Re: [OSPF] OSPF GR query

Acee Lindem <acee@cisco.com> Fri, 15 September 2006 20:46 UTC

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Date: Fri, 15 Sep 2006 16:46:03 -0400
From: Acee Lindem <acee@cisco.com>
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To: Khan Amir-G20247 <amirkhan@motorola.com>
Subject: Re: [OSPF] OSPF GR query
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Hi Amir,
See answers inline.
Khan Amir-G20247 wrote:
> Hi 
>
> I have query related to Strict LSA Checking in OSPF Graceful Restart.
>
> Consider this scenario:
>
> - Two Routers R1 and R2, connected with a Broadcast network.
> - Where R1 is a DR and R2 as DR-other
> - Now R2 wants to perform GR and R1 agrees to be its Helper.
> - Now after restart R2 will try and form adjacency with R1.
> - Lets say that R1 and R2 had reached Exstart state. Now at this time
> another router R3 joins the network.
> - This router R3 will effect the contents of R1 LSDB. 
> - Now if Strict LSA Checking is enabled, R1 will quit from Helper mode.
> - After quiting R1 will recalculate DR/BDR and will reoriginate router
> LSA and network LSA. 
>
>
> Considering above scenario, my doubts are:
>
> - How will R2 come to know that its Helper has quit ?
>   
When it receives its pre-restart LSA from any neighbor in the area, it 
will recognize
that it should terminate graceful restart.

> - When will R2 exit GR ? 
>   
See above.
> - As the NBR state had reached to Exstart before R1 exited, will state
> be back to Down and   
>   the adjacency formation will start all over again, once R2 exits GR ? 
>   
No - there is no need to. R1 is the DR and should remain DR.

Thanks,
Acee





>
> Regards
> Aamir
>
>
>   

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