Hi Ahsan, can you be more specific, when you say track users who use edge routers do you mean who logs into these routers? if so there are several methods but you could simply use the esiest one to setup by creating local users on routers and define privilege levels which especifies access level to make chnages to the routers or simply look at logs or interface statistics based on privilege levels. If this is not what you are looking for please be more especific to point you to the right direction.

This is an example of creating local users.

username Joe privilege 15 password XXXXX

username Joe2 privilege 5 password XXXXX

Refer to privilege levels for more info

http://www.cisco.com/en/US/docs/ios/12_2t/12_2t13/feature/guide/ftprienh.html

If this is what you are looking for let me know to provide some additional information on above subject.

Rgds

Jorge