Survival of Sdh Network

Survivability Of SDH

Network

By: TX-I Faculty ALTTC, Ghaziabad

TX- 1 Faculty ALTTC, Ghaziabad

Concept of a Speech in Point to Point link

RXTXTXRX


SDH Rings1 SDH is normally configured in a ring architect.

2 This is done to create loop diversity for uninterrupted service protection purposes in case of link failures.

3.The SDH rings are commonly called self healing rings, Because traffic flowing in a certain path can be switched automatically to an alternate path.

4.Self healing rings works on two different type of chemistry.A- Unidirectional Self healing rings. B- Bi-directional Self healing rings .

5. The concept of traffic in both type ring is different.


Features of SDH RingsThere can be either two or four fibers running between the nodes on a ring.

2. The operating signals can travel either clockwise or counter clock only (USHR).

3. The operating signals can travel in both directions aroundThe ring (BSHR).

4.Protection switching can be performed either via a line switchedOr a path switching scheme.

5.In BSNL only two fiber ring mechanism is being adopted.


Concept of Speech in SDH Ring A in Uni Directional Self Healing Ring RX TXTX RX

TX RXRX TX

RX TXTX RX

TX RXRX TX

ADM AADM BADM CADM D


Features of USHR


Continued Features of USHR

The chemistry of USHR is less informative.

But it protect traffic positively.

It offers cost effective solution for low level of capacity network.


In USHR , two type of protection scheme are applicable1- Path protection2- line switched protection


USHR Path Protection Node ENode DNode CNode ANode B


Actually in our system path protection is not there Q. Why Ans. In our systems we are keeping on auto laser set and auto laser restart functions on always. So if one fiber is going to be faulty both ends lasers switched off and it simulate the condition of complete section faulty condition.


Concept of Line Switched Protection

In our systems actually line switch protections is available It satisfied three condition Traffic is always in Ring And traffic always in one direction Traffic is in ring of one fiber.


Concept of Line Switched Protection A in Uni Directional Self Healing Ring

RX TXTX RX

TX RXRX TX

RX TXTX RX

TX RXRX TX

ADM AADM BADM CADM D


Feature of BSHR The chemistry of BSHR is more informative.

The scheme requires a APS protocol to make operative.

The traffic flows from node 1 to node 3 in clockwise Direction along links 1p and 2 p.

But in return path the traffic flows in counter clockwiseFrom node 3 to node1 along links 7p and 8p.

Thus the information exchange between nodes 1and3 doesnot tie up any of the primary channel bandwidth in the otherHalf of the ring.


Concept of Speech in SDH Ring A in Bio Directional Self Healing Ring RX TXTX RX

TX RXRX TX

Node 1Node 2Node 3Node 4RX TXTX RX

TX RXRX TX

1p2p3p4p5p6p7p8p


Concept of BSHR Protection Mechanism

To understand the concept of BSHR it is very essential to understand the concept of traffic.

Traffic is Theoretically of two type Centralized Traffic Distributed Traffic

But practically traffic is having mixed concept


Concept of Centralized Traffic Pattern ( Without MS-spring)


Node ANode DNode BNode CTwo-fibre STM-16 ring 2 AU-4s 8 AU-4s 6 AU-4s 16 AU-4s total Spare between Nodes A & B andNodes A & D are at capacity

Centralized Traffic Pattern 8 AU-4s6 AU-4s2 AU-4sTwo fiber STM-16 ring


Since all the traffic is designated for node A, and the span Between Node A and node B is full. Traffic from node C routes through node D, Leaving the span between Node B And node C vacant.


Node ANode DNode BNode CTwo-fibre STM-16 ring 8 AU-4s 8 AU-4s 8 AU-4s 8 AU-4s32 AU-4s totalAll spare are at capacityPurely Distributed Traffic Pattern 8 AU- 4s8 AU-4s8 AU-4s


MS shared protection ringsMS 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.MS shared protection rings are characterized by dividing the total payload per multiplex section equally into workingand protection capacity.

For a two fiber STM_N ring, N/2 administrative unit Groups (AUGs) available for working and N/2 (AUGs) for protection.

The protection capacity is shared between multiple Multiplex sections


The sharing of protection capacity may allow a multiplex section shared protection ring to carry more traffic underNormal conditions than other ring types.

The sum of the tributaries that transverse a span cannot exceed the maximum capacity of the particular span.

In MS shared protection the service can be routed in either one of the two directions,the long way around the ring or the short way.

For normal working shortest path is preferable.

For failure condition ,the alternate path in used.


Node ACircuit Q Node B Node CNode F Node E Node D WorkingProtection Circuit Transporting ServiceNormal Traffic In MS-Spring Node aNode bNode cNode dNode eNode fworkingprotectionCkt transporting serviceNormal state


`Node ACircuit Q Node B Node CNode F Node E Node D WorkingProtection Circuit Transporting ServiceProtected Traffic In MS-Spring working

protectionCkt transporting service

Node aNode bNode cNode dNode eNode fFailed state


Procedure of loading MS-spring. Prepare physical map of ring of different nodes.

assign individual node ID to each node either in clockwise direction or in counter clockwise direction .

Zero node ID be offered to master node.

Maximum station may not be more than 16 excluding regenerator.


Procedure of loading MS-spring.


Translate physical map of STM 16 Ring in to soft copy Follow the screen instruction for further loading the rings.


Preparation of MS Spring Node Map Editor

Node ID Slot No. 1Slot No. 06011512023134245356467578689791081011911121012131113141214151315014


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Survival of Sdh Network