DSL router with ISDN backup

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- Bob Smith
  
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posted
17 years ago

Tue, Oct 31, 2006 9:38 PM

Hi all,

Been pulling my hair out for a few days on this now..

Have 2x sites connected via aDSL using VPN. This works great... (2x 1841 units)

However, i have a problem with 1 of the dsl lines and its currently down :(

I have ISDN modules in each of the routers, and also a ISDN line at each site, what i want to do is temporily get the link working, is to get the routers to dial each other over ISDN.

I've been looking at treating it as a backup-interface to the dsl, so that when the dsl isn't in sync (therefore down) the backup-interface comes up and dials up..

But this isnt working, is it because the interface has a cyrpto-map on it, which is coming from the wrong ip when connected over dsl direct to each router?

Anyone have any configuration examples to make this work or any suggestions, this has become a nightmare for me!

- D
- Doug McIntyre
  
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posted
17 years ago

Wed, Nov 1, 2006 4:13 AM

Long ago, I tried to get any sort of dial-on-demand working with reguard to ADSL cards in Cisco routers, and gave up. It just never seemed to work, even though the same config around something like a BRI line worked perfectly fine.

I figure Cisco never implemented anything dial-on-demand in the ADSL driver code properly, figuring it was virtually a leased-line, and never needed tracking that way, and anything invoking dial-on-demand around a DSL line always silently fails.

Your best option is to probably use the router-tracking objects now.

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- Thrill5
  
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posted
17 years ago

Wed, Nov 1, 2006 5:39 AM

You can also use "floating statics"....

For example if have something like...

ip route 0.0.0.0 0.0.0.0 10.1.1.1

That points to your tunnel interface you could then add

ip route 0.0.0.0 0.0.0.0 10.2.2.1 100

which would point to your dialer interface that you create for the BRI interface. This static has a metric of "100" which would only be in effect if the other default route was "down".

Scott