chapter02.sdh overview protection schemes & cpe

For BSNL internal circulation only.

E2-E3

E&WS

SDH Overview ,

Protection Schemes & CPE


WELCOME

• This is a presentation for the E2-E3 EW&S

Module for the Topic: SDH Overview ,

Protection Schemes & CPE

• Eligibility: Those who have got the

Upgradation to from E2 to E3.

• This presentation is last updated on 15-3-

2011.

• You can also visit the Digital library of

BSNL to see this topic.


SDH Overview

Understand PDH & SDH Hierarchy

SDH protection Schemes

CPE


Synchronization of Digital Signals

Synchronous,

Plesiochronous, and

Asynchronous

In a synchronous network, all the clocks are traceable

to one Primary Reference Clock (PRC).


Limitations of PDH Network

Inability to identify individual channels in a higher

order bit stream.

Insufficient capacity for network management;

Most PDH network management is proprietary.

There’s no standardized definition of PDH bit rates

greater than 140 Mbit/s.

There are different hierarchies in use around the

world. Specialized interface

equipment is required to interwork the two

hierarchies.


SDH Advantages

An optical mid-span meet between operators.

it’s synchronous.

it allows single- stage multiplexing and

demultiplexing.


Basic SDH Signal

Carry many different services in its Virtual container

(VC)

It is bandwidth-flexible. Can carry high-speed packet-

switched services like ATM.

SDH still permits transport and networking at the 2

Mbit/s, 34 Mbit/s, and 140 Mbit/s levels,

accommodating the existing digital hierarchy signals.


SDH Frame Structure


Logic composition of SDH equipment


Physical topology of an SDH transmission network


SDH Network

Survivability

(Protection Schemes)


Linear Protection

1+1

1:1

N:1,N+1,1:N, 1+N


Protection in SDH Ring

SHR

USHR BSHR

2F 4F2F 4F

Path Prot.(SNCP)

Path Prot.(SNCP)Path Prot.(SNCP)

Line Switched Prot.(MSSPRING)


FEATURES OF USHR

This scheme offers less information regarding

operating system.

In normal condition the traffic flows in clockwise

directions in one fiber.

In failure condition the traffic in counter clockwise

directions path is used.

The USHR mechanism itself does not remain aware

that which fiber is carrying traffic.


FEATURE OF BSHR:

The scheme requires an APS protocol to make it

operative.

The traffic flows from node 1 to node 3 in clockwise

direction along links 1p and 2p.

But in return path the traffic flows from node 3 to

node 1 in counter clockwise direction along links 7p

and 8p

No tie up of any primary channel bandwidth in the

other half of the ring


Concept of Speech in SDH Ring

A – in Bio Directional Self Healing Ring

RX TX

TX RX

TX RX

RX TX

Node 1

Node 2

Node 3

Node 4

RX TX

TX RX

TX RX

RX TX

1p

2p

3p

4p

5p

6p7p

8p


Node A

Circuit Q

Node B Node C

Node F Node E Node D

Working

Protection

Circuit Transporting Service

Normal Traffic In MS-Spring Node a

Node b Node c

Node dNode e

Node f

working

protection

Ckt transporting service

Normal state


`

Node A

Circuit Q

Node B Node C

Node F Node E Node D

Working

Protection

Circuit Transporting Service

Protected Traffic In MS-Spring

workingprotection

Ckt transporting service

Node a Node b Node c

Node dNode e

Node f

Failed state


MS shared protection rings

MS shared protection rings scheme is supported

by only BSHR

.The ring protocol is essential for both two fiber

ring or four Fiber ring.

In BSNL only two fiber rings are deployed.


CPE( Customer Premises Equipment)

Demand for optical connectivity at various SDH bit

rates like 2Mbps, 34 Mbps/ DS3 and STM1 level.

Demand for Ethernet connectivity at 10/ 100 Base T

Ethernet Trib. & 100 Base FX Ethernet trib with

facilities of inbuilt aggregation.

There will be an option of Ethernet Adapter to

convert Ethernet in desired bit rates.


CPE( Customer Premises Equipment)

For CPE, Remote monitoring through EMS on DCC

channel through VC12 in STM-1.

CPE terminals are having capabilities of Next

Generation SDH. (UPS for long duration required)

The VCG capabilities on VC12 and VC3 level can be

carried out in these equipments on VCAT principles

chapter02.sdh overview protection schemes & cpe

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