3Com Corporation

Synernetics Inc.

Shannon Q Hill

Christopher P Lawler

R Bruce McClure

David Lipschutz

John A Flanders

Stephen L Van Seters

Robert Millard France

Thomas A Radogna

A method and cache management for a bridge or bridge/router providing high-speed, flexible address cache management. The unit maintains a network address cache and an age table, searches the cache for layer 2 and layer 3 addresses from received frame headers, and returns address search results. The unit includes an interface permitting processor manipulation of the cache and age table, and supports a 4-way set associative cache to store the network addresses. A plurality of functions implemented in hardware enables software manipulation of the associated cache. Four cache operating modes are selectable. The unit can identify and select destination ports within a Load Balanced Port Group for frame forwarding. The unit utilizes Virtual LAN identification in conjunction with a MAC address for lookup in the cache. A cyclic redundancy code for each address to be looked up in the cache is used as an index into the cache. If a cache thrash rate exceeds a predetermined threshold, CRC table values can be rewritten. Four time-sliced cache lookup units are provided, each consisting of a cache lookup controller for comparing a received network address to an address retrieved from an identified cache set.

High speed cache management unit for use in a bridge/router

An address management circuit and method of operation, for use in a communications internetworking device, includes a search engine having first and second search circuits for concurrently searching a network address table for source and destination addresses of a frame received by the communications internetworking device. Memory read cycles of the source and destination address searches are interleaved to allow a memory access to occur during every system cycle to thereby rapidly complete the searches for both the source and destination addresses.

Apparatus and method for processing data frames in an internetworking

A network interface for connecting a first network utilizing a first medium access control protocol to a plurality of relatively slower networks utilizing a second medium access control protocol. The network interface includes memory in which a table of addresses of nodes on the plurality of second networks is maintained. The network interface passes data from a data packet received from the first network to one of the plurality of second networks only if the destination address of the data packet matches one of the node addresses within the table of node addresses. The network interface passes data from a data packet received from one of the plurality of second networks to the first network only if the destination address of the data packet does not match a node address in the table of node addresses. The network interface passes data from a data packet received from one of the plurality of second networks to another of plurality of second networks only if the destination address of the data packet matches a node address in the table of node addresses.

Network multiplexer

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Westford, MA, United States of America

Shannon Q Hill