A VPLS service emulates a LAN or the functionality of an Ethernet switch. An Ethernet switch has the following characteristics:
Forwarding of Ethernet frames
Forwarding of unicast frames with an unknown destination MAC address
Replication of broadcast and multicast frames to more than one port
Dynamic learning of MAC addresses
MAC address aging
VPLS should also have these characteristics. Ethernet frames receive two MPLS labels before they are forwarded across the MPLS backbone. This forwarding of Ethernet frames is the same as in Chapter 10, “Any Transport over MPLS.” An imposed virtual circuit (VC) label always serves as a demultiplexing label and indicates the VC that the frame belongs to. The tunnel label is ...