Re: Waiting State Question

[Mukul Goyal <[e-mail]>]

OK. So we agree that an interface comes out of waiting state on receiving a
Hello from DR IF that hello does not list any BDR. OTHERWISE an interface does
not come out of waiting state on receiving a Hello from DR.


Quoting Kishore Rao <[e-mail]>:

> Not NeighborChange but Backupseen
>
> "If the neighbor is both declaring itself to be Designated
>             Router (Hello Packet's Designated Router field = Neighbor IP
>             address) and the Backup Designated Router field in the
>             packet is equal to 0.0.0.0 and the receiving interface is in
>             state Waiting, the receiving interface's state machine is
>             scheduled with the event BackupSeen."
>
> > I think the NeighborChange events are ignored while an interface is in
> waiting
> > state.
> >
> > Thanks,
> > Mukul
> >
> >
> > Quoting Kishore Rao <[e-mail]>:
> >
> > > The question was not about how DR or BDRs are elected. John's question
> was
> > > if the router should exit Wait Timer (and run DR election) on receving
> Hello
> > > from a router declaring itself as DR. Well, from section 10.5 it should.
> > >
> > > Kishore
> > >
> > >
> > > > 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
> > > >
> > > > Quoting John Smith <[e-mail]>:
> > > >
> > > > > Hi,
> > > > >
> > > > > When a router comes up it starts the Wait Timer before it elects the
> > > DR/BDR.
> > > > > It either
> > > > > waits for the Wait Timer to expire or it waits for a router
> declaring
> > > itself
> > > > > as the BDR
> > > > > before it decides that it needs to get out of the 'Waiting' state
> (it
> > > does
> > > > > this by
> > > > > generating the Backupseen event).
> > > > >
> > > > > My question is why does it wait only for the BDR? Why not the DR? It
> can
> > > when
> > > > > it recieves
> > > > > a HELLO from the DR know that their exists a DR and a BDR. Why not
> then
> > > get
> > > > > out of the
> > > > > 'Waiting' state?
> > > > >
> > > > > Thanks,
> > > > > John
> > > > >
> > > > > Send instant messages to your online friends
> > > http://uk.messenger.yahoo.com
> > > > >
> > >
>