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ISDN for DSL backup

Hi all,

I have a DSL link attached to my 2600 router through a DSL modem. I have an isdn bri line on 2600 too which is supp to be used as backup line. The DSL connection is to internet. While the ISDN line terminates at a 3600. The 3600 has a connection to internet using a leased line. The DSL modem is attached to the 2600 fast ethernet port. Between the 2600 and the DSL modem is a PIX. There is no routing protocol running between the 2600 and 3600...If DSL link fails, i want the ISDN to come up (backup link). The only route on the 2600 is a default route pointing to the inside interface of the PIX. So there is no way that the router will know if the DSL link has gone down. Can any expert suggest, some method of working around with this issue, taking into consideration,

No routing protocol is to be configured.

  • Other Network Infrastructure Subjects
New Member

Re: ISDN for DSL backup

This issue has come up here and in other forums before. A Cisco TAC CCIE weighed in several months ago and at that time I think "watched routes" was the only alternative. But I do seem to recall that he mentioned a feature that was in the works. Don't know if it ever was released or if it would require a routing protocol. Might want to open a TAC case if they don't pop in on this thread. Let us know if you do.

Cisco Employee

Re: ISDN for DSL backup

There no way to configure the isdn as a backup of ethernet (dsl) connection in your case...Router need to know "some way" to determine that the dsl line went down...Here are the facts in your case.

1)Ethernet interface of 2600 will not go down at all so can't "backup interface" scheme

2)Next hop is the PIX's inside interface for 2600 so can't use "floating static route" scheme

3)No routing protocol so can't use "dialer watch" for the routing update.

There is a feature request CSCds88143 to address these scenario..Its not solved yet..Talk to your cisco rep.. to push it..

Re: ISDN for DSL backup

How do u search for a Feature request, using the request id.

Will help in any way ??

Cisco Employee

Re: ISDN for DSL backup

I haven't used Feature Nevigator much. but it helps for the feature which are already available in the ios..Try it...Thx..Tejal

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