Re: Waiting State Question

[Kishore Rao <[e-mail]>]

> What is b/n them is broken?

Comunication between them is broken.

>
> Combine areas and former entry/exit interfaces between
> the areas will result in two or more DRs announcements
> per pseudonode.
>
> This is taken care of in the Spec? Can anyone find the
> section? :-)

Section F: Multiple interfaces to the same network/subnet.

I could not find any other section other than this.

F:  says both the interface should be taken care of together so that there
are no
multiple DRs elected by the same router. In your case, DRs were elected by
two different routers,
which I think could happen only if they have no communication beween them ?

Kishore

>
> Mitchell Erblich
> -------------------------
>
> Kishore Rao wrote:
> >
> > > Second, "in the case where more than 1 router"
> > > is declaring itself as the DR, shouldn't enough
> > > time pass (1.5 to 2x) hello interval pass to identify
> > > this situation before exiting wait state and
> > > poss determine whether 2-ways are forming.  Yes,
> > > it could/should exit early, but on that first
> > > hello???
> >
> > A possible case of A & B declaring themselves as DR would be when comm.
b/n
> > them is broken; in which case shouldn't router C prefer to elect itself
as
> > BDR ASAP on receiving the hello from either A or B instead of waiting
for a
> > longer period of time without the possiblity of neither A or B being
elected
> > BDR during that time ?
> >
> > >
> > > Thus, this section of the spec covers the rare simple
> > > case where no BDR has yet been elected or is eligible
> > > to be elected.
> > >
> > > Mitchell Erblich
> > > -----------------
> > >
> > >
> > >
> > > Kishore Rao wrote:
> > > >
> > > > 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
> > > > > > > >
> > > > > >