We are unable to login thru TACACS when we are connected thru serial link but the TACACS authentication happens when we use ISDN. The issue is observed at 2 locations, other locations are working fine and configuration seems to be ok. We have ACS installed on windows as TACACS server. One more thing which is noticable is that when we chack the logs in ACS it shows the part of Banner in the Username field of Failed Authentication.csv file.
Pls. let me know is someone had faced the similar issue and how it was resolved.
Thanking u in anticipation.