From: Arvind Yadav (arvindyadav@comcast.net)
Date: Mon Jan 19 2004 - 04:04:42 GMT-3
I think demand ckt doesn't trigger the ISDN at all it only suppress the ospf
hello packet so that ISDN will not trigger because on hello packet. To
trigger the ISDN you need to specify the interesting traffic by using the
dialer list. That it my understanding
In this case ISDN gets triggered because whenever any FR link goes down, it
means there is change in topology OSPF flood LSA accors ISDN link which
makes the ISDN link up.
You requirement would have meet very easily by using the dialer-watch. Try
to put RA BRI and RB BRI and RC serial0 in OSPF stub no summary area. I
think in that case ISDN will only triggred when FR link b/w RA and RC fails.
Arvind
----- Original Message -----
From: "Nancy Khln" <nancy_merill@yahoo.com>
To: <ccielab@groupstudy.com>
Sent: Sunday, January 18, 2004 8:09 PM
Subject: OSPF demand!
> Hi,
>
> I have three Cisco 2500 routers using the network setup in the diagram
below:
>
> RoA-------ISDN-----RoB
> | /
> | S1
> | /
> | /
> | /
> Frame relay /
> | /
> | /
> | /
> Se1 /
> | S0
> RouterC/
>
> Requirement: I need to configure ISDN as a back up for the Frame Relay.
> Cannot use static, backup and dialer watch in the ISDN section. All ip
addreses involved in this scenario must be reachable.
> OSPF is running over the frame relay connection between Ra/Rc, Rc/Rb the
Frame connection and across the ISDN link Ra/Rb.
> , 2 parallel path exists between Ra and Rb, by configuring OSPF demand
circuit
> on the ISDN link and making sure that the ISDN link has a higher cost OSPF
path between the 2 routers, I am using the ISDN link only when
> a prefix cannot be reached over the Frame Relay link. When the Frame relay
link between Ra/Rc, or Rc/Rb goes down, OSPF demand circuit kicks in and
> the ISDN link comes up.
> So far so good, everything is working. What if I want to bring up the ISDN
link only when the frame relay link between
> Ra and Rc is down, same requirements but I want to monitor only one frame
relay link. Now the OSPF demand feature doesn help.
> What do I need to do to implement this?
> Thank you
> Nancy
>
>
>
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