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New Member

Urgent help: ISDN backup for VPN


I have a setup like this:

------ watched ----------- --------------- -------------

PIX | ---- subnet -------| router 1|--------|ISP Cloud |-------| router2 |

------ ---------- ----------- -------------- -------------

router 1 and 2 connect to ISP with frame-relay. They areon different subnets

Between PIX and router2 I have VPN. I want to create a backup solution with ISDN for the VPN.

Both routers have default routes pointing to the ISP side of the Frame-relay connection.

Also router 1 is the HQ router where multiple sites terminate traffic.

I have created a GRE tunnel between router 1 and 2, and OSPF is running on both. Also I configured

dialer-watch on router 2 to detect the disappearnce of watched subnet and dial to router 1.

(something witch it does, when I shutdown the serial interface on router 1 or apply an access list)

The problem I'm facing is the following:

The conection might go down without affecting the status of the frame-relay interfaces

(something might happen int the ISP cloud).

How I'm going to route traffic from the main connection to the ISDN connection, especially on router 1, where

ip route dialer0 200 will not be helpful at all.

Any clues? I'll appreciate it.

If someone interested to help I can email the router configs.

This issue has been torturing me for 2 weeks, yet no solution.

Thanx for any help.

New Member

Re: Urgent help: ISDN backup for VPN

I would think that your remote site (router2) would advertise it's local routes over the ISDN when dialed up. And if the connection is broken (not reciving routes over the VPN) then the only route for Router1 to the remote site would be over the ISDN. I don't see (or understand) your problem.

Cisco Employee

Re: Urgent help: ISDN backup for VPN

Here's a sample config I wrote on what you are trying to configure.

Configuring IPSec Redundancy over ISDN Using Dialer Watch



New Member

Re: Urgent help: ISDN backup for VPN

thanx guys for your help.

I hadn't explained the problem well.

Dialer watch is working fine. But the problem is that behind router 2 and the PIX I have NAT. So I can't advertise those networks to router 1, as the NAT-ed addresses are transparent to it because of IPSec.

IF I shut down the main interface on router 2, I'm able to ping addresses behind the PIX, although the reverse is not working, as it's being directed to the serial interface of router 1.

If I shut down the main interface on router 1, nothing is happening as the packets are being directed to the serial interface .

Was I clear?

I appreciate any help


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