Subject: Re: [PWE3] some question about the PW redundancy

From: "AISSAOUI Mustapha" <[email-masked]>
Date: Thu, 10 Sep 2009 17:15:51 -0500

Hi Fei,
I do not believe this question was answered.
 
The scenario below is for protecting against AC and PE failures. Thus, the redundant PWs terminate on two different remote PEs and the advertised 'active/standby' forwarding state in the PW status TLV reflects the forwarding state of the AC. 
 
It is assumed that protection against network failures uses other mechanisms such as LSP FRR or secondary backup.
 
Regards,
Mustapha.

________________________________

	From: [email-masked] [mailto:[email-masked]] On Behalf Of [email-masked]
	Sent: Thursday, August 27, 2009 5:18 AM
	To: MULEY Praveen
	Cc: [email-masked]
	Subject: [PWE3] some question about the PW redundancy

	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 
	
	:)