Abstract: A network node includes a central processor card and a plurality of line cards. Each line card generates a maintenance association end point (MEP) entity that can respond to connectivity fault management (CFM) frames. The MEP entity on each line card periodically generates and transmits a multicast connectivity check message (CCM) to the other line cards in the network node. The CCM includes a card-information TLV and, optionally, a trunk-status TLV. Card-information TLVs include the slot number and card type of the transmitting line card. Trunk-status TLVs include the trunk state of each trunk supported by the transmitting line card. The line cards of the node consider a given line card to be down when three consecutive CCMs from that line card are missed. In response to recognizing a down line card, the other line cards can initiate an action, such as determine the trunks supported by the down line card and trigger a trunk switchover.

Abstract: OAM may be implemented at an intermediate node on a PBT trunk in an Ethernet network by causing OAM frames to be addressed to the PBT trunk endpoint but causing the OAM frames to carry an indicia (Ether-type, OpCode, TLV value or combination of these and other fields) that the OAM frames are intended to be used for intermediate node OAM functions. The Ether-type, OpCode, and TLV values may be standardized values, or vendor specific values such as OpCode=51 or TLV=31 may be used. Addressing the OAM frames to the PBT trunk end point enables the OAM frames to follow the PBT trunk through the network. The OAM indicia signals to the intermediate nodes that the OAM frames are intended to be used to perform an intermediate node OAM function. The OAM frames may contain reverse trunk information to prevent the intermediate nodes from being required to store correlation between forward and reverse PBT trunks.