The U2000 Web LCT communicates with NEs, and manages and maintains network nodes through a DCN. In the DCN, the U2000 Web LCT and NEs are considered as nodes, which are connected by using the Ethernet or DCC physical channels. In practice, the U2000 Web LCT and NEs may be located at different floors of the same building, different buildings or different cities. Hence, U2000 Web LCT and NEs are connected through a DCN, which consists of switches and routers. The DCN between the NEs is referred to as an internal DCN.