ISDN BRI Issue

Unanswered Question
Sep 16th, 2008

Hi Experts

my customer has complained that Telecom has been charged them huge amount of bills for their ISDN BRI link in the month of July, August and most probably this month.When quried, the Telecom blamed this has being caused by the router configurations and the calls amounts represent every call made lasting about 21 seconds and in intervals of 9 seconds, sometimes 14 seconds all hours of the day.

The ISDN BRi link is between two sites (Site A & Site B) and is a backup link to a Leased line. This link has not been utilized ever since it was commissioned as we've never had any problems with the the Leased line.

Please look at the configurations of both sites, attached, and identify to me which line in the config is causing this to happen. I'm no expert in ISDN BRI.

I have this problem too.
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Richard Burts Tue, 09/16/2008 - 19:03

Bernadette

I have looked at the configs that you posted and I believe that I see your problem. I would explain it with these points:

- the subnet on the dialer interface is 160.8.200.144/30

- the network statement under router eigrp is:

network 160.8.0.0.

- so the subnet of the dialer interface matches the eigrp network statement and therefore the router is attempting to run eigrp on the dialer interface. And it is attempting to send eigrp hello messages over the interface.

- the dialer-group and dialer-list are a simple protocol ip permit. So the eigrp hello messages are interesting traffic and will bring up the BRI interface.

The solution to the problem is to change the dialer list so that it references an extended access list. In the access list you need to deny eigrp as interesting traffic and then permit other traffic. The access list might look something like this:

access-list 101 deny eigrp any any

access-list 101 permit ip any any

HTH

Rick

bericaleb Tue, 09/16/2008 - 19:37

Thanks Rick for your reply.

Do I configure this on both site routers?

Richard Burts Wed, 09/17/2008 - 10:46

Bernadette

Yes you would need to configure this on both site routers.

HTH

Rick

shillyar Wed, 09/17/2008 - 10:25

Hello,

Also add this to access-list 101, access-list 101 deny ip any host. Make sure you do this on both side of the ISDN link.

Thanks Steve

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