RE: OSPF FR adjacency question posted 09/17/2006
- Subject: RE: OSPF FR adjacency question
- From: "Brian Dennis" <bdennis@xxxxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 17 Sep 2006 13:17:15 -0400
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- Thread-topic: OSPF FR adjacency question
Here is a post that I sent in the past regarding this issue.
Even though the routers are "adjacent" they won't become true neighbors
with each other. By adjusting the hello/dead timers you can make any
OSPF network type become adjacent but that doesn't mean they will become
functioning OSPF neighbors.
OSPF network types that use a DR (broadcast and non-broadcast) can
neighbor with each other and function properly. Likewise OSPF network
types (point-to-point and point-to-multipoint) that do not use a DR can
neighbor with each other and function properly. But if you mix DR types
with non-DR types they will not function properly. You should see in the
OSPF database "Adv Router is not-reachable" messages when you've mixed
DR and non-DR types.
Here is what will work:
Broadcast with Broadcast
Non-broadcast with Non-broadcast
Point-to-point with Point-to-point
Point-to-multipoint with Point-to-multipoint
Broadcast with Non-broadcast (adjust hello/dead timers)
Point-to-point with Point-to-multipoint (adjust hello/dead timers)
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
Internetwork Expert, Inc.
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
Sent: Sunday, September 17, 2006 9:28 AM
Subject: OSPF FR adjacency question
I'm sure this question comes up all the time, but i've had a quick look
through the archive and could find a previous posting.
I'd like your opinion on the following scenario (hub & spoke over FR,
- Hub has point-to-multipoint interface (in both ospf and FR and has FR
broadcast to spokes)
- Spokes have point-to-point interfaces (in both ospf and FR and has
interface-dlci to hub)
By default this configuration will not build an adjacency because of
different hello timers. Which of the following solutions (or others if
you have them) do you think is the "prefered" way to set up OSPF
adjancencies in this scenario?
1. Change hello time on both spokes to 30 secs.
2. Change hello time on hub to 10 secs.
3. Change the ospf network type on spokes to point-to-multipoint
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