Core issue
This issue is due to presence of Cisco bug ID CSCir01788.
In this issue, while you configure the ip tacacs source-interface command on Cisco 7600 series router, the % Invalid input detected at '^' marker error message appears.
This symptom is observed on a Cisco 7600 series router that runs Cisco IOS Software Release 12.2(33)SRB.
Resolution
In order o resolve this issue, upgrade Cisco IOS router to Cisco IOS Software Release 12.2(33)SRB1.
In order to download the suggested image, use the Cisco IOS Upgrade Planner.
