1. SD-Triggered Protection Switching in MPLS-TP draft-zhl-mpls-tp-sd-01
SD-Triggered Protection Switching in MPLS-TP draft-zhl-mpls-tp-sd-01.txt
IETF 76th meeting – Hiroshima, November 2009
H. Zhang, J. He, Huawei
H. Li, CMCC

2. Requirements In draft-ietf-mpls-tp-survive-fwk-02
Section Failure-Triggered Actions: “Survivability actions may be directly triggered by network failures……"failure" is used to represent both signal failure and signal degradation”
This document describes Signal Degrade (SD) detection and the consequent protection switching mechanism

3. Motivation
The SD condition used for protection switching mostly depends on LM (packet loss ratio) and DM (packet delay and delay variation)
LM need to measure the amount of the lost service packets
So the detection of SD must be based on service packets
In 1:1 and 1:n protection architecture
There is no normal traffic on working/protection transport entity, which makes the detection of SD impossible and causes switch flapping

4. Motivation Example for flapping
In fact, there are SD on both working and protection entities
But only the SD condition on entity that carries the normal traffic can be detected, which cause the flapping between working and protection entities
Node A
Node Z SD W P SD
Selector Bridge
Selective Selector W P
Selective Selector
Selector Bridge
Normal Traffic
Best Effort Traffic

5. SD-Triggered Protection Based on OAM
Detection of SD by Test
Test OAM packets can be used to simulate the characteristics of the normal traffic and replace the normal service
With the performance monitoring OAM packets (LM) the SD condition of the transport entity can be detected
Detection of SD by CC/CV
CC/CV OAM packets can be used instead of normal service in packet loss measurement
LM will count CC/CV packets and the loss measurement is based on CC/CV packets, which will be used as the input of SD condition
[Note]: The detection of SD by CC/CV is not recommended when the packet loss is caused by congestion.

6. SD-Triggered Protection Based on Broadcast Bridge
Example for Broadcast Bridge with priority of SD-W > SD-P
Protection switching not active: the normal traffic is sent only on the working transport entity
Protection switching is active: normal traffic is sent on both working and protection transport entities by closing the switch on Broadcast bridge
Node A
Node Z SD W P SD
Broadcast Bridge
Selective Selector W P
Selective Selector
Broadcast Bridge
Normal Traffic
Best Effort Traffic

7. Next Step
Feedback on the list
Move to working group draft?

8. Questions?

9. Additional Slides – Protection Component
Bridge
Selector
Permanent Bridge W P
Broadcast Bridge W P
Selector Bridge W P
Selective Selector W P

10. Additional Slides - 1+1 Node A Node Z 1+1 with Permanent Bridge W P
Selective Selector W P
Selective Selector
Permanent Bridge
1+1 with Permanent Bridge

11. Additional Slides - 1:1 Node A Node Z Node A Node ZW P
Selector Bridge
Selective Selector W P
Selective Selector
Selector Bridge
1:1 with Selector Bridge
Node A
Node Z W P
Broadcast Bridge
Selective Selector W P
Selective Selector
Broadcast Bridge
1:1 with Broadcast Bridge