Re: Exit-Graceful Restart Condition

[Padma Pillay-Esnault <[e-mail]>]

Kishore Rao wrote:

>----- 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.
>  
>
It is not clear to me. Do you mean that RTB has the same neighbors as 
DUT and is on the same network link ?

Padma

>This would be faster than using the reacquired Router and Network LSAs to
>determine the neighbors, isnt it ?
>
>Kishore
>
>
>  
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>>    
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>>>Padma.
>>>
>>>      
>>>
>>>>For other routers in the network RTA is still reachable and traffic
>>>>Will be eventually dropped.
>>>>
>>>>Kindly correct me,
>>>>
>>>>Regds,
>>>>Ashok/Sujay
>>>>
>>>>
>>>>
>>>>        
>>>>
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