A. Ethernet as MAN/WAN technology
Ethernet in his long history has become dominant in enterprise networks and LAN environment but Ethernet has traditionally had a number of limitations in the MAN/WAN application. Ethernet does not scale very well to MAN/WAN networks as it uses layer 2 MAC addressing scheme, transparent bridging, spanning tree protocol and it extends broadcast domain. Moreover, Ethernet has lacked some of the dependability features necessary in service provider application, for example mechanisms to isolate one customer's traffic from another, to measure performance of a customer service instance, and to rapidly detect and repair failures in larger networks.