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

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

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

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

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.

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

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

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

Additional Slides - 1:1 Node A Node Z Node A Node Z W 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