Subject: fast-reroute scenario

From: "Doug Degan" <[email-masked]>
Date: Thu, 8 Aug 2002 17:14:15 +0300

hi. 
Id like to get clarification about the regular FRR scenario:

[I]---[PLR]----[T1]---...-[Tn]--[MP]--------[E]
          \                           /
           \------------------------/
              BYPASS/DETOUR

Assume one of the links inside the segment PLR-T1...-Tn-MP fails. What are the messages that should be sent upstream and downstream? If PATH-TEAR is sent downstream, how does one distinguish between this PATH-TEAR and LSP shutdown originated by the ingress (user)?  In other case, assume Ti sends RESV-ERR downstream, but how does MP know to stop the proparation of this message? Also, in this case MP should know whether RESV-ERR was originated by T1-...-Tn or from outside the "protected section". 
 
The same argument applies for the upstream with RESV-TEAR/PATH-ERR.