carrier Ethernet switch-router (CESR)
Carrier EthernetSwitch Routers(CESR) are switch components used in Carrier Ethernet( CE); both in the Provider Networks and in the Carrier Networks.
Carrier Ethernet Switch Routers (CESR) are connected to the Carrier Ethernet Access Switches( CEAS) or to each other and can forward the extended frames from the local Provider Bridges or encapsulate them in the Provider Backbone Bridge( PBB) frame. Carrier networks use the Carrier Ethernet switch routers to transport the data packets between different provider networks using the Provider Backbone Transport( PBT).
Carrier Ethernet switch routers extend the frame received from Carrier Ethernet access switches to include the backbone source address (B- SA) and the backbone destination address (B- DA), as well as the VLAN identifier (B- VID) and the I-component service identifier (I- SID).