Strange problem mit Cisco3745, ISDN PRI

Unanswered Question
Jul 31st, 2007


we have a Cisco 3745. When a user connects via ISDN PRI, everything is fine for about 210 Seconds. Then the users traffic is heavily disturbed. When I ping the user, every second ping gets lost, in the scheme: !.!.!.! and so on.

We tried firmware 12.4.13b and 12.4.16.

Under "show [users virtual interface]" I can see increasing input errors. The increase is analog to the pings. But they are already increasing from the beginning of the connection.

Users hardware interface:

There are no input errors on the users hardware interface. But when the disruption has started, for every outgoing ping there is shown an increase in outgoing AND ingoing packets (this happens of cours before the disruption, too). But wireshark and the ping process said, that every second packet is lost.

Wireshark sniffered on the connection between the 3745 and the switch ethernet interface.

What could be the reason for that behaviour? We have currently 10 users, so load should not be the problem.

Please tell me if I shall provide configfiles.

I have this problem too.
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Paolo Bevilacqua Tue, 07/31/2007 - 10:59

To begin with, show controllers e1.

Are you authenticating users ? Please provide the configuration dialer for isdn and dialer interface.

krauskopf.p Wed, 08/01/2007 - 00:48

Thanks for your help.

We are authenticating user with two radius servers. Other services (f.e. WLAN) are currently also authenticating against those radiusservers without noticable problems.

I attached the runningconfig and the output of show controllers e1. When the output was captured, a user was connected (with disrupted traffic).

Users are mostly connected to E1 2/0.

I attached a running-config (with passwords removed) and the output of show controllers e1.

Paolo Bevilacqua Wed, 08/01/2007 - 04:12


does this happens for ISDN, modem or both type of users ?

Anyway, i think you need to configure "dialer pool-member" under the physical interfaces, and "dialer pool" under dialer.

krauskopf.p Thu, 08/02/2007 - 05:48

It happended only for ISDN users. We restructured the config according to your advice and it solved the problem. Many thanks. :-)

jay77jay77 Mon, 08/20/2007 - 08:14

Hi Paolo

Lot of thanks for that input. It resolved my issue also.

I really salute your experience and helpfulness by sharing your knowledge.

It really saved me a lot of time and energy for me on this problem



MarkDeibert1 Thu, 08/02/2007 - 13:49

access-list WEB permit tcp eq 80

access-list TELNET permit tcp eq 23

nat (inside) 1 access-list WEB

nat (inside) 2 access-list TELNET

global (outside) 1

global (outside) 2


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