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RE: OSPF FR adjacency question posted 09/17/2006
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Here is a post that I sent in the past regarding this issue. 

<quote>
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) 
</quote>

HTH,


Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@xxxxxxxxxxxxxxxxxxxxxx 
 
Internetwork Expert, Inc. 
http://www.InternetworkExpert.com 
Toll Free: 877-224-8987 
Direct: 775-745-6404 (Outside the US and Canada) 
 

-----Original Message-----
From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
Peter Cresswell
Sent: Sunday, September 17, 2006 9:28 AM
To: ccielab@xxxxxxxxxxxxxx
Subject: OSPF FR adjacency question

Hello all,
 
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,
single
subnet):
 
			Hub
		     /   \
		    /     \
		Spoke1   Spoke2

- 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


Thanks,

Peter

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