Re: DR election

[Acee Lindem <acee at CISCO.COM>]

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:OSPF at PEACH.EASE.LSOFT.COM] On Behalf Of
> Erblichs
> Sent: Monday, May 02, 2005 10:07 PM
> To: OSPF at PEACH.EASE.LSOFT.COM
> 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:OSPF at PEACH.EASE.LSOFT.COM]On Behalf Of Ilan
> > Bercovich
> > Sent: Monday, May 02, 2005 11:51 AM
> > To: OSPF at PEACH.EASE.LSOFT.COM
> > 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
> >    
>
>