ota000006 sdh networking and protection issue 1.20

7/29/2019 OTA000006 SDH Networking and Protection ISSUE 1.20

1/59

www.huawei.com

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved.

SDH Networking and

Protection


2/59

Copyright 2006 Huawei Technologies Co., Ltd. All rights reserved. Page1

Objectives

Upon completion of this course, you will be able to:

Describe the common SDH network topology and features

Explain the protection mechanism


3/59


Contents

1. SDH Network Topologies

2. Survivable networks and their protection mechanisms


4/59


Contents


1.1 Optical networking introduction

1.2 Classification of topologies

1.3 Sub-networks


5/59


Optical Networking Introduction

An SDH network consists of Network Elements (NE)

interconnected with optical fiber.

The geometrical layout of the NEs and optical transmission

lines is called the network topology.

The efficiency, reliability and the cost performance of a

network highly depend on its topology.


6/59


Classification of Topologies

Chain

Star

Tree

Ring

Mesh


7/59


Classification of Topologies (Cont.)

Chain network is used when the networks nodes are arranged

in a long line.

e. g. along railway lines, highways, power supply lines, etc.

NE A NE B NE C NE D

Chain network (Point-to-point or point-to-multi-point network)

In a chain network, all nodes are connected one after another

on a line with both ends open.


8/59



Star network is mainly used in access networks or rural

telephone networks in which nodes are scattered here and

there and the traffics are not important.

Star network

In a star network there is a central node to which the other

nodes are directly connected. There are no direct links

between other nodes.

NE A

NE B

NE C NE D

NE E


9/59


Tree network is mostly used for broadcasted services like

CATV.


Tree network

A tree network can be considered as a combination of the

chain and star topologies.

NE A

NE B

NE CNE D

NE E


10/59


Ring network is widely used in SDH networking due to its high

survivability.


Ring network

Ring network is such a structure in which all nodes are

connected one after another to form a circle.NE A

NE B

NE C NE D

NE E


11/59


Mesh network is suitable for the regions with large amount of

traffic and for high hierarchy communication networks.


Mesh network

Mesh network is such a structure in which many nodes are

interconnected together via direct links.NE A

NE B

NE C NE D

NE E


12/59


Other possible combination networks



13/59


A sub-network functions as a container. It can include NEs,

links and even lower level sub-networks.

Sub-network

Sub-network

In backbone networks or large region networks, there are a

large number of NEs and links. In order to simplify the network

management, a large network can be divided into several sub-

networks according to the administrative regions.


14/59


Sub-network (Cont.)

Sub-network A

Sub-network B Sub-network C

Sub-network D

Subnet


15/59


Contents




16/59


Contents


2.1 Survivable networks introduction

2.2 Types of protection


17/59


Survivable Networks Introduction

Causes of network failures

Accidents: Cable/fiber cuts

Human errors: Incorrect maintenance, installation,

Environmental hazards: Floods, fire,

Sabotages: Physical, electronic,

Operational disruptions: Schedule upgrade, maintenance,

power outage, Hardware/software failures: Line unit failure, faulty laser,

software crash


18/59


Survivable Networks Introduction

(Cont.)

Survivable networks can restore traffic in the event of a failure

Requirements for survivability of network includes

Robust equipment (Strong cross-connect capability, intelligent nodes)

Security (Physical, electronic) Design networks with enough resource

Redundant routes as standby routes

Fast failure detection and fast traffic rerouting to redundant routes

No human intervention


19/59


Types of Protection

Line

Ring

Node

1+1 linear MS

M:N linear MS

Path protectionPP2-fiber unidirectional Path Protection Ring

2-fiber bidirectional Path Protection Ring

4-fiber bidirectional MSP Ring (4f-MS SPRing)

Multiplex section protection (MSP)

2-fiber bidirectional MSP Ring (2f-MS SPRing)

2-fiber unidirectional MSP Ring (2f-MS SPRing)

Sub-network connection protection (SNCP)


20/59


Line Protection

Working Channels

Protection Channels

NE A NE B NE C NE D

Use in point-to-point or chain networks

Switch is within two interconnected nodes


21/59


Linear 1+1 MS

Traffic source node sends the traffic on both working and protection

channels (Concurrent sending).

Traffic sink node receives the traffic from working channel(Selective

receiving).

When the working channel fails, traffic sink node switches to receivethe traffic from protection channel

NE A NE B


22/59


Linear 1+1 MS (Cont.)

Switching Modes

Single-ended (Unidirectional)

Dual-ended (Bidirectional)

Restoration Modes

Revertive (WTR Default: 600 sec)

Non-revertive

Automatic Protection Switch (APS) protocol is not required

when Single-ended and Non-revertive are selected.


23/59


Linear M:N MS

Protection Channel

Working Channel 1

Working Channel 2

Working Channel N

NE A NE B

Extra trafficNormal traffic

SwitchingSwitching Switching Switching

M Protection channels N Working channels


24/59


Linear M:N MS (Cont.)

Switching mode:

Bidirectional switching

Restoration mode:

Revertible mode


25/59


Line Protection

Line protection types Linear 1+1 MS

Linear M:N (M=1)

Protection switch criteria:

Signal Fail (SF): R_LOS, R_LOF, MS_AIS, B2_EXC.

Signal Degrade (SD): B2_SD.

Externally initiated protection switching command

Network Capacity:

1+1 linear MS: 1 x STM-N.

1:N linear MS without extra traffic: N x STM-N.

1:N linear MSP system with extra traffic: (1+N) x STM-N.


26/59


Questions

Which linear protection type switches the fastest?

Which type can carry extra traffic?


27/59


Ring Protection

Ring protection types:

Path protection (PP)

Multiplex section protection (MSP)

Traffic directions:

Unidirectional (PP Diversely routed, MSP Dedicated)

Bidirectional (PP Uniformly routed, MSP Shared)

Number of fiber:

2 fiber

4 fiber


28/59


Two-fiber Multiplex Section Shared

Protection Ring (2f-MS SPRing)

Fiber connection and slots

requirements:

2 fibers

Line boards must be inserted

in dual slots

Left line boardW

Right line board E

A

C

B

OUT

IN


29/59


S1S2

2f-MS SPRing (Cont.)

NE B

NE C

NE D

NE A

2f-MSSPRing

STM-16

P1

Protection channel (P): VC4 #9 ~ VC4 #16

P2

Working channel (S): VC4 #1 ~ VC4 #8


30/59



Exploded view of one fiber for STM-16 in 2f-MSSPRing

VC-4 #1VC-4 #2

VC-4 #3VC-4 #4VC-4 #5VC-4 #6VC-4 #7VC-4 #8VC-4 #9VC-4 #10

VC-4 #11VC-4 #12VC-4 #13VC-4 #14VC-4 #15VC-4 #16

Workingchannels (S)

Protection

channels (P)

Fiber

Section

overheads


31/59



Normal traffic flow between NE A & NE C

NE B

NE C

NE D

NE A

2f-MS SPRing

STM-16

S1

S2


32/59



Switched traffic flow between NE A & NE C

NE C

NE D

NE A

2f-MS SPRing

STM-16NE B

S1

P1

S2

P2

P2

Bridge &

Switch

Pass-through


33/59



When fiber is repaired, traffic switches back to working channels

after WTR time

NE B

NE C

NE D

NE A

2f-MS SPRing

STM-16

S1

S2


34/59



Protection switching trigger conditions: APS

Signal Failure (SF): R_LOS, R_LOF, MS_AIS, B2_EXC (Default)

Signal Degrade (SD): B2_SD (Optional)

Externally initiated protection switching command

Forced switch

Manual switch

Exercise switch

Protection switching restoration:

APS

Clearing of SF: R_LOS, R_LOF, MS_AIS, B2_EXC

Clearing of SD: B2_SD WTR (Wait to Restore): 10 minutes (5-12 minutes provisionable)

External commands

Clearing of Forced switch

Clearing of Manual switch


35/59



APS controller:

Processes APS protocol, which is carried in the K1, K2 bytes.

Transition of APS controller status

P

WTR

WTR P

I

I

I I

P

S

S P

I = Idle

P = Pass-through

S = Switching

WTR = Wait to Restore


36/59



Features of 2f-MSSPRing: Advantages:

Time slots can be reused

High network capacity: x M x STM-N

M is the number of nodes on the ring, STM-N is the STM level

Disadvantages:

Mechanism is complicated

Maximum number of nodes on one ring is limited to 16

Application:

Mainly for STM-4 and STM-16 or above systems

Scattered traffic distribution


37/59


Four-fiber Multiplex Section Shared

Protection Ring (4f-MS SPRing)

Structure:

4 fibers

Working channels (fibers) S1, S2, carry normal traffic

Protection channels (fibers) P1, P2, protect normal traffic

A

DC

EF

B

S1

S2

P1

P2


38/59



Traffic flow when network is normal:

Working channels = S1, S2

Protection channels = P1, P2

A

DC

EF

B

A DD A

A DD A

S1

S2

P1

P2


39/59



Traffic flow after only the working channel (s) is (are)

broken :

Span switching

A

DC

EF

B

S1

S2

P1

P2

A DD A

A DD A


40/59



Traffic flow after the working and protection channels are

broken:

Ring switching

A

DC

EF

B

S1

S2

P1

P2

A DD A

A DD A


41/59



Protection switching trigger conditions:

Automatic protection switching: Ring or Span

SF (Signal Failure): R_LOS, R_LOF, MS_AIS, B2_EXC

SD (Signal Degrade): B2_SD

External initiated protection switching: Ring or Span

Forced switch

Manual switch

Exercise switch


42/59



Protection switching restoration: Automatic protection switching: Ring or Span

Clear of SF (Signal Failure): R_LOS, R_LOF, MS_AIS, B2_EXC

Clear of SD (Signal Degrade): B2_SD

WTR (Wait to Restore): 10 minutes (5-12 minutes provisionable)

External command: Ring or Span

Clear of Forced switch

Clear of Manual switch

APS controller status:

Idle

Switching

Pass-through

WTR


43/59



Features of 4f_MSSPRing: Advantages:

Time slots can be reused

High network capacity: M*STM-N

Disadvantages: Maximum number of nodes on one ring is limited to 16

Mechanism is complicated

Expensive

Application:

Mainly STM-16 or above system

Scattered traffic distribution

Backbone system


44/59


Summary

MSP ring 2f_MSSPRing 4f_MSSPRing

Similarity

APS protocol necessary

Nodes number on MSP ring 16

SCC unit configures MSP protocol

Dual slots

Bidirectional and dispersed traffics

Difference

M*STM-N/2 capacity

(without extra traffic)

M*STM-N capacity

(without extra traffic)

Unique span switch

K1 & K2 bytes are in the protection fiber


45/59


Traffic transmit and

receive conditions in

normal situation.A

B

C

D

in

out

out

out

out

out

out

out

in

in

in

in

in

in

in

PP Ring

2M

2M

Concurrent sending

Selective receiving

out

Two-fiber Unidirectional Path Protection

Ring (Diversely Routed PP Ring)


46/59


Diversely routed pp ring



fiber failure situation.A

B

C

D

in

out

out

out

out

out

out

out

in

in

in

in

in

in

in

PP Ring

2M

2M

Concurrent sending

Selective receiving

Switching

out


47/59


Diversely routed pp ring

Protection switching trigger conditions

TU_AIS, TU_LOP, BIP_EXC

Features:

Every path (2M) switches independently.

Restoration mode is revertive.


48/59


Questions

Can the services

between stations

A and E be

protected?

A

B

C

D

in

out

out

out

out

out

out

out

in

in

in

in

in

in

in

PP

2M

2M

STM-N

Concurrent sending

Will the services be selectively

received here?

out

E


49/59


Node protection

Node protection type: Subnetwork connection protection (SNCP)

Protection features:

Traffic transmit end sends concurrently, receive end receives selectively

2 fiber unidirectional traffic (Diversely routed)

1 + 1 single-ended protection

Protection switching criteria:

Signal fail (SF)

Signal degrade (SD)

Externally initiated command


50/59


Subnetwork connection protection

(SNCP)

SNC

Starting

Node

SNC

Termination

Node

Protection

SNC

Working

SNC

Sub-Network 1

Sub-Network 2NE A NE E

Selector

Traffic out Traffic in Traffic out Traffic in

Normal condition Failure in working channel

Working channel

Protection channel

BridgeSwitch SwitchBridge


51/59


SNCP (cont.)



normal situation.A

B

C

D

in

out

out

out

out

out

out

out

in

in

in

in

in

in

in

SNCP Ring

2M

2M

STM-N

Sub-Network 1Sub-Network 2

Concurrent sending

Selective receiving

out


52/59


SNCP (cont.)


receive conditions

in fiber failure

situation.

A

B

C

D

in

out

out

out

out

out

out

out

in

in

in

in

in

in

in

SNCP Ring

2M

2M

STM-N

Sub-Network 1

Concurrent sending

Selective receiving

Switching

out


53/59


SNCP (cont.)

Protection switching trigger conditions :

Default

AU_AIS, AU_LOP, TU_AIS, TU_LOP, HP_LOM, HP_UNEQ

B3_EXC, Unplug the line card

Optional

HP_TIM, HP_SLM, B3_SD


54/59


SNCP (cont.)

Protection Restoration:

Wait to restore time 10 minutes (5-12 minutes provisionable)

10 min utes later

A

B

C

D

switching

S1

P1

A

B

C

D

S1

P1


55/59


Questions

What is the difference between unidirectional (diverse) andbidirectional (uniform) traffics?

What is the difference between SNCP and MSP protection

schemes? Which type of network protection can carry extra traffic?


56/59


Summary

A survivable network is capable of restoring services withina very short time and without any human intervention in the

event of a failure.

Linear protection networks can be classified into 1+1 linearMS and 1:N linear MS.

Ring protection networks can be classified into Path

Protection (PP) ring, Multiplex Section Protection (MSP) ring.

Sub-Network Protection (SNCP) is used for node protection.


57/59


Item 2f_MSSPRing SNCP

APS protocol Necessary Unnecessary

Typical services Bidirectional and distributedUnidirectional and

centralized

Switch level (objective) MS SNC services

Suitable networking Only ring Any topology

Switching implementing boards LU, XC LU, XC

Switch time 50ms 50ms

Network Capacity (without extra

service)K*STM-N/2 STM-N

Extra traffic Supported Not supported

Summary (cont.)


58/59


Summary (cont.)

EquipmentLinear

MS

2f-MS

SPRing

4f-MS

SPRingPP SNCP

Metro 100 Support No No No Support

Metro 200/500 Support No No Support Support

Metro 1000V2 Support Support No Support Support

Metro 1000V3/1050 Support Support No No Support

Metro 2050/3000 Support Support Support Support Support

Metro 5000, OSN

1500/2500/3500/7500/9500Support Support Support No Support


59/59

Thank youwww.huawei.com

ota000006 sdh networking and protection issue 1.20

Documents