From: Jonathan Hays (nomad@gfoyle.org)
Date: Fri Dec 19 2003 - 15:37:54 GMT-3
Brian,
The little light bulb illuminated in my brain when I read your post.
Back in the dusty, musty corners of my memory banks (cough cough!) I was
aware that the area could be represented in ways other than a simple
decimal format, but the many practice hours of typing "net x.y.z.0
0.0.0.255 area 0" made me forget that alternative. ;-) I think you are
right on the money (as usual).
Many thanks for the response!
Jonathan
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Brian McGahan
Sent: Friday, December 19, 2003 11:23 AM
To: 'Marko Berend'; ccielab@groupstudy.com; nomad@gfoyle.org
Subject: RE: OSPF ID of 0.0.0.0
Jonathan,
The question is probably asking you to put the routers in OSPF
area
0. Typically you see the OSPF area number in normal decimal format,
however
it can use the dotted decimal format like an IPv4 address:
R1--12.0.0.0/8--R2
R1:
router ospf 1
network 12.0.0.1 0.0.0.0 area 0.0.1.255
R2:
router ospf 1
network 12.0.0.2 0.0.0.0 area 511
R2#show ip ospf nei
Neighbor ID Pri State Dead Time Address
Interface
12.0.0.1 1 FULL/DR 00:00:33 12.0.0.1
Ethernet0/0
Although the above area IDs are denoted differently, they are
both
the same binary number (111111111).
Also you are right about the BDR. There is no point having a
DR/DBR
on a non-broadcast segment that does not have direct layer 2
connectivity to
all endpoints of the NBMA network.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
Direct: 708-362-1418 (Outside the US and Canada)
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Marko Berend
> Sent: Friday, December 19, 2003 8:10 AM
> To: ccielab@groupstudy.com
> Subject: RE: OSPF ID of 0.0.0.0
>
> Hi
>
> I tried and my routers also ignore router-id 0.0.0.0
> But you can make the hub a DR and one of the spokes BDR by modifying
> priority since it is the first tie breaker (default priority is 1).
> Hub -> priority 2
> Spoke 1 -> pri 1
> Spoke 2 -> pri 0
>
> MB
>
> -----Original Message-----
> From: Jonathan Hays [mailto:nomad@gfoyle.org]
> Sent: 19. prosinac 2003 14:49
> To: ccielab@groupstudy.com
> Subject: OSPF ID of 0.0.0.0
>
>
> I recently saw a practice lab scenario with 3 OSPF area 0 routers
> connected via hub and spoke frame-relay (no subinterfaces). The
> requirement asked that the DR and BDR have an "ID of 0.0.0.0" which
> puzzled me. Unfortunately the solution was missing so I am asking for
> some help on figuring this one out.
>
> First, it seems to me that in a 3-router hub-and-spoke frame-relay
that
> a BDR is not possible, since neither of the spokes can function as a
> DR/BDR. Normally you just configure "ip ospf priority 0" on the spokes
> and the FR hub router becomes your DR. Maybe the requirement for a BDR
> was a typo? Or maybe the DR was required and the BDR was optional?
(But
> it does say DR *and* BDR.)
>
> Second, I thought of configuring the OSPF router ID of the F-R hub
with
> 0.0.0.0 (if indeed the router ID is the "ID" they were referring to)
but
> I tried it and OSPF does not like that. It just ignores the "router-id
> 0.0.0.0" config and uses the highest loopback. Are they referring to
> some other ID? LSA ID?
>
> Lastly, although there were no constraints against changing network
> type, since the question specifies DR/BDR then you cannot use OSPF
> point-to-point or point-to-multipoint since you have to have a DR (and
> maybe a BDR, too).
>
> Any ideas on this one?
>
> Thanks in advance,
>
> Jonathan
>
>
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