I want to know how L2 PDU(BPDU, VTP, CDP) pass through PW(in AToM) between PE.
Whenever the traffic from CE device enter's into mpls backbone than the complete pdu from CE will be preservered and encapsulated in new format according to forwarding table like if it is etherne than outer header will be ethernet than MPLS lable will be there and than the complete PDU from CE device. and forwarding of the layer two broadcast and multicast has to be done by backbone. in case of BPDU STP and CDP they all have multicast address in the range 01-80-c2-00-00-00 to 01-80-c2-xx-xx-xx they will be tranported accross the backbone to appropriate PE's which are discovered via the sender VE device.
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