From: Jimmy Dotson (dotsonjl@xxxxxxx)
Date: Fri Jan 19 2001 - 12:00:55 GMT-3
Hello all. I'm new to the group. Been lurking for a while.
Shaun, I understand where you're coming from, but I've got a question. Isn't O
SPF on-demand only to keep the BRI quiet in stable environments? If you add a
route into the OSPF AS, then wouldn't the BRI link fire up to propagate the LS
change (or does on-demand only look at it's particular area)? This would happe
n when the primary link is up OR down. How is this an acceptable solution to O
NLY backing up a serial interface (I just fear I might loose this argument - wi
th one particular proctor I'm almost sure I would)?
Jimmy
>>> Shaun Nicholson <Shaun.Nicholson@kp.org> 01/19/01 09:30AM >>>
Ok
If I were setting this up I would set up 2 dialer interfaces one for the backup
circuit and one running the demand circuit.
I have never tried running them both on the same interface but as the dialer go
es into standby I would imagine that the circuit was unusable until the serial
fails but like I say I've never tried it.
I would have to ask why do you need the backup command anyway, OSPF demand circ
uit dialer is a solution on its own. The backup interface command only puts the
interface into active mode when the serial line fails so you still need traffi
c to bring the circuit up. I would certainly not block all OSPF traffic from ma
king the link active because of this reason.
If your interface ever bounces using the ospf demand circuit make sure all othe
r IP routing protocols on that router have a passive interface for the BRI. Che
ck what LSA's are bringing the line by debugging LSA generation and if thats st
ill no good use the no peer neighbor-route command that always seems to work fo
r me but you need to check the LSA generation first.
I would just use the OSPF demand circuit and forget about the backup interface
you dont need it and if I got a similar situation in the lab I would still take
that approach and then justify why I did it that way to the proctor. If I was
specificly told I had to use the backup interface and was not allowed to put OS
PF on the bri interface then I would look at the backup interface as the soluti
on.
If I was told I HAD TO use both then I would set up 2 dialer interfaces. One fo
r backup and one running OSPF demand.
But again I dont see how you could use ospf demand circuit with the backup the
interface goes int standby so becomes unusable until the interface your backing
up fails. So why use demand circuit do you see what I'm saying??? I have been
wrong and will probably be wrong again so please if this does work I'm sure som
eone will let me know.
One or the other in my opinion.
So check the wording on the lab if this was to appear and if you have to use OS
PF on the bri then OSPF demand is IMHO the only solution.
Thanks
Shaun Nicholson CCIE 6705
Lead Network Engineer
Kaiser Permanente
Silver Spring Data Center
301 680 1462
erickbe@yahoo.com on 01/18/2001 10:27:00 PM
To: ccielab@groupstudy.com@Internet
cc: (bcc: Shaun Nicholson/MD/KAIPERM)
Subject: OSPF Demand circuit on backup interface
Hello,
I have a question regarding using ospf demand circuit
on a ISDN dialer interface that is in standby mode.
Main serial interface has backup interface command.
The problem is that with the ip ospf demand circuit
command on the dialer interface the dialer interface
keeps going up and down when the primary circuit is up
and active. It is in standby mode when it does this.
With the ip ospf demand circuit command off the dialer
interface it stops going up & down and behaves like a
standby circuit should.
I have tried deny'ing OSPF in the dialer list, moving
the ip ospf demand circuit command to the remote end
router and it continues to go up & down while in
standby mode. Anyone have any ideas?
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