Re: DR election

[Acee Lindem <[e-mail]>]

All,

This has been discussed before on this list and you could search
the archives to get all the gritty details. In summary:

   - The protocol attempts to avoid BDR/DR churn and the BDR/DR election
      gives the current BDR/DR precedence. The reason is obvious - you 
want to
     avoid the network overhead/convergence delay of bringing up
     adjacencies with the new BDR/DR as well as  the 
overhead/convergence delay
     of flooding and recalculating the intra-area route table with a new 
DR's
     network-LSA.
   - While it is not part of the protocol specification, an 
implementation could
      force a BDR/DR election by ignoring the fact that there is a 
BDR/DR and
     asserting themselves as BDR/DR. They would cause a NeighborChange
     event (Section 9.2, RFC 2328) causing RFC 2328 compliant 
implementations
     to perform a BDR/DR election.

Thanks,
Acee

Naresh Paliwal wrote:

>Erblich,
>
>I didn't get your reply, can u please give the references of the idea.
>
>I mean to ask, is it possible to enforce DR/BDR-election without
>changing configuration of existing DR/BDR?
>
>Regards
>-Naresh
>
>
>-----Original Message-----
>From: Mailing List [mailto:[e-mail]] On Behalf Of
>Erblichs
>Sent: Monday, May 02, 2005 10:07 PM
>To: [e-mail]
>Subject: Re: DR election
>
>Yes and no,
>
>If a router "really wants to be the DR", the protocol does
>allow this through a back door. The router must act like
>it was already also elected as the DR. This can happen in
>what was a split area. By coming up later, the later router
>SHOULD know the other's priority and router-id. It can then
>boost its broadcasted priority and/or its router-id to gurantee
>re-election.
>
>Mitchell Erblich
>----------------------
>
>
>"Krishnan, Vijay G." wrote:
>  
>
>>The first router does not become the DR immediately. It waits for its
>>configurable "wait timer" to expire, before electing the DR. Others
>>    
>>
>routers
>  
>
>>could come up during this time. Once the DR is elected, addition of
>>    
>>
>new
>  
>
>>routers would not change the DR. This will reduce the instability due
>>    
>>
>to the
>  
>
>>DR changes.
>>
>>regards
>>Vijay
>>
>>-----Original Message-----
>>From: Mailing List [mailto:[e-mail]]On Behalf Of Ilan
>>Bercovich
>>Sent: Monday, May 02, 2005 11:51 AM
>>To: [e-mail]
>>Subject: DR election
>>
>>Hello
>>If all routers accept the DR regardless of their Router Priority,
>>It means that actually the first active router on the LAN is the DR.
>>Isn't this makes the Router Priority parameter somewhat irrelevant?
>>(In RSTP for instance, when priority is changed - network is
>>re-calculated).
>>Ilan
>>    
>>
>
>  
>