Subject: [OSPF] Re: Query on OSPF Summary LSA

From: Acee Lindem <[email-masked]>
Date: Thu, 23 Aug 2007 08:30:55 -0400

Hello Jishnu,

On Aug 23, 2007, at 7:02 AM, Jishnu Banerjee wrote:

> Hello,
> I have query related to OSPF Summary LSA update and subsequent SPF  
> calculation in-order to install the network (learnt through Summary  
> LSA) in route-table
>
> Case 1: Referring to the topology below, è
>
>                   R2
>                   |
>                   |
>          Area 0(121.121.121.0/24)
>                   |
>                   |
>                   R1---Area14(14.14.14.0/24)--R4
>
> Should R4 routing table contain the network 121.121.121.0/24 ?
Yes - unless Area 14 is a stub or NSSA area with summary  
advertisement suppressed.

>
>
> Case 2:  Referring to the topology below, è
>
>
>                   R2
>                   |
>                   |
>          Area 0(121.121.121.0/24)
>                   |
>                   |
>                   R1---Area14(14.14.14.0/24)--R4--Area45 
> (45.45.45.0/24)--R5
>
>
> a>     Should R4 (as per above topology its now an Alternate ABR)  
> routing table contain the network 121.121.121.0/24 ?
Yes. However, R5 will not. Note that RFC 3509 is a non-standard  
Informational RFC and I would discourage building networks dependent  
on its operation.
> b>     Should R1 (backbone ABR) routing table contain the network  
> 45.45.45.0/24 ?
Yes.

Hope this helps,
Acee
> Regards,
> Jishnu Banerjee

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