Subject: [PWE3] some question about the PW redundancy

From: [email-masked]
Date: Thu, 27 Aug 2009 17:17:54 +0800

Hi，Muley:

You described the scenario below in the draft about the PW redundancy, and 
discussed the scheme to protect  AC or PE failures.

But what if the working PW failured? 

For example, assumed that AC1/PW4/AC4 is active now. Which PW(PW1/PW2/PW3) 
should be actived to transport the services if the linkd of PW4 is broken?
How to select? 

        |<-------------- Emulated Service ---------------->|
         |                                                  |
         |          |<------- Pseudo Wire ------>|          |
         |          |                            |          |
         |          |    |<-- PSN Tunnels-->|    |          |
         |          V    V                  V    V          |
         V    AC1    +----+                  +----+     AC3   V
   +-----+    |     |....|.......PW1........|....|     |    +-----+
   |     |----------| PE1|......   .........| PE3|----------|     |
   | CE1 |          +----+      \ /  PW3    +----+          | CE2 |
   |     |          +----+       X          +----+          |     |
   |     |          |    |....../ \..PW4....|    |          |     |
   |     |----------| PE2|                  | PE4|--------- |     |
   +-----+    |     |....|.....PW2..........|....|     |    +-----+
              AC2    +----+                  +----+    AC4

Best regards

Fei

:)