From: Pamela Forsyth (pforsyth@xxxxxxxxx)
Date: Wed Apr 04 2001 - 07:52:51 GMT-3
Guy,
You are not missing anything. This is correct behavior for OSPF over
NBMA for the ways you have configured it.
When OSPF sees "encap frame" on your serial interface it assumes
"non-broadcast" mode of operation. In this mode OSPF will not dynamically
seek out neighbors. However, if you put a "neighbor" statement in the
router, telling him, "hey, go out and find this guy, and when you do,
become neighbors with him," he will do that. Now that his neighbor
relationship is established, does it make sense that he should drop the
relationship if the neighbor statement is removed? Of course not. THe
"neighbor" statement is there so he can discover his neighbor, and has no
purpose after that. Now if you were to reboot the router . . . you'd have
to tell him again (put a new "neighbor" statement in).
By putting the "ip ospf network broadcast" statement on the frame-relay
interface, you are just telling the router, "please treat this frame-relay
cloud as though it were an ethernet -- go out and find your neighbors
yourself, because I'm not going to tell you who they are." This will
enable the hellos without the necessity of configuring neighbors explicly.
There are three other ways Cisco routers can be configured for OSPF over
NBMA. BSCN covers this pretty well (at least if you took my class ;-)).
Pamela
On Wed, 4 Apr 2001, Guy Farber wrote:
> Guys,
>
> I have a very simple FR network. One router functions at the FR switch and 2
> others have a pvc between them. When I run OSPF over the FR link without
> changing any OSPF interface parameters and using in-arp, hellos are not
> being sent from the routers. If I change the interface type to broadcast,
> they start exchanging hellos and finally build an adjacency. Now for the
> interesting part, if I put a neighbor statement on one of them they start
> exchanging hellos and become neighbors. If I remove the neighbor statement
> it stays the same.
>
> I'm using 2621 and 3640 with ver 12.1(4)
>
> What am I missing here?
>
> -------------------------------------------------
> Guy Farber
> Systems Engineer
>
> Tel: +972 (9) 970-0363
> Fax: +972 (9) 970-0019
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> Email: gfarber@cisco.com
>
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> ISRAEL
> -------------------------------------------------
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