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New Member

ISDN Dial Back-Up

I have to set-up dial back up for our Oregen office. currently they connect to us via a full T1 (Frame Relay).

If that goes down, then they need to connect to our HQ office via isdn.

Oregen currently has an 2 ISDN BRI's connected to a 3640 for their remote access users.

HQ currently has an ISDN PRI to a 3640 for remote access as well.

All remote users authenticate with a SecureID card to a radius server located at HQ.

Can I use this current configuration to allow Oregen to do ISDN dial backup?

Does Oregen have to authenticate to the radius server and put in the user id / secure ID numbers somehow or could there be an easier solution?

Any help would be appreciated.



Re: ISDN Dial Back-Up


Oregon can authenticate using the Radius server very easily. Simply add the Oregon router as a user in your Radius server, and configure HQ and Oregon as described in this section about PPP authentication:

Good Luck.


New Member

Re: ISDN Dial Back-Up


Thanks for the link.

So would it be possible to configure the Oregon router and the radius server (HQ side) with a username and password to authenticate on dial up?

If so, which interface should the username and password be configured on?

Would this affect remote users that use secureID cards to authenticate?

Thanks very much!


Re: ISDN Dial Back-Up

Yes you can do it very easily.

When you use PPP authentication, use the following..

ppp authentication chap Test

where Test is a list name defined using AAA commands.

aaa new-model -- to enable AAA

aaa authentication ppp Test group radius

Now create a username/password for the Oregon router in your Radius server.

Hope that helps

New Member

Re: ISDN Dial Back-Up

Thanks for the Authentication Information.

A few other questions that I have are:

Instead of using the Radius Server to authenticate, can I use the HQ 3640 Router instead? If so, how?

If The primary link comes back up, will the ISDN call then drop on it's own?

Also if using OSPF, will it pick the T1 when it becomes available even if the ISDN line is still connected?


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