Re: Exit-Graceful Restart Condition

Padma Pillay-Esnault <ppe@CISCO.COM> Wed, 25 May 2005 15:02 UTC

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From: Padma Pillay-Esnault <ppe@CISCO.COM>
Subject: Re: Exit-Graceful Restart Condition
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sujay wrote:

>Hi All,
>Considering RFC3623, Graceful Restart for OSPF V2 I have a problem;
>  (network)---- DUT ---- RTA
>(All in the same area)
>Assume DUT undergoes a Graceful-Restart, it sends out grace LSA's to
>RTA and other routers in the 'network'
>At the instant RTA recvs the Grace-LSA it also goes down.
>Is there a way in the RFC 3623 specified as to how DUT could 
>Detect this topology change and Exit GR *before* grace period expiry??
I do not think the RFC covers this case. You are in a double failure 

I can think of a simple solution. When DUT reacquires its router-lsa. It 
can determine its previous
neighbors. It can then decide that if within DeadRouterInterval that 
neighbor did not  respond
to hellos to abort GR. This would be equivalent to the normal situation 
when a router goes down and its
neigbors takes DeadInterval to bring down their adjacency


>For other routers in the network RTA is still reachable and traffic 
>Will be eventually dropped.
>Kindly correct me,