Re: Exit-Graceful Restart Condition

[Kishore Rao <[e-mail]>]

----- Original Message ----- 
From: "Acee Lindem" <[e-mail]>
To: <[e-mail]>
Sent: Wednesday, May 25, 2005 10:10 AM
Subject: Re: Exit-Graceful Restart Condition


> Padma Pillay-Esnault wrote:
>
> > sujay wrote:
> >
> >> Hi All,
> >>
> >> Considering RFC3623, Graceful Restart for OSPF V2 I have a problem;
> >>
> >> Ex:
> >>
> >>  (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
> > situation.
> >
> > 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
>
> I agree completely with Padma. One point, if RTA comes back up and
> originates a new router LSA
> then the DUT will detect the inconsistency (as specified in RFC 3623)
> with it's pre-restart LSA and
> terminate graceful restart.

Acee,

Will this work ?
In case there is another router RTB, scan the Hello from RTB for all
neighbors on the network and then make sure Hello from RTA has been received
within a Hello interval + 2 (say) . If not, exit GR.

This would be faster than using the reacquired Router and Network LSAs to
determine the neighbors, isnt it ?

Kishore


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