NETWORK INTERFACE WITH ADAPTIVE BRIDGE FOR EFFICIENT MAPPING OF ETHERNET PACKETS OVER AN ATM-BASED BROADBAND ACCESS NETWORK

摘要

A network interface for mapping local ethernet traffic onto an ATM-basedbroadband access network includes an adaptive MAC-level bridge that employs afast algorithm for filtering outgoing ethernet packets destined only for localdevices on the same ethernet. The network interface reads outgoing packetsreceived on a respective local ethernet segment, using the last byte of theMAC destination address of the packet header to index into a hash table of alinked list containing the first five bytes of respective stored MAC addressesof devices located on the subscriber ethernet segment. If the destinationaddress exists in the linked list, the ethernet packet is dropped, since itbelongs to the subscriber LAN segment and is not meant for further upstreamtransmission over the broadband access network. Since only the last byte ofthe destination address is used for hashing, a relatively small table of onlytwo-hundred fifty-five entries can be used to index into the remaining fivebytes of the respective stored MAC addresses, wherein the linked list keepstrack of collisions on addresses linked to the same hash value.