From: John Smith (c00per_omers1@yahoo.com)
Date: Wed Nov 12 2003 - 12:39:54 GMT-3
To avoid ISDN routes appearing as /32 you require no peer neighbor cmd.
To avoid loopback interfaces use the "IP ospf network Point-to-Point" cmd
Michael Schwarz <flying_eskimo@hotmail.com> wrote:
HDLC was designed for links that used the same subnet for both ends of the link. PPP was designed so that it could be used in situations where both sides of the link were on completely different networks, therefore during the actual negotiation of the PPP protocol, PPP will install a host route to the remote device. If using the same subnet for both sides of the link you can of course safely turn this feature off.
Kind of like using HDLC with ip unnumbered on both sides. I think its the same general idea. Maybe a search on ppp negotiation will provide more useful results.
Has anyone tried using ip unnumbered on ISDN link (with ospf), does it
follow the same behavior, keeping up the ISDN link? That would be
interesting to know.
michael
----- Original Message -----
From: "Casey, Paul (6822)"
To:
Cc: "'ccie2be'"
Sent: Monday, November 10, 2003 11:45 PM
Subject: RE: peer neighbor route.,
I didnt think it had anything to do with OSPF but more related to PPP.
All why the /32 is keeping the line up is well documented on the Cisco
website...!!
If the ISDN link was HDLC I dont think the same problem would occur.
Anyone, any other explainations of this command..!!
What is peer neighbor route really for..!!
Kind regards.
Paul.
-----Original Message-----
From: ccie2be [SMTP:ccie2be@nyc.rr.com]
Sent: Monday, November 10, 2003 9:08 PM
To: Casey, Paul (6822); ccielab@groupstudy.com
Subject: Re: peer neighbor route.,
When redistribution into OSPF is taking place on one of the routers on one
end of the link and the ip subnet of the link is included under the ospf process, using this command stop the isdn link from flapping.
I don't remember all the details but the way I understand it is that without
this command, when the isdn link comes up (from interesting traffic for
example), ospf will install a new /32 route in the route table. When
the link goes down, ospf removes the route, But when the /32 route is removed
that means there's been a topology change. OSPF, being a routing protocol,
must, of course, notify all it's neighbors of the topology change and send
out a new LSA to do this. And, this new LSA has to, of course, reach the
other side of the isdn link so ospf brings up the link. Once the link is up
that /32 route is again installed in the route table only to go away again
after the link goes back down. And, so the cycle repeats.
To stop this cycle, the no peer neighbor command prevents the /32 route from
being installed in the route table in the first place.
I forget the roll that redistribution plays in this scenario, but I know that this is explained very well in the book, Troubleshooting IP Routing Protocols in the section on flapping isdn links (or using the ip ospf demand circuit command).
----- Original Message -----
From: "Casey, Paul (6822)"
To:
Sent: Monday, November 10, 2003 2:39 PM
Subject: peer neighbor route.,
Hello,
I am been looking this peer neighbor route command used under PPP.
Can someone explain to me what this command is actually for, Yes, I have read that you can remove the /32 host routes it installs from the far side of the link, used for ISDN ..by typing the no form of the command. but what is the purpose of this command when its turned on.
ex: Why would I want to use this command in the first place - or more to
the point what can I not do without it,..? What do I need /32 host routes for.
Anyone got an example. Cisco website is vague of this stuff. or maybe its just the links I can find are vague.
Any help appreciated.
Kind regards.
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