Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

ACS authentication failure with two dialup routers

Hi all,

Initially i have only one dailup routerA(Class B subnet) authenticate with my ACS. Then my company bought another dialup routerB(Same Class B subnet) for load balancing.

Seems that now when a user dial up, he will have an entry on both the Failed authentication log as well as the Passed authentication log. This only happen when the new router is added into the network.

Note that I have two entries in my NAS for both my dialup routers.

Please assist.

Cisco Employee

Re: ACS authentication failure with two dialup routers

If i understand your problem correctly, you are saying, you are getting 2 log entries for every dialup client when using the new router? if yes, then, they are probably not for the same session or authentication request. Let me explain further. When a dialup connection comes in, the NAS (router) sends an AUTHENTICATION request to the ACS, if for some reason, the ACS does not reply withing the due time (default is 5 seconds), then it re-sends another try. So, probably what might be happening in your case is that you are getting a failed attempt for the first session and then when the reattempts are made, it eventually succeeds and you get both the logs, the PASS & FAIL.

To check futher, turn on following debugs and you might get more visitbility;

- debug aaa authentication

- debug aaa authorization

- debug ppp authentication

- debug ppp negotiation

- debug radius or tacacs



New Member

Re: ACS authentication failure with two dialup routers


I have not check the timing for the failed logs and successful logs.

If there any way to change the timing?? My ACS is behind a firewall in my internal LAN.

For your assistance, pls. Thank you.

Cisco Employee

Re: ACS authentication failure with two dialup routers

Turn on FULL Log level under 'Service Control' settings in 'System Configuration'

You can also set the Date Formal control in 'System Configuration'.


CreatePlease to create content