From: ccie2be (ccie2be@nyc.rr.com)
Date: Sun Jul 11 2004 - 08:22:18 GMT-3
Hi Akbar,
I have thought about the same thing not so long ago.
Here's how I understand this.
In many respects, these 2 commands are functionally redundant - in other
words, they accomplish the same thing but use different methods to do so.
That said, I can imagine there are situations where you have to use dialer
watch instead of ospf demand circuit. One possible situation is where the
watched route isn't an ospf route. I've never actually seen this situation,
but here's my thinking.
ospf demand circuit will trigger a call only when there's a change in the
ospf topology. But, suppose dialer watch is configured to watch a route
that isn't an ospf route or a route redist into ospf. In this case, the
ospf topology might not change so with ospf demand circuit configured, a
call is NOT triggered. But, with dialer watch configured, a call is
triggered if the watched route disappears from the route table.
Again, let me emphasize that I've never actually seen a network where dialer
watch would work but ospf demand circuit wouldn't work, but I can imagine
Cisco could design a lab in which this could be the case.
However, if the network is a pure ospf network, then I believe either method
would work and there would be no reason to configure both. But, if you were
configuring dialer watch to trigger the isdn circuit, then you would need to
make sure ospf traffic was defined to not be interesting traffic because
otherwise the ospf hello's would keep bringing up the isdn circuit.
I would certainly be interested in knowing if others have a different
opinion.
HTH, Tim
----- Original Message -----
From: "akbar khan" <ciscokhan@hotmail.com>
To: <ccielab@groupstudy.com>; <security@groupstudy.com>
Sent: Saturday, July 10, 2004 1:52 PM
Subject: OSPF Demand Circuit with Watch List..
> Hello Folks, Is it reasonable to use dialer watch-list with Demand
> Circuit. Ex: R1---ISDN---R2 & R1----FR----R3-----FR----R2 (Hub &
> Spoke) running OSPF on all the links. I have configured R1 BRI for Demand
> circuit to fire for any ospf topology change. In addition I am watching
> the Loopback of R2 with watch list. My question is that if there is a
> toplogy change somewhere in the ospf domain except the loopback of R2
> does my R1 will trigger the call with the stipulaiton that it is already
> configured with watch-list.. I mean can my BRI will trigger the call for
> both topolongy change or in the loss of R2 Loopback...? Many thanks and
> Regards in Advance, Akbar khan
>
> ------------------------------------------------------------------------
>
> Add photos to your messages with MSN 8. Get 2 months FREE*.
>
> _______________________________________________________________________
> Please help support GroupStudy by purchasing your study materials from:
> http://shop.groupstudy.com
>
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sun Aug 01 2004 - 10:11:52 GMT-3