Re: Waiting State Question

[John Smith <[e-mail]>]

Hi Mukul,

Extending the same logic cant we say that an if an interface comes out of waiting state
on recieving a Hello from a BDR then it may elect itself as the DR. Okay .. I think i
understand this.

A network will *always* have a DR even if its this single router. So we are sure that if
we recieve a HELLO from the BDR then it will *always* list the DR. SO we now know the
identity of the DR and the BDR.

But, if i recieve a HELLO from the DR cant i look at the BDR field and know that there
exists a BDR and declare that same router as the BDR? OR is the assumption that unless i
hear from that BDR i cannot confirm that its still up. Is this it?

Pretty confused,
John

Mukul Said :

My guess is that if an interface comes out of the waiting state on receiving a
Hello from DR (without having received a Hello from BDR), it may elect itself
as BDR. This way many routers may elect themselves as BDR. Now all these BDR
claimants (except one) will ultimately take their claims to BDRship back but in
the process each router on the LAN may have to do several DR elections.

Here is a paper we wrote recently that may shed further light on this:
http://cs.uwm.edu/~mukul/ospflan.pdf

Thanks,
Mukul




		
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