"iSmart inserts home-port identity information into the PAP authentication packet and relays the information to the
PPPoE server. Home-port identity information includes the AN-2000 node ID as well as the shelf, slot and port index
of the home port. This information is inserted into the username field of the PAP authentication request.
The operator
can provision the system to replace the original user name with home-port identity information, or to append the
home-port information in front of the original user name. Each DSL port can be independently provisioned to turn
iSmart on or off and, if turned on, to either replace the user name or append the home-port to the original user name"
The An-2000 is the DSLAM model number.Hope this helped you understanding port binding a little better.