Chapter02.SDH Overview Protection Schemes & CPE

E2-E3 E&WS SDH Overview , Protection Schemes & CPE

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This is a presentation presentation for the E2-E3 EW&S Module for the Topic: SDH Overview , Protection Schemes Schemes & CPE

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Eligibility: Eligibility: Those who have got the Upgradation to from E2 to E3.

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This presentation is last updated on 15-32011.

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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 hierarchies.

required

to

interwork

the

two

SDH Advantages

An optical mid-span meet between operators. it’s synchronous.

it allows singledemultiplexing.

stage

multiplexing

and

Basic SDH Signal Carry many different services in its Virtual container  (VC) It is bandwidth-flexible. Can carry high-speed packetswitched 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 

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

2F

BSHR

4F

2F Path Prot. Path Prot. (SNCP) (SNCP)

 

4F 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

4p

Node 1

1p 8p

5p Node 4

TX RX RX TX

TX RX RX TX

7p

6p 3p

Node 2

2p RX TX TX RX

Node 3

Normal Traffic In MS-Spring  Node a  Node A Circuit Q

 Node  Node B

b

Node E  Node

e

 Node C

 Node c

 Node f 

 Node F

Working working Protection  protection

Ckt transporting service

Circuit Transporting Service

 Node D

 Node d

 Normal state

Protected Traffic In MS-Spring  Node C  Node Node A a Circuit Q

 Node B

 Node b

Node c

`

 Node f 

 Node F

Node E

working Working

 Node e

 protection Protection Ckt transporting service Circuit Transporting Service

 Node D

 Node d

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