SD-Triggered Protection Switching in MPLS-TP draft-zhl-mpls-tp-sd-01.txt

1. SD-Triggered Protection Switching in MPLS-TPdraft-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 4.1.2. 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 Selective Selector Selector Bridge 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 Selective Selector Broadcast Bridge 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. Permanent Bridge W Broadcast Bridge W P P Selective Selector W Selector Bridge W P P Additional Slides – Protection Component • Bridge • Selector

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

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