 7th bits F2: Path User Channel

Communication between path elements / nodes – For Equipment Vendor’s use H4: Multi frame Indicator This bytes provides a Multi frame & sequence indicator and a generalised position for Payloads. F3: Path User Channel - Communication between path elements -Service Provider uses it for maintenance. K3: – For Auto Protection Switching - APS for APS signaling for protection at VC4 path level. First 4 bits of K3 are used for APS -and rest are reserved for future use. ( APS occurs within 50 mili seconds) N1: Network Operator Byte-Inter operator – inter Carrier – Reliance & BSNL It is used to monitor Tandem connections. When two network Operators (e.g.BSNL & RIC) connects their networks / exchanges their data – say at POI,they would like to know the quality of signal they are exchanging. N2 offers such facilities. ,(like N2 in Lower Order Path Over head – LPOH )

98

Higher Order Path Over Head - Summary Details

H-POH – 9 Bytes

1

Bip Error

B3

2

REI / RFI

G1 – 1st Four bitts

4

Signal Label -

C2

5

RDI-

G1 - 5th-6th & 7th bits

6

Path Trace -

J1

7

Tandem Connection

N1

8

APS

K3 – 1st Four Bytes

9

POINTER

H1 , H2

10

Equipment Vendor, lucent,Nortel

F2

11

Multi frame no.

H4

12

Sevice Provider Maint.

F3

13

Frame Alignment - LOF

14

Engg. Order Wire

15

Data comm

16

Sync. Status

Path Trace

Remaining 4 Bytes are reserved for future use

99

AU - 3 POINTER

It identifies starting point of Payload -Position of J1 - w.r.t. Frame-From the pointer. The pointer is placed by PLM when it collects the data from several tributary & loads it in a Aggregate frame. Pointer will indicate data VC4 starts from which byte behind that Pointer AU4 pointer- 9 Bytes - but 2 are used i.e.H1 &H2 as shown above. H1 & H2 act as Pointer = 16 Bytes, 1st 4 Bites of H1 is used for indicating the New Data - Known as NDF i.e. New Data Flaga) If it is a new / Fresh Payload Then valued as 1001 b) If is a continuation of old Payload - Then valued as 0110 Pointer value can be changed only after 40 frames .The old pointer continues till it is changed. 5th & 6th bytes i.e. 2 Bytes - indicates type of Load - i.e. Standard adopted European - Value 10 - Used at Reliance. Rest of the 10 Bytes will indicate (In Binary Form) Starting Point of of VC4 ( Pay load ) from the pointer. H3 is used for +/- justification. VC4 can be found only if we know Pointer-may be with / without +/- justification. Hence justification is required at this stage. H4 is used as a counter for extraction of V1,V2, V3,----Pointer always jumps in multiple of 3 because maxm. Value it can have is 783 only Pointer is issued by Aggregate Card - When PLM card handover VC4 to Ag. Card, at that time Aggregate card decides Pointer value.

100

PAYLOAD

POINTER 270

99

1 2 34567 89 1 2 Displacement

3 4 H1 y

y H2 1

1 H3 H3 H3

5 6 7 Floating VC 4

8 9 Path Overhead

0

1

1

0

0

0

0

0

0

0

0

H1

1

1

1

1

0

H2 Pointer = 1/3 (270-9)+1/3 (99-9) = 117

0 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 H1

H1

H1

H1

H1

H1

H1

N N N N S S I

H1

H2

D I

H2

H2

D I

H2

H2

D I

H2

H2

D I

H2

D

VC4 is combination of 3 TUG-3,Henc e pointer always moves in steps of 3 Pointer always moves in steps of 3 .i.e. (2430 – 81) / 3 = 783 Maximum value that a pointer can have is 783 Justification also in steps of +/- 3 Bytes Each count of the Pointer means an offset of 3 byte (in case of AU-4),

101

PAYLOAD

POINTER 270

99

1 2 34567 89 1 2 Displacement

3 4 H1 y

y H2 1

1 H3 H3 H3

5 6 7 Floating VC 4

8 9 Path Overhead

0

1

1

0

0

0

0

0

0

0

0

H1

1

1

1

1

0

H2 Pointer = 1/3 (270-9)+1/3 (99-9) = 117

0 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 H1

H1

H1

H1

H1

H1

H1

N N N N S S I

H1

H2

D I

H2

H2

D I

H2

H2

D I

H2

H2

D I

H2

D

VC4 is combination of 3 TUG-3,Henc e pointer always moves in steps of 3 Pointer always moves in steps of 3 .i.e. (2430 – 81) / 3 = 783 Maximum value that a pointer can have is 783 Justification also in steps of +/- 3 Bytes Each count of the Pointer means an offset of 3 byte (in case of AU-4),

102

Management Path - AD End to end connection

A

Multiplexers - A – B - C - D Multiplexer Section (MS)

Regen - X

A section of the path between two ADM’s

AB , BC , CD

Hierarchy

Regen - Y

D

B

Regenerators X – Y - Z Regenerator Section (RS) A section of the path between two Regenerators or between a Regen and a ADM

Z – Regen

AX , XY , YB , CZ , ZD

C

A circuit is configured by allocating the Payload a VC (KLM number) and making Add-drop or Trough connections at relevant ADM’s. At both the terminating ADM’s, Add-drop connection is made by associating the VC to a relevant Tributary port and Aggregate port. Through connection is made by associating the VC to two Aggregate ports (of East-West modules). AD – Short path , ABCD – Long Path

Section Over Head will speak about entire STM Load e.g. comparison with Train Transport – (1) When the train had left starting point (2) If there is a path failure –Which are the alternate route available? APS e.g. For a train from CST to Pune – if de-railment occurs at Ghatkoper – Alternate routing Thane will decide for Alternate path - i.e to divert the train from Kurla on Harbour line. - Kurla –Vashi – Thana route. (3) J0 – Path Trace detailse.g. For Mumbai to Delhi Train – At Junction station - to see that it is properly diverted for desired destination. e.g. - at Surat to see that train is not diverted to Bhushaval Route - at Ahmadabad to see that train is not diverted to Gandhidham Route At other stations like Vulsad/Bharuch / Vadodara (like regenerators)-we need not check path trace as there is no branching. (4) Quality level of service: - e.g. in case of Express train like Shatabdi / Rajdhani Express / local train – Stoppage at which stations?. - Where Stock of mineral water bottles to be checked ! - Whether all the facilities are working O.K. – e.g.Fan - At junction station (like multiplexure) –To check for the availabilty of water for Bathrooms & wash basins – to fill the tanks if necessary.

103

Management Hierarchy Path –Mumbai to Jaipur Multiplexer Section (MS) Ahmadabad to Jaipur M-2 - M-3 Mumbai – Surat M1 – M2 Mumbai to Jaipur – M1 to M3

Regenerator Section (RS)

C M-3

Jaipur

Ahmadabad

M-2

Mumbai to Surat - M1 - G Surat to Ahmadabad G - M2

G

SURAT Mumbai

M-1

E1 V5-N2-J2-K2-

Synchronisation: Ssm

oN = sn = Sync. Status message on

Ssm oN : Mux will take into consideration the information available at S1 Byte (of MSOH) & automatically will select Best value, from all the available values Ssm Off :It is on manual - Mux will ignore the information available at S1 Byte (of MSOH). -no Quality level,Hierarchy will not have any control. Tx Over ride = to = Clock quality we put will be taken as information available from S1 byte & will be taken into consideration. Rx Over ride = ro = whatever clock quality level received will be ignored .what ever we put will be taken as information available from S1 byte & will be taken into consideration. Reversion on= r

= In case of failure of clock quality of 1st priority fails, it will change over to

clock quality of 2nd priority & as soon as 1st priority quality will be available, Mux will change over to clock quality of 1st priority Reversion oFf =f

= Once changed over to 2nd priority ,it will not change over to clock quality

of 1st priority, even though it is available. force oN = in case when ssm is off-Mux has changed over to s7-1 from s6-1 (as s6-1 has failed) Now it will not go back to s6-1 automatically-Even if s6-1 is o.k.in that case if we want Mux to change over to s6-1 we use force oN &then it will go to s6-1 forCe_off = When Ssm is oN & force is also oN ,at that time ssm on will not be active ,hence to make ssm active we have to forCe off.

104

SDH - STM-1 Frame Structure - Section Over

261 BYTES

AU4 POINTER MULTIPLEXER SECTION OVERHEAD

PATH OVERHEAD

9 BYTES

9 BYTES

REGENERATOR SECTION OVERHEAD

Heads

OFFSET J1 B3 C2 G1 F2 H4 F3 K3 N1

VC4 = 9 x 260 bytes + 9 (POH)=2349 2340 +9 = 2349

Section Over Heads ( SOH ) A section can be considered as one stage of end to end. It is defined as node to node transmission. A path may be made up of number of sections. One section may also be a Path. SDH reserves some extra capacity within the defined bit rate to carry information relating to section. The extra information associated with a section ( generated at one node & processed at the next node) is called Section Over heads (SOH). The section Over head allows control of node to node Transmission e.g Quality. It allows two adjacent node to talk with each other& to take action in case of Section Failure. The SOH also provides extra information channels- used for network Management Data Communication Channel. SOH information is further classified into RSOH & MSOH – Total 72 Bytes It is terminated at Regenerator function - 27 Bytes - (9x3) –Raw 1 to 3 of STM – 1 Frame MSOH - Multiplexer Section Over Head – 45 bytes-9x5 - (Raw 5 to 9 of STM-1 frame) MS – can access both –Multiplexure & Regenerators - but not simultaneously. • Multiplexure can access both MSOH & RSOH . • Regenerator – can access only RSOH but not MSOH • i.e.RSOH can be accessed by both Multiplexure & Regenerators,hence in our network we use RSOH at most of the places. • Hence in our network we use common RS- DCC / DCC-R so that the same channel can be accessed by both Multiplexure & Regenerator. • These OH’s carry various section related information for Network Management, Synchronisation, Fault management, etc.

105

REGENERATOR REGENERATOR SECTION SECTION OVERHEAD OVERHEAD AU4 POINTER

PATH OVERHEAD

Regenerative Section Over head – RSOH – 27 Bytes

PAYLOAD

RSOH A1

A1

A1

A2

A2

A2

Framing Byte 1

Framing Byte 1

Framing Byte 1

Framing Byte 2

Framing Byte 2

Framing Byte 2

Reserved for Media-OFC 00

E1 EOW

0

-

Reserved for Media-µW-00 e.g Error Checking

D2 DCC

B1 BIP

D1 DCC

J0

X Reserved for National / F1 Govt./ Channel for Emergency Service use RS Path Trace

provider use

0

-

D3 DCC

-

-

Section (as referred in NA)/ Regenerator Section (as referred in Europe) refers to a portion between a Multiplexer & a Regenerator or between two Regenerators. A AU-3

- RSOH

- Regenerator Section

Over Head comprises:

A1&A2:- Indicates beginning / starting of STM - 1 Frame - Used for checking the alignment of incoming STM -1 Frame –. It is composed of 3xA1 Bytes followed by 3 A2 Byte. J0: RS Path Trace for Entire STM -1 – This byte is used to transmit repetitively, a section access point identifier, so that a section receiver can verify it’s continuity with the indented transmitter. B1: Bit Interleaved Parity 8 (BIP 8)-The BIP-8 is computed over all bits of the previous frame & is placed in the B1 byte of the current frame.Used for Error Monitoring. E1 Order Wire : ( Engg. Order wire ) Can be used as a hot line Voice communication within the all Ring Network Element . Enables Node to Node verbal talk.i.e BTS to BTS / MCN F1: User Channel : -Reserved for User to define – for special maintenance by Service Provider D1-D3: Data Communication Channel –DCC - Communication Channel between Regenerator to Mux & Mux to Gateway Mux & to NNOC - Used for Element Communication –Alarms - controls – Monitoring & Administration For checking status of all NE by NNOC. Link CPU-1 to CPU- 2 will be through it. – It gives information about - neighboring Regenerator & Mux. (i.e. on LHS & RHS). – location of near by Gateway Mux & Router for communication control –with NNOC-can communicate alarm details also. X – Reserved for Hot line for Govt. use – Emergency like Train blast,Riot,Calamity like Flooding ,Earthquake ,tsunami - National Security Agency like RAW ,Defense

106

Multiplexer Section Over head - MSOH- 45 Bytes B2 BIP

B2 BIP

K1 APS

-

-

K2 APS

-

-

D4 DCC

-

-

D5 DCC

-

-

D6 DCC

-

-

D7 DCC

-

-

D8 DCC

-

-

D9 DCC

-

-

D10 DCC

-

-

D11 DCC

-

-

D12 DCC

S1 Sync

-

-

-

-

M1

E2 EOW

AU4 POINTER MULTIPLEXER SECTION OVERHEAD

PATH OVERHEAD

B2 BIP

PAYLOAD

X - Reserved for National / Govt./ Emergency use

MSOH

MSOH comprises: B2: BIP24 - Used for Error Monitoring by Receiver – Transmits REI to Transmiter on Error detection. K1&K2:- Automatic Protection Switching - APS signaling coordination for APS (Within 50 mili sec.) D4-D12: Data Communication Channel –DCC Communication Channel between Mux to Mux in the same area & Mux to Gateway Mux & to NNOC - Used for Element Communication – For checking status of all NE by NNOC. Link CPU-1 to CPU- 2 will be through it. – It give idea about - neighboring Mux. (i.e. on LHS & RHS). – location of near by Gateway Mux & Router for communication control –with NNOC. - -can communicate alarm details also Used for Communication – Alarms - controls – Monitoring & Administration

S1: Synchronization Status - Used to transmit the level of synchronization. - Which type of clock is available to Data M1 : Multiplexer Section Remote Error Indication - REI E2: Engineering Order Wire - can be used as a hot line Voice communication within the Ring elements –Regenerator to Regenerator & R to Mux & so on . N8 – 2Bytes – Tandem Connections Blank boxes means –At present not in use – kept for future requirement

107

Over Head Summary Details

RSOH-27

MSOH-45

1

Bip Error

B1 – BIP-8 1 Byte

B2 – BIP24 Bytes

2

REI

3

Path Trace -

4

Tandem Connection

N8

5

APS

K1,K2

6

Sevice Provider Maint.

F1 – 1 Byte

7

Frame Alignment -

A1-A2 – 6 Bytes

8

Engineering. Order Wire

E1 – 1 Byte

10

Data communication Chanel

D1-D3 – 9 Bytes

11

Sync. Status

9

Used for Error monitoring by Receiver

M1

Path Trace so that Receiver can verify it’s continued connection with Transmitter

J0 – 1 Byte

Indicates beginning of STM Frame

R to R & R to M & so on E2

R to M & M to M & so on

D4 to D12

Communication – Alarms - controls – Monitoring & Administration

S1

108

All Over

Head

Summary

Details

L-POH

H-POH – 9 RSOH-27

1

Bip Error

V5 - 1&2nd

B3

2

REI

V5 – 3rd

G1

3

RFI

V5 – 4th

G1

4

Signal Label -

V5 – 5-6-7

C2

5

RDI-

V5 – 8th

G1

6

Path Trace -

J2

J1

7

LOS, TIM,LOP

MSOH-45

B1 - 1 Byte M1

J0 – 1 Byte

Tandem Connection

N2

N1

N8

8

APS

K4

K3

K1,K2

9

POINTER

V1,V2

H1 , H2

10

Equipment Vendor

F2

11

Multi frame no.

H4

12

Sevice Provider Maint.

F3

13

Frame Alignment - LOF

A1-A2 – 6 Bytes

14

Engg. Order Wire

E1 – 1 Byte

15

Data comm

D1-D3 – 9 Bytes D4 to D12

16

Sync. Status

F1 – 1 Byte E2 S1

109

What is a Path Overhead ? Section Over head Active Higher Order Path - Mumbai to Delhi End to end connection from Source Aggregate Card to Destination Agregate Card. Higher Order Path over head inserted at Mumbai & Will be checked / Active at Delhi only Lower Order Path Over Head Active Lower Order Path Over Head Inactive -

Ahmadabad Mumbai

STM-16

A C PLM

Delhi

STM-16

A C

VC12

TC

TC

Tributary

VC12

Tributary

DAKC

Gurugaon

A circuit is configured by allocating the Payload a VC (KLM number) and making Add-drop or Through connections at relevant ADM’s. At both the terminating ADM’s, Add-drop connection is made by associating the VC to a relevant Tributary port and Aggregate port. Through connection is made by associating the VC of one Aggregate port to the other.

110

Module Review – Exercises – 7A 1.

All payload in SDH is carried through a ……………….. Container.

2.

VC-12 carry ….. Payload bytes , ……… Stuffing bytes & …… POH bytes

3.

……… consecutive VC-12 frames form a Multi Frame

4.

3 TU-12 form a …………… and ………… TUG-2 form a ……………

5.

K300 means a VC-…., K213 means a VC-…...

6.

A VC-4 has ……… X ……….. bytes, in which ……….. bytes are POH

7.

In India we follow _ _ _ _ _ _ standard.

8.

STM-1 is _ _ _ _ bytes per 125 microseconds i.e. _ _ _ _ _ _Mbps.

9.

In PDH –Capacity with Copper is Limited to _ _ _ Mbps.

10. Clock Accuracy of PDH system is

_ _ _ ppm & SDH is _ _ ppm.

11. Lower order POH are inserted by _ _ _ _ _card & Higher order POH POH are inserted by _ _ _ _ _ &Section Overhead are inserted by _ _ _ _ _ card. 12. Information carried by the network is known as _ _ _ _ _

111

Module Review -

Exercises – 7 B

1.

Path is …….. to ……. connection, MS is connection between two ……….

2.

J0 in RSOH is ………….………… for the entire ……………….

3.

MSOH is …………….. bytes & RSOH is ………..Bytes

4.

Sync. status are carried in … …… byte, while - - - - - is reserved for Service provider

5.

K1/K2/K3/K4 is used for _ _ _ _ __ _

6.

E1/E2 are for Engineering Order wire i.e. for _ _ _ _ _ _ _ .

7.

STMSTM-1 means _ _ _ E1 = _ _ _ _ TugTug-2 = _ _ _ _ _ TugTug-3.

8.

BIP error is indicated by _ _ _ _ _ _.

9.

N1/N2 is used for _ _ _ _ __ __

112

Protection Techniques Module 8

113

Dedicated Protection – SNCP / PPS P a t h

Sub Network Connection Protocol / Path Protection Switching

A

B

P r o t e c t i o n

F

S w i t c h i n g

STM-16 RING

16 VC4 Forward Paths

16 VC4 Protection Paths

E

( P P S )

C

r e f e r s

D

In Dedicated ring –Switch over at Terminating End t o

Automatic Path Switching will occur within 50 mili seconds.

Two levels of protections 1) Card level 2) Path level It can be 1:1 or 1:n Starting point is referred as Transmitting point. End point is referred as Tail end – Receiver point – End point

PATH LEVEL Protection Also Known as Path Protection Switching (PPS) Dedicated is having 1:1 Protection SNCP – Sub network Connection

Protocole - Revertible

SPUR connection :- MSP - Multi section Protection For path A-B-C-D

Protection Path is Path A-E-F-D

B&C & E&F is pass-through Path From A to B to C to D carries 16 VC4 From A to E to F to D carries 16 VC4 But normally D will receive from ABCD side only – (i.e. one way valve function) Even though AEFD remains loaded –It remains standby - Normally D will not accept any data from that side. Only in case of any failure on ABCD side it will accept from AEFD side.& entry valve for BC side gets closed

114

Dedicated Protection Sub Network Connection Protocol - SNCP A

B

Swich over occurs at Terminating ADM -RX

Channel 1-16

F

STM-16 DP RING C

E Channel 1-16

D

In Dedicated ring –Switch over at Terminating End –APS will occur within 50 mili seconds.

Only in case of any failure on ABCD side it will accept from AEFD side.& entry valve for BC side gets closed Dedicated

- -----Nortel - PPS ------Marconi – SNCP--– Subnet connection Protocol- - Revertible

D will convey A - by means of K1-k2-k3 that that I have switched over to – AFED- as I am getting Excess error /Degraded signal. Pl. note & do the needful.

115

Multiple Section - Shared Protection Ring – M S S P RING A Channel 9-16

Active Path

B

F STM-16 M S S P RING Ring Capacity = (Capacity / 2) x N

C

E Reserved Path

D

Whatever be the mechanism of Transport, all good network need to have some Protection. The scheme RIC uses for it’s Backbone is called Shared Protection Ring. Take a ring with 6 MCN’s. Assuming a STM-16 Ring is established, 1-8 channels (of STM-1 bandwidth) are used in the forward path. Each MCN to the next can be independently operated so we get a total of 6*8 = 96 paths. If there is a fault between MCN B & C (due to Fiber cut, Card Failure, etc.) then Traffic at B is diverted to the reverse path (channel 9-16). If a TU was to travel from A to D, in this case it turns back at B, to A. A passes it on to F, as the TU is on the reverse path. F passes on to E and E onto D. Even D passes it onto C, because it’s on the reverse path. The TU reached C, where it is diverted to the forward path (Both B & C would know that there has been a failure in the B-C forward path). Thus the TU comes onto the forward path and reaches D, where it is accepted.

1) 50% bandwidth is used. 2) 50% is reserved for Protection 3) Shared protection ring data exchange takes place between each node. 4) No nodes are pass through. 5) Revertible

116

Multiple Section Shared Protection Ring - M S S P RING A

Channel 9-16

B

Active Path

F

STM-16 M S S P RING Ring Capacity = (Capacity / 2) x N

C

Reserved Path - Now Active

E

D

Shared protection will have one ring path - reserved - remaining inactive normally capable of caring half the capacity. It becomes active only when ever fiber breaks. It serves as a connecting link between isolated node & maintain the continuity. This method serves the purpose till 1st break only. Terminology BLSR – Bidirectional line switch ring,-two fiber – shared Protection MSSPR – Multiple section share protection ring.- Revertible Whatever be the mechanism of Transport, all good network need to have some Protection. The scheme RIC uses for it’s Backbone is called Shared Protection Ring. Take a ring with 6 MCN’s. Assuming a STM-16 Ring is established, 1-8 channels (of STM-1 bandwidth) are used in the forward path. Each MCN to the next can be independently operated so we get a total of 6*8 = 96 paths. If there is a fault between MCN B & C (due to Fiber cut, Card Failure, etc.) then Traffic at B is diverted to the reverse path (channel 916). If a TU was to travel from A to D, in this case it turns back at B, to A. A passes it on to F, as the TU is on the reverse path. F passes on to E and E onto D. Even D passes it onto C, because it’s on the reverse path. The TU reached C, where it is diverted to the forward path (Both B & C would know that there has been a failure in the B-C forward path). Thus the TU comes onto the forward path and reaches D, where it is accepted. As you can see even if any part of the forward path fails, the Ring is completed by the reverse path. This is called Shared Protection Ring, because in normal course channel 9-16 can be shared with some low priority and high delay tolerant use. C will convey B - by means of K1-k2-k3 that that I have switched over to – Protection Ring - as I am getting Excess error /Degraded signal. Pl. note . & in the same way – (as B is not receiving any signal ) B will convey to C

117

Time Synchronization Module -9

Synchronisation: Ssm oN = sn = Sync. Status message on Ssm oN : Mux will take into consideration the information available at S1 Byte (of MSOH) & automatically will select Best value, from all the available values Ssm Off :It is on manual - Mux will ignore the information available at S1 Byte (of MSOH). -no Quality level,Hierarchy will not have any control. Tx Over ride = to = Clock quality we put will be taken as information available from S1 byte & will be taken into consideration. Rx Over ride = ro = whatever clock quality level received will be ignored .what ever we put will be taken as information available from S1 byte & will be taken into consideration. Reversion on= r = In case of failure of clock quality of 1st priority fails, it will change over to clock quality of 2nd priority & as soon as 1st priority quality will be available, Mux will change over to clock quality of 1st priority Reversion oFf =f = Once changed over to 2nd priority ,it will not change over to clock quality of 1st priority, even though it is available. force oN = in case when ssm is off-Mux has changed over to s7-1 from s6-1 (as s6-1 has failed) Now it will not go back to s6-1 automatically-Even if s6-1 is o.k.in that case if we want Mux to change over to s6-1 we use force oN &then it will go to s6-1 forCe_off = When Ssm is oN & force is also oN ,at that time ssm on will not be active ,hence to make ssm active we have to forCe off.

118

Clock †

Primary Reference Clocks (PRC) …

†

Types

PRC – Type 1 – Quality Level – 2 ( Hyd – Banglore – Delhi) - Atomic Clocks - Cesium Clocks – Long term accuracy – (0.000 01ppm) – 10-11 - PRC 1 – Master – Hyderabad - PRC 2 – Hot Standby – Banglore - PRC 3 – Backup – Delhi –

GPS Clocks PRC – Type 2 - (Mumbai – Kolkatta) - makes use of GPS satellites . - Gets the clock from U S Defense - Out of 24 Satellites – 3 will be available any time for synchronization - transmitting in the microwave range (1.5GHz) - GPS 1 & 2 – Backup - Mumbai & Kolkatta

†

Secondary Source Unit – SSU – 40 nos. - SSU required after every 20 nodes. – Maximum NE in such chain should not be more than 60 - There are such Such 40 SSU sites.

†

Internal Clock - Own Internal Clock - Quality Level – 11 - Q L – 15 – Do not use.

In case of Atomic clock other clocks are Hydrogen Clocks – Very high Accuracy – very costly Rubidium clock - Short term Accuracy -QL after ssu-1 = 4 & QL after ssu-2 = 8 (maxm SSU not more than 10 in 60 NE link)

SSU removes Wonder ( slow variation ) i.e. below 10 Hz & Jitter ( Fast variation ) i.e. Above 10 Hz With SSU - K x n = <_ 60 Where K = no of nodes &

n = 1 for PRC type 1 (Atomic clock ) = 2 for PRC type 2 (GPS clock )

Stratum 3 =4.6 ppm All transport Equipment ( TN1x , TN 4x , TN 16x )gets data having clock PRC Type – 1 , QL – 2 , from Hyderabad Atomic clock. Other Access equipment (voice data , Video ) get the clock from these Transport Equipment. At BTS –transport equip. TN-1C can not transmit the clock, Hence Access equipment at BTS uses GPS clock. In each area 1 or 2 BTS is provided with a GPS clock system & those BTS transmits the clock to all other BTS..All Access equipment at BTS uses this clock.

119

SSM - STM-N ring [Single External Source]

Q L 2 = Atomic clock In the example of Figure 7-2, synchronisation is derived from the Primary Reference Clock (PRC). The PRC is the external (EXT) source with a QL=2 at TN-1X(A). The other TN-1Xs in the ring have their hierarchy set to derive synchronisation from the counter-clockwise TN1X in preference to the clockwise TN-1X (that is, on their B ports in preference to A). The QL = 2 clock is transmitted on all STM-N ports for the TN-1X, with the exception of the return port of the synchronisation source, on which QL = 15 (“do not use for synchronisation”) is transmitted. This prevents closed synchronisation loops. Note: Before the PRC signal was introduced, all four TN-1Xs would have used the default QL setting of 11, which indicates the use of an internal oscillator (INT). If a fibre break occurs, the TN-1Xs after the break will send a QL = 11 in the counterclockwise direction. The last TN-1X in the ring will switch to the higher quality clock (QL = 2) being sent from the TN-1X with the PRC in the clockwise direction. The QL = 2 clock is then available from its clockwise port, so moving in a clockwise direction around the ring each TN-1X will switch to the PRC QL = 2 clock. The ring will then be synchronised to the highest available quality clock. Q L – 2 – Quality Level – Atomic clock at Hyderabad -3 - 8-

- Atomic Clock at Banglore – will be active if Hyd. Clock fails. -GPS – Global Positioning System clock-Mumbai,delhi, Kolkatta

120

Simple Ring - 2 Reference Sources

Synchronisation is derived from the Primary Reference Clock (PRC). The PRC is the external (EXT) source with a QL=2 at TN-1X(A). There is also a Secondary Reference Source (SRC) which is also external and has a QL = 3 at TN-1X(B). The other TN-1Xs in the ring have their hierarchy set to derive synchronisation from the counter-clockwise TN1X in preference to the clockwise TN-1X, that is, on their B ports in preference to A. The QL = 2 clock is transmitted on all STM-N ports for the TN-1X, with the exception of the return port of the synchronisation source, on which QL = 15 (‘do not use for synchronisation’) is transmitted. This prevents closed synchronisation loops. In the event of a failure of the primary reference source the TN-1X with the primary source switches to an internal clock with a QL = 11. This will propagate around the network until it reaches the TN-1X with the secondary reference source which will switch to the SRC and transmit a QL = 3. This will then propagate around the network in a clockwise direction with the other TN-1Xs synchronising to the secondary reference source. Note: The hierarchy on the TN-1Xs with the external sources are set so that one synchronises in a clockwise direction around the ring and the other in a counter-clockwise direction. This is to prevent synchronisation timing loops. If QL – 2 fails QL-3 will be active & will transmit 3 on both side. Generally system follows high level clock If both clock are same – Then it will follow Hierarchy table.

121

Network Management Module - 10

122

Add Drop Multiplexure - Mux - ADM Higher POH B3-J1-N1-K3

Lower POH V5-J2-N2-K4

TRIB.

TRIB.

Left West Trib Card

Trib. Card

CPU

P L M

A

AGGREGATE (Adds MSOH / RSOH) Card AGGREGATE Card

B Right East

PDH & Lower bit rate SDH signal can be extracted from or inserted into high speed SDH bit stream (aggregate ) by ADM

In a Ring each node is called a Add-Drop Multiplexer (ADM). An ADM have grossly three parts: 1. Tributory

Card : interfaces with the non-ring nodes to bring in Traffic Adds Lower order Path Over Head.

2. Pay load Manager: Some intelligence is required to take care of who has entered from where & Where he is getting down.PLM acts as a Manager for such activities . Manages multiplexing & de-multiplexing activities. Adds Higher order POH.

Active PLM Provides the Local Oscillator 3. Aggregate

Card: Total information carried is known as Aggregate. It interfaces with the OFC Ring. Adds as per MSOH/RSOH as per CPU

Network Elements: 4. Amplifier:

It amplifies amplitude & time interval of Pulse.

5. Switch:-

Connects caller party with the Called party as & when required. (Call to call basis).

4. Cross connects:

It connects Payload of one ring with Payload of other ring –for longer time . Dx: Digital Cross connect –Nortel – Low capacity 140 Gbps HDx :- High capacity – 640 Gbps - Nortel Oxc – Optical cross connect OMS – 16 84 -Marconi Cross connects enables interconnections of diff. network segments i.e. VC4 of one ring is broken up required E1 (Payload) of that ring is put in VC4 of the other (desired) ring along with other E1. After addition of Overhead it 123 b A

Nortel TN-1C Unit

124

View of TN1C SIA

125

View on TN1C

126

View of TN 1X

127

View of Aggregate Card

128

Key Concepts : Switching Network without switching

Network with a switch

Switch

• Requires n(n-1) / 2 transmission links • Requires n transmission links • 15 independent links would be required • Only 6 independent links would be in this example to allow calling between required when a central switch is used users

Switch not only reduces transmission cost but also reduces the complexity of connecting subscribers. Here subscribers have complete control on information flow to a subscriber. Similar concept is further extended to route subscribers traffic to long distance exchanges by taking calls through exchanges arranged in tandem. R2MFC – Registered & Registered Multi Frequency Channel. STP – Signal Transferring point – All switches are connected to STP SCP – Switch Control Panel –available at STP for Database-passes data / information ( details of caller & Receiver party ) as & when required by STP . CCS7 – Common Channel Signaling version-7 In Dx connections are made for longer time. In switches connections changes from call to call.

129

Regenerators - Amplifiers †

It regenerates the time & amplitude relationship of the incoming data signal that have been attenuated& distorted by dispersion.

‰

It removes distortion in amplitude as well as in time interval.It’s function is Reshaping – Retiming - & Retransmitting

130

Ring Elements & Terminologies ADD DROP MUX POH

POH

STM-N RING 2

STM-N RING 1 DX - CROSS CONNECT

POH POH POH

POH

POH POH

DX – Required where more then 1 ring exists. It Connects Pay load of one ring with Payload of other Ring This is how a STM ring function. To start with lets take one of the Nodes, generating all the packets, complete with POH and other details. The container reaches the next station where looking at these information, it is passed on to the next node. There some one the boxes are downloaded and some are uploaded. The container moves on and the process in repeated at the next node(s). Much like a Railway track with several stations. As a Train passes by, some get on board and some alight at each station and the train moves on. These stations/ nodes are called Add-Drop Multiplexers and this railways is called a STM ring. Nortel classification Dx = Digital Cross connect = capacity 140Gbps HDx = high Cross connect

= capacity = 640Gbps

Macroni – it is known as OMS 1684 – 60 Gbps There could be more than one STM ring and there need to be a node which can exchange containers between these rings. Much like a Railway junction. Such a node is called a Digital Cross-Connect..It connects Pay load of one ring with Payload of second ring. In Dx connections are made for longer time. In switches connections changes from call to call. Oxc = Optical cross connect – not commercialized yet

131

SDH Backbone Rings Jallandhar

Ambala 6 Lucknow

Delhi Jaipur

Ahmedabad

1A

Bhopal

3A Allahabad

5 Jamnagar 3B

Surat

Kolkata

1B Nagpur

Mumbai

Bhubaneshwar 3C

1C Pune

Hyderabad

Vijaywada

Total of 22 DX Add/Drop Locations 2.5G ADM 2.5G SDH Ring

7 Bangalore

2

10G ADM

Chennai

10G SDH Ring

4 Coimbatore

Ernakulum Trivendrum

Madurai

At the National level RIC has established 7 very high bandwidth Transport Rings, called National BackBone/ Long Distance Rings. Practically there are 11 rings as Ring 1 and 3 comprise 3 rings each (1A, 1B, 1C & 3A, 3B, 3C). These Rings are so designed that all major cities get enough bandwidth and not too many cities come on the same ring. Also having these 11 rings provide enough alternative routes in case of failure in one section. These rings traverse all the 18 circles, touch all major cities and cover about 90% of Indian population. Established (read utilised) Bandwidth of these rings are at 10 Gbps, but that’s just tip of the iceberg compared to what we can achieve. What gives these rings such gargantuan bandwidth – OFC. How – we will see later in this module. As stated earlier, these rings connect 22 Core MCN’s with 17 ILT’s at this moment. From these rings, at these 22 MCN’s, emerges several Metro Access Rings, which connect other small cities and towns to the NBB.

132

Network

Elements

1.

Optical Fiber Cable_ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ Siemens, Corning

2.

OTDR

Tectorinx

3.

Fiber Management System

Agilent

4.

SDH Equipment -- - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - -Nortel, Fibcom

5.

DWDM Equipment

Nortel

6.

Sync Equipment

Datum

7.

Router - STM -256 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Cisco – Juniper

8.

Transport –

TN1C at BTS – STM -1

Nortel

TN1X – STM- 1 TN-4X –STM 4X & TN 16 X / STM-16X Small mux equivalent to TN1C) N6110 – STM-1 - - - - - - - - -Tejas N6130 - STM - 16 N – 5200 – STM N 6500 – 10 Gg / STM 64 9

Cross Connect - Dx -140 Gb/ STM-64 - - - - - - - - - - - - - - - -Nortel HDx -1280 Gb / STM-64 / 80 λ Huawei T- 6040 16λ & 6130 – 40 λ OMS 1684 / 64 / 54 / 40 – - - - Marconi - - - Stm 64 to STM-4 (16 port STM- 1)& 4 port – STM-16 card Single port – STM -64

Cross Connect - Dx -140 Gb/ STM-64 Cross connect is connected with more then one links –each link having capacity STM-64. i.e. Cross connect Equipment must be capable of controlling all of them simultaneously & that capacity is 140 Gb. (e.g.A train may be having capacity to carry 1000 passengers but the station should have capacity-much more than that train - to control many trains at a time.) The backbone transport provides for connectivity between different LDCAs, SDCAs and cities. In addition interconnect is extended for other NLD, CSP and FSP networks. The core network comprises fully meshed, 7 primary and 14 secondary nodes. Physical architecture of the Core Network comprises of two-tier ring network – Express Ring & Collector Ring. Traffic between major metros and all major node cities is transported on the high capacity transport path – The Express Ring. Traffic from the other LDCA’s (Long Distance Charging Areas) is transported on The Collector Ring. The ring topology provides necessary protection to traffic in terms of alternate path in case of breakage of the optical fibre or equipment failure thus ensuring smooth undisrupted operation of the network. The functions of the Core-Backbone Network are as follows: Provide connections, either on permanent basis or temporary basis for the transfer of information in a cost effective, reliable and speedy manner · Routing – which way to send the information · Transport – how the information is carried

133

Network

Elements

Cisco 7507 ‐ Cor e IP r outer Cisco 3662 ‐ Aggregation IP r outer Cisco 3745 ‐ Aggregation IP r outer Cisco 3631 ‐ Access IP r outer

Cisco Routers

Cisco Sw itches

Nortel

5 25 19 429

Cisco 3725 ‐ ILD IP r outer

3

Cisco 2610 ‐ Access IP r outer

2

Cisco 2611 ‐ Access IP r outer

10

Cisco 2610 LMDS

98

Cisco 2611 LMDS

239

Cisco 2610 Micr ow ave

10

Cisco 2611 Micr ow ave

38

Cisco 3662 ‐ Aggregation OSI r outer

22

Cisco 3631 ‐ Access OSI router

71

Cisco 2611 ‐ Access OSI router

29

Cisco 4507 ‐ Aggregation Sw itch

10

Cisco 4503 ‐ Aggregation Sw itch

6

Cisco 3550 ‐ Agg + Access Sw itch

38

Cisco 2950 ILD Access Sw itch

3

Passpor t 8600 Sw itch

6

Allied Telysyn AT 745 ‐ Micr ow ave

39

Total DCN Elements being monitor ed 

1102

134

Ring Elements & Terminologies

Payload Manager

Payload Manager

In a Ring each node is called a Add-Drop Multiplexer (ADM). An ADM have grossly three parts: Tributory

Interfaces with the non-ring nodes to bring in Traffic

Payload Manager

Manages multiplexing & de-multiplexing activities.

Aggregate

Interfaces with the OFC Ring

135

Intra city Network

MCN

Payphone

ADSL

ISDN

MAN

MAN

STM 4 / 1

ADM

Building Access Ring

MCN

Metro Access Ring STM 16 / 4

STM 64 / 16

National Backbone

ILT Switch

BTSCT ADM

SHDS L

RTU Fiber To The Building (FTTB) STM - 1 RTU

BAN

PBX

BAN Netman

Phone Computer

Video (348k)

MCN

From MCN’s on the NBB National Back Bone / NLD National long distance . From MCN’s on the NBB, we get Metro Access Rings - like state highways emerging from the National highways. These MAR carry the traffic to over 1100 cities and town of the country. . Bandwidth of these MAR are in the range of 625 Mbps – 2.5 Gbps and upgradeable further with little change in the infrastructure. Nodes on MAR are known as MAN (e.g. SRM (Parel) , Andheri MIDC , Chembur ). From MAN ( Metro Access Nodes) on Metro Access Rings , we get Building Access Rings (like Main Roads inside a City or Town.) These BAR connect various Building Access Nodes. At the BAN, we have the Central Terminals (CT’s) or the Base Transceiver Station (BTS) Modcel, The CT’s connect several (14 as of today) Remote Terminal Units (RTU’s) which in turn provide Fixed Access. The BTS covers all the Mobile Stations (MS) within it’s radius of coverage, thus providing Wireless Access. Connection right up to the RTU is - through OFC (this is therefore called Fiber To The Building), thus providing enormous bandwidth. These networks are capable of providing both Narrow Band & Broadband services. Transport element on MAN & BAN is known as ADM Ring capacity – FTTB – STM-1 , BAR - STM 1 to STM – 4 MAR - STM 4 to STM – 16 NBB - STM - 64 136

SDH

D X C

Jallandhar

D X C

Backbone Rings

Ambala

Reliance Backbone (DWDM) Ring 6Rings D X C D X Jaipur C

Ahmedabad Ring-5

Indore D X C

Jamnagar

Dhule

Ring 1B

D X MumbaiC

Ratnagiri

D X C

Surat

Pune

D X C

Bhopal

D X C

Nagpur

Ring 1C

D X C

Ring 7 X

X

Calicut

Mysore X

Trichur

X

D X C

D X C

Ernakulam

Allahabad D

Ring 3A

X C

Jabalpur

Kolkotta Ring 3B

Hyderabad

Ring 3C

D X C

Bhuvaneshwar D X C

Salem

D X C Bangalore

D X C

Ring 4

Coimbatore Madurai D X C

D X C

Vijaywada Ongole

Anantpur Ring 2

Hasan Ring 7

Ring 8

D X C

D X C

D X C

D X C

Manglore

Lucknow D X C

D X C

Ring 1A

D X C

Delhi Agra

D X C D X C

Chennai Pondicheryi

D X C D X C

Thanjavur

Nagercoil

At the National level RIC has established very high bandwidth Transport Rings, called National BackBone/ Long Distance Rings. Practically there are 12 rings as Ring 1 and 3 comprise 3 rings each (1A, 1B, 1C & 3A, 3B, 3C). These Rings are so designed that all major cities get enough bandwidth and not too many cities come on the same ring. Also having these 12 rings provide enough alternative routes in case of failure in one section. ( Self healing criteria) ) These rings traverse all the 18 telecom circles -,227 LDCA,- 565 SDCA, extending wireline connectivity to 138 cities and wireless connectivity in 578 cities. touch all major cities and cover about 90% of Indian population.

Resiliency Links 1) Surat – Dhule - Indore – Bhopal – Jabalpur - Kolkata 2) Jaipur – Agra – Lucknow 3) Ring-2 - Anantpur – Ongole 4) Ring 4 – Salem – Pondichery 5) Ring 8 to 7 – Manglore Hasan 6) Ring 8 to 7 – Calicut - Mysore 5) Ring 8 to 4 – Trichur (Kerala) - Salem

137

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•Out of 48/24/12 fibers in a cable,only 2/4 fibers are usedrest remains unused i.e. Dark Fibers.

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My i a g a m

P o rb a n d e r

Ak b a r p u r

a M

Ra n c h i

P a d ra

Bh a d t h a r

$ Ú

$

U rw

a

Ú

V a d o d a ra

Ú

Ú

Re w

Ú

o a s a d

n a d h i Nag a r

N

a d a

Ka t n i

Ú

M

A h me d a b a d

h o l k a

a rb h a n g a

a rn a u t

h a ri f

Ú

m i a t n a g a r

An il a

D

$

b d i

Ú

Sa y a l

%

Ra k j o t

Bi h a r S

Dn i a ra

$

Sa g a r

%

Ú Ú

Ka l o l

M

$ Ú

L m i

$

%

J a mn a g a r

H

Va ji p u r

Ú ÚÚ % Ú Ú % % $ Ú $ Ú ÚÚ Ú Ú Ú Ú % ÚÚ Ú Ú

Sa n a n d

K h a m b h a il a

Ú

Ú

u c h

Ú I d a r

Ú

Vs i n a g a r

%

$

Ú % Ú

d a i p u r)

Sd i h p u r

Ú

H

$

D u r g a w a ti

%

D

%

M u z a f a rp u r

h a n da u l i

Na w

Pa a l n p u r

Ú Ú

C

Pt n a a

$

Ú Ú

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N a th d w a r a

Me h s a n a

%

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Ú Ú

Ú

a n d

Ú Ú Ú % Ú

% Ú Ú

Ú

Al a h a b a d

Ú

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Ra s j a m

Da n ap u r

%

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Sa n i i

%

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T ru i c he n d u r

Ú

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R

a m a n a th p u r a m

Krishna

•12, 24, 36, & 47th used for FMS ( Dark Fibers).FMS takes Periodic test automatically& in case of any abnormality reports. & Cuts will be noticed

This is our Reliance India Roadmap. It’s a mega network of 105 000 km of OFC highway connecting 12 rings,227 LDCA, 565 SDCA, covering 18 telecom circles, extending wireline connectivity to 138 cities and wireless connectivity in 578 cities. Business conducted in these cities constitutes 80% of India’s GDP. It is necessary to monitor the health of such a huge network . This is done by monitoring the health of Dark Fibers by means of Fiber Monitoring System. To the user it means how much competitive rates she/ he pays for a Local or STD call or on internet how fast is the download of an interesting article or favorite song. The core rings connect 22 Core MCN’s with 17 ILT’s at this moment. These are our Life-lines. The subtended rings interconnect some of these MCN’s and function like the Bypasses. Like how healthy you are in indicated by how well your heart is functioning and how good is your blood circulation, similarly the health of a telecom network can be measured by how is the reliability of these transport network is & how much bandwidth these transport network can handle . Like multiple lanes of Highways, Transport network provide bandwidth which decides how much traffic (read how many calls) can be carried. To the user it translates into how much she/ he pays for a short distance or long distance call or how fast is the download of an interesting article or favorite song. This module we will see how we live up to that challenge.

138

Reliance Optical Network - International

SA

NY

SG TY

LN, PR, FR AL

JD, TH, MU

HK

International Submarine Cable – Under Water - (Flag Telecom) • 22 Countries, 44 PoP’s, 180 Carriers connected world over • 42,000 km route length • India - Presently: 15 STM-1’s, Mar. ’05: 39 STM-1’s • Forms a complete ring

FLAG Telecom develops and operates advanced fibre-optic global cable systems over which it offers a growing range of value-added network services. It operates a global network and provides customers with connectivity to most of the major business centres around the world. FLAG Europe-Asia is the world's longest privately funded undersea fibre-optic cable system stretching more than 28,000km from the UK to Japan with landing sites in 13 countries FLAG Atlantic-1 is the world's first multi-terabit transoceanic dual cable system providing a fully protected city-to-city service between London, Paris and New York. FLAG North Asian Loop has been designed to support the strong growth in intra-Asia Internet traffic and provides intra-regional, city-to-city connectivity between Hong Kong, Seoul, Tokyo and Taipei.

139

Network

Detail – RIC Nodes / Plants

Inter city – NLD - NBB Backbone Network Total Network MCN IS Preside Server

: 95,000 km. ( Inter city ) : 1,30,000 km : 260 out of which 198 are Maintenance Point ( MSC = 90 + 6 , ILT Switches = 22 ) : 206 : At Mumbai & Hyderabad

Intra - city Interconnection Network BTS

: 25,000 km. ( Intra city) : 12000

Wireless

: 565 Cities

Wireline

: 184 Cities

No. of Ducts in National Backbone: 4/6 HDPE ducts Laying of ducts –(20 meters from road center ) take care of all future rearrangements (eg. Road widening, bridge replacement, etc) Cable marker stones placed along the route at every 200 m Warning tape placed below 0.5m from the finished grade Tracer wire for ease of detection of fibre placed above duct Buried at 1.65m below the ground along the route (Protection against Rodent) Standardised location of manholes and handholes Man holes are spaced 4 km apart . Hand holes are spaced 1 km apart . Cable slacks have been kept in every manhole (15 meters) and handhole (10 meters) from maintenance point of view

140

The Core Backbone Network Ahmadabad Himatnagar

Udaipur

Ajmer

Jaipur

Gurugaon

A

D J

Baroda

Delhi

DX – Digital Cross-connect

Agra

LH – Optical Amplifier OM4200 – SDH ADM AXE10 – ILT (Integrated local tandem) Switch

Bhopal

OM4100, TN1X/1C – SDH ADM

Surat

Express Ring (DWDM) Collector Ring (SDH)

M

Access Ring (SDH)

H

Mumbai

Nagpur Hydrabad

Karjat

Lonawala

PUNE

Sholapur

The backbone transport provides for connectivity between different LDCAs, SDCAs and cities. In addition interconnect is extended for other NLD, CSP and FSP networks. The core network comprises fully meshed, 7 primary and 14 secondary nodes. Physical architecture of the Core Network comprises of two-tier ring network – Express Ring & Collector Ring. Traffic between major metros and all major node cities is transported on the high capacity transport path – The Express Ring. Traffic from the other LDCA’s (Long Distance Charging Areas) is transported on The Collector Ring. The ring topology provides necessary protection to traffic in terms of alternate path in case of breakage of the optical fibre or equipment failure thus ensuring smooth undisrupted operation of the network. The functions of the Core-Backbone Network are as follows: •Provide connections, either on permanent basis or temporary basis for the transfer of information in a cost effective, reliable and speedy manner • Routing – which way to send the information • Transport – how the information is carried

141

Area no. & Mac no. for Collector Ring 1-1 242

RING 1-1: DCN Design

481

1

4

Meerut

New Delhi

171

Bulandshahar Aligarh

1

251

Mathura

1

Kosi

2

Router

1 241 2

221 1

Hathras

DX

DELHI CITY NEs ER11S05 ER11S06 ER11S07 ER11S08

ER11S01 Primary: Delhi Backup: Jaipur

Ring 6 S12

5

172

111

Delhi City NE’s: OSI Area: 0005, 0006, 0020,0021,0022,0023

483

Ratangarh

142 2

16

331 1

66

Sikar

482

Ring 1-1 S4

Faridabad

484

Gurgaon

Bawal

Kotputli JhunJhunun

4

3

Palwal

478

222

Alwar

477

474

1 441

Padasali

1 251

485

Ghaziabad Router

281 1

Rewari

Chomu Bikaner

476

Area: 0001 Narnaul Sri Dungarpur

Nagaur

475

Nokha Mandi

Jodhpur

473

Router

Bhim

1

171

1 521

1 471

Beawar

221

1

2 111 OSI

631

Pali

Ajmer

DX

1

581

Soyla

551

Jaipur

Router

1

Kishengarh 1

JAIPUR CITY NEs ER11S10

Mohanpura

Dudu

Jaipur City NE’s: OSI Area: 0007

ER11S04 Primary: Delhi Backup: Bhopal

OSI Area: 0002 281 1

Agra

331 1

Dholpur

361 1

Morena

411 1

Gwalior

441 1

Mohana

411 471

TN1X / TN-1C

Rajsamand

1

Shivpuri

521 1

Lukwasa

551 1

Guna

171

111 1

Router 111 2

Chiloda AHMEDABAD CITY NEs ER11S11 ER11S12

DX Ahmedabad NE’s: OSI Area: 0008, 0024 Ahmedabad

1 581

1 551

1 521

644

Kota

636

635

OSI Area: 0009

Router

Jaora

1 471

441 1

411 1

361 1

Router

??? 331 1 2

631 1

`

Dhar

Biaora

1 251

Router

Kurawar Mandi

711 1

DX 281 1

Router

633

Indore

OSI Area: 0003

ER11S03 Primary: Ahmedabad Backup: Bhopal

637

661 1

Ujjain

117

638

Mandsaur

Ratlam

Visnagar

Vijapur

Kalol

643

Badanwar

Mehsana

Thandala(Jhabhua)

221 1

Sidhpur Dahod

118

Himatnagar Idar

Neemuch

Patan Modasa

Limkheda

251 1

Ratanpur

642

Sehore

Palanpur

581 1 Janjali

Aklera

641

Deesa

Rajgarh 634

Jhalawar

OSI Area: 0004

1 281

Godhra

Udaipur Risavdev

1 331

Mahuda

Router

Asta

OPTera Connect DX

Bundi

DX

Mavli

Dewas

361 1

Bhilwara

Vadiyar

ER11S09 Primary: Bhopal Backup: Ahmedabad

Chittaurgarh

TN16XE

ER11S02 Primary: Jaipur Backup: Ahmedabad

Jahazpur

TN4XE

Nathdwara

2 171

Router

Bhopal

Bhopal City NE’s: OSI Area: 0025

Mhow

Pitampur

Whole network is divided into diff. area & is given the area number by NNOC , Just like Pin code given by postal dept. In each area there will be number of Multiplexer / mux (60 to 100 maximum).Each mux is also given a particular number ( Mac no. ) Just like we give name/number to each house/Bldg.. Every area has a Router. The Mux nearer to the Router is known as Gate way Mux. Each Area has connectivity with 2 to 3 router & accordingly there can be 2 to 3 one Gateway Mux. Every Mux has to deal with the the nearest Gate way mux to give information or to collect instructions from the NNOC. Interface among the NNOC – Router & Gate way mux is through Ethernet For Network Management control –If NNOC wants some information or wants to pass on some instructions to particular Mux , then will pass on the message to particular Gateway mux through router giving area code & mux no. - Every Mux (except Gateway mux) can not talk outside their area.If they want to talk ,they can do so through Gateway mux only. NNOC controls the network through Preside Server. •Can talk inside the area only. • Total no. of area can be 60 to 100.

142

Module Review

Exercise -8

1.

TN1X is an STM-… ADM, while TN4Xe is STM-… & TN16Xe is STM-… ADM

2.

Rings are interconnected at the ………..…… MCN’s through …………………….

3.

- - - - - - - - connects Access to Switch, - - - - - - -- connects Switch to Switch

4.

ILD connection is through the ……….. Nw,

5.

Access rings are ………… & ………..

6.

The collective information carried through a ring is called …………………..

7.

Technology used by collector ring is _ _ _ & by Express ring is _ _ _

8.

Dedicated protection system (SNCP) is used for _ _ _ ring,& Shared protection system (MSSP Ring) is used for _ __ _ _ _ring.

9.

SSU are located after every _ _ _ _node & maximum node permitted are _ _ _

10. The clock at Hyd.,Banglore & Delhi is known as _ _ _ clock PRC type _ __ _ . 11. The clock at Mumbai & Kolkata is known as _ _ _ clock PRC type _ __ _ _.

143

Operation & Management Module - 11

144

What is a Path Overhead ? Section Over head Active Higher Order Path - Mumbai to Delhi End to end connection from Source Aggregate Card to Destination Agregate Card. Higher Order Path over head inserted at Mumbai & Will be checked / Active at Delhi only Lower Order Path Over Head Active Lower Order Path Over Head Inactive -

Ahmadabad Mumbai

STM-16

A C PLM

Delhi

STM-16

A C

VC12

TC

TC

Tributary

VC12

Tributary

DAKC

Gurugaon

A circuit is configured by allocating the Payload a VC (KLM number) and making Add-drop or Through connections at relevant ADM’s. At both the terminating ADM’s, Add-drop connection is made by associating the VC to a relevant Tributary port and Aggregate port. Through connection is made by associating the VC of one Aggregate port to the other.

145

Lower Order Path Over Head - Related to Alarms Summary Details

L-POH

Related alarms

1

Bip Error

V5 - 1&2nd

Receiver finds - Signal degrade TU ( 1 ppm)-Minor Excessive Error rate ( 1 bit / 1000bit) TU -Major

2

REI

V5 – 3rd

REI TU (Minor)

3

RFI

V5 – 4th

RFI TU (Major)

4

Signal Label

V5 – 5-6-7

PLM – Pay Load Mismatch (M), - Unequipped TU (M)

5

RDI-

V5 – 8th

Indicates presence of

6

Path Trace -

J2

TIM – Tracer Identifier Mismatch TU - (M) - Loss of Sequence TU - (C)

7

Tandem Connection

N2

8

APS

K4

MINOR Alarms - Lockout active TU – Forced switch active - Manual switch active

9

POINTER

V1,V2

LOP= loss of pointerTU , Loss of alignmentTU

13

Frame Alignment - LOF

14

Engg. Order Wire

15

Data comm

16

Sync. Status

TIM- Tracer Identifier mismatch, PLM –Pay Load mismatch

AIS- Alarm indication Signal OR All ones

146

Over Head Summary & Related

1

Alarms

Details

H-POH 9 Bytes

Related Alarms - AU

Bip Error

B3

Excessive Error Rate AU/STS (1 Error / 1000 bits) Signal Degrade AU/STS

2

REI

G1

HP-REI

3

RFI

G1

RFI AU / STS

4

Signal Label -

C2

HP- PLM Pay Load Mismatch , HP Unequipped / Unequipped AU / STS /

5

RDI-

G1

HP-RDI PLM-TIM

6

Path Trace -

J1

TIM AU / STS-Tracer Identifier Mismatch – HP - TIM

7

Tandem Connection

N1

8

APS

K3

Forced Switch is active AU/STS ,Manual switch Active Lockout Active AU/STS AU-LOP = Loss of AU Pointer

LOS, TIM,LOP

9

POINTER

H1 , H2

10

Equipment Vendor, lucent,Nortel

F2

11

Multi frame no.

H4

12

Sevice Provider Maint.

F3

Loss of Multiframe AU/STS

Loss of Sequence AU/STS

147

Over Head Summary MSOH - 45 Details

MSOH-45

Related Alarms

STM / OCn

2

REI

M1

MS - REI

7

Tandem Connection

N8

8

APS

K1,K2

14

Engg. Order Wire

E2

15

Data comm

D4 to D12

MS D C C Link Failure , Communication link failure

16

Sync. Status

S1

LSS – Loss of Sequence of Synchronization Time Generation Entry Free to run Time Generation Loss of Reference

MS-AIS = Multiplexure section AIS Far End Protection Line fail STM ? OCn Protection channel Match Fail Protection mode mismatch Protection Switch byte Fail Forced Switch is active AU/STS , Manual switch Active Lockout Active AU/STS

148

Over Head Summary Details

RSOH-27

1

Bip Error

B1 - 1 Byte

6

Path Trace -

J0 – 1 Byte

12

Sevice Provider Maint.

F1 – 1 Byte

13

Frame Alignment

A1-A2 – 6 Bytes

14

Engg. Order Wire

E1 – 1 Byte

15

Data comm

D1-D3 – 9 Bytes

RSOH – 27 & Related Alarms Related Alarms - STM / OCn

TIM – Tracer Identifier Mismatch STM /OCn

LOF- Loss of frame STM/Ocn

RS D C C Link Failure Communication link failure

149

Maintenance: Layered Alarm Surveillance

SDH Description LOS Loss of signal TSE Test sequence error (bit error) LSS Loss of sequence synchronization AIS Alarm indication signal Regenerator section OOF Out of frame LOF Loss of frame A1, A2 B1 Regenerator section error monitoring RS-TIM RS trace identifier mismatch Multiplex section MS-AIS Multiplex section AIS MS-RDI Mux section remote defect indication MS-REI Mux section remote error indication B2 (24 bits) Mux section error monitoring Administrative unit AU-LOP Loss of AU pointer AU-NDF New data flag AU pointer AU-AIS Administrative unit AIS AU-PJE AU pointer justification event High order path HP-UNEQ HO path unequipped HP-RDI HO remote defect indication HP-REI HO remote error indication HP-TIM HO path trace identifier mismatch HP-PLM HO path payload label mismatch B3 HO path error monitoring B3

OH Byte

A1, A2 B1 J0 K2 K2 M1 B2 H1, H2 AU includingH1, H2 H1, H2 C2 G1 G1 J1 C2

150

Maintenance : Layered Alarm Surveillance Regenerator Section Multiplexer Section LOS/ LOF

Higher Order Path

Lower Order Path

1 AIS

(J0) RS-TIM (B1) BIP Err. (K2) (B2)

MS-AIS MS-BIP Err.

(M1) (K2)

MS-REI MS-RDI AU-AIS AU-LOP

(C2) (J1)

1

1 HP-UNEQ JP-TIM

(B3)

HP-BIP Err.

(G1) (G1)

HP-REI HP-RDI

AIS 1 AIS

TU-AIS TU-LOP (H4) (C2)

1

AIS

LOM HP-PLM

(V5) (J2)

LP-UNEQ LP-TIM

(V5) (V5)

LP-BIP Err. LP-REI

(V5) (V5)

LP-RDI LP-PLM

1 AIS

AIS

PLM = Pay load mismatch LOP = Loss of Pointer LOS Loss of signal LSS Loss of sequence synchronization AIS Alarm indication signal , All ones Regenerator section LOF Loss of frame A1, A2 RS-TIM RS - trace identifier mismatch Multiplex section MS-AIS Multiplex section AIS MS-RDI Mux section remote defect indication MS-REI Mux section remote error indication B2 (24 bits) Mux section error monitoring Administrative unit AU-LOP Loss of AU pointer AU-NDF New data flag AU pointer AU-AIS Administrative unit AIS High order path HP-UNEQ HO path unequipped HP-RDI HO remote defect indication HP-REI HO remote error indication HP-TIM HO path trace identifier mismatch HP-PLM HO path payload label mismatch B3 HO Path error monitoring PLM – Pay load mismatch – RDI

J0 K2 K2 M1 B2 H1, H2 AU includingH1, H2 C2 G1 G1 J1 C2 B3 G1

151

REMOTE / Far End LOOPBACKS - Outward Checks for Continuity between two Mux

TRIB.

TC

AGGREGATE P L M

A1 A2

TC

FAR END Loop Back Outgoing port is Blocked. -Incoming data received at Receiving port from outside external Mux (node) is sent back to same MUX through that outgoing port. -This will check the continuity of path from outgoing port to External MUX to incoming port -During this time PLM continues to Receive also. STM-1 Aggregate Unit/STM-1 Tributary Unit Remote loopbacks When enabled, the STM-1 input data (after the STM-1 interface and prior to the section overhead termination) is routed to the STM-1 output (after the section overhead insertion and prior to the STM-1 interface), the normal STM-1 output being disabled. This loopbacks the data from the receiver to the transmitter. The STM-1 input data from the receiver is still processed by the rest of the unit. Local loopbacks When enabled, the STM-1 output data (after the section overhead insertion and prior to the STM-1 interface) is routed to the STM-1 input (after the STM-1 interface and prior to the section overhead termination), the normal input from the receiver being disabled. This loopbacks the STM-1 data towards the Payload Manager.

152

INTERNAL / Near End

LOOPBACKS - Inward

Checks for Internal continuity of Mux

TRIB.

AGGREGATE

TC P L M

A1 A2

TC

Internal Loop back Incoming / Receiving Port is blocked. -That port is used for returning outgoing databack to PLM Data going out from PLM (Outgoing data) out going port to is sent to incoming / receiving port to PLM -- to check the inside continuity of MUX -During this time outgoing also continues. 34/45 Mbit/s Tributary Unit (VC-3) Remote loopbacks When enabled, tributary input data (after the line interface but prior to line decoding) is routed to the tributary output (after the line coding but prior to the line interface). The tributary input data is still processed by the rest of the unit unless the ‘Local’ loopback is enabled. Local loopbacks When enabled, tributary output data (after the line coding but prior to the line interface) is routed to the tributary input (after the line interface but prior to line decoding). The tributary output data is still applied to the line interface and output from the unit unless the ‘Remote’ loopback is enabled.

153

Module Review

-

Exercises - 9

1.

RSOH faults are bundled and escalated as AIS to …………..

2.

Path protection can be dedicated or ……………….

3.

Path protection can be applied to individual ………………

4.

MS protection is for the entire ……………. over one ……………….

5.

Shared protection reserves …………. BW for the shared protection path

6.

A Sync Source Hierarchy indicates ………between two equally accurate sources.

7.

SQL= …if clock is traceable to PRC type I , …… if traceable to internal clock

8.

In a Sync chain there can be max ……….. NE , …………. SSU

154

THANK YOU

155