From: Gustavo Novais (gustavo.novais@novabase.pt)
Date: Wed Feb 01 2006 - 13:24:20 GMT-3
Hi,
In fact this is a bit of mislead between theory and practice.
If you try it out, you'll see that just configuring neighbors on hub
will work.
Regarding the ip priority 0, as I was remembered by GS some time ago, it
is not a requisite for this type of topology. Things will work if you
don't set it to 0. But probably they will not work the way you wish to.
Regarding of how will the spokes know where is the HUB (DR), if you
remember you configured neighbor x.x.x.x (which by default configures
this remote neighbor with priority 0) on the hub.
So, what will happen is that each hub will send unicast hellos and DBD's
(because of neighbor command) coming from a router (HUB). There is your
answer. They will engage in DR/BDR election, on the moment that spoke
receives that DBD, and reply to its source. If you configured spoke
with lower priority than hub, spoke will become BDR (or non-dr).
Hence in practice you do not need to configure neighbor on spoke
routers.
My 0.02$
Gustavo Novais
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Popgeorgiev Nikolay
Sent: quarta-feira, 1 de Fevereiro de 2006 15:50
To: ccielab@groupstudy.com
Subject: ospf misunderstanding
Dear all,
I have a small question about ospf, network types and frame-relay.
Here is a sample network:
two spokes, one hub. The requirement is to enable ospf between them and
to use non-broadcast network type on the interfaces.
This leads to a DR/BDR election, and according to me the DR should be on
the hub and there shouldn't be BDR.
Also I have to put "ip ospf priority 0" on my spoke routers' interfaces
right?
Cause the network doesn't allow multicasts I have to specify neighbors -
two from the DR and one on each spoke.
BUT in a solution from a work book I saw this sentence :
"The neighbor statements are required only on interfaces that are NOT
configured with ip ospf priority 0 (which means spokes don't need
neighbor command)"
SO how does the spokes find where to make their adjacency ?
thanks,
Nick
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