nas1 ==> localhost
nas2 ==> 200.300.xxx.1
sqlippool
UserName NASIPAddress CallingStationID pool_key
user1 127.0.0.1 111.111.111.22 5
user2 127.0.0.1 222.222.222.22 4
user3 127.0.0.1 333.333.333.22 7
user4 login ...........
user3 NASIPAddress CallingStationID => blank
user3 pool_key ==> 0
user4 pool_key ==> 7
sqlippool
UserName NASIPAddress CallingStationID pool_key
user1 127.0.0.1 111.111.111.22 5
user2 127.0.0.1 222.222.222.22 4
user4 127.0.0.1 444.444.444.22 7