Back up DSL line with ISDN circuit

Unanswered Question
Mar 8th, 2010

Hi all,

I am trying to configure a back up line for my Internet connection (DSL), using ISDN on a Cisco 886.

I have searched the net and many forums but  i can't find something that suits my needs.

I have tried Floating static routes, backup interface, watch list. I even checked about SLA and Policy based

Routing with multiple tracking options.

Has anybody configured something like this?

I would really appreciate any help.


I have this problem too.
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Paolo Bevilacqua Mon, 03/08/2010 - 05:46

If that is the frist time you configure cisco, I recommend you engage a reputable consultant or certified partner.

Otherwhise, there are too many confusing options for an end-user, as you noticves.

tsakoulias Mon, 03/08/2010 - 06:06

I am configuring Cisco equipment for the last 2 years. I know there are too many options but i think i can handle it.

Any advise would be helpful

Paolo Bevilacqua Mon, 03/08/2010 - 06:22

Ok. Thing is, you did not included any detail of what you want to do EXACTLY and what the problem is.

KARUPPUCHAMY MA... Mon, 03/08/2010 - 06:25


If you are going to configure PPoE method for your primary DSL link, then use backup interface option to dial ISDN and make floating static route with ISDN Gateway.

so whenever your primary link is down then those routes will be removed from your routing table and ISDN will dial automatically.Once ISDN is up, the floating static routes will be installed into your routing table,



tsakoulias Mon, 03/08/2010 - 06:59

I have configured PPPoA for my primary Dsl link (ATM interface). This link points to a dialer interface (dialer 0).

I have configured a BRI interface which points to another dialer interface (dialer 1).

I have configured one default route pointing to dialer 0 and a second default route pointing to dialer 1 with AD 100.

The problem is that dialer 0 is always up even if ATM goes down. So the floating static route feature does not work properly.

Paolo Bevilacqua Mon, 03/08/2010 - 07:21

You do that with with "IP objkect tracking" configuration. Tie the adsl default route to it.


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