Microcom Systems, Inc.

Russell C Gocht

Gary B Videlock

Mark J Freitas

Douglas Wainer

Tom P Gloria

AnneMarie Freitas

A multiport source routing token ring bridge is provided which permits a single local area network bridge to interconnect to multiple remote bridges without limitations on the number of rings and bridges interspersed between a data packet's source and its intended destination. The bridge receives a packet and then scans the packet for ring-in information which matches the ring to which the bridge is attached. If this match is not successful, then the packet is not passed to the software and the address recognize and frame copy bits at the end of the packet are not set. If the match is successful, then the bridge number and next ring-in (or ring-out) segment information from the packet are used as addresses to a static RAM array. The array is preprogrammed with all valid bridge number and ring-out combinations which may be accessed by the multiport source routing bridge. If addressing of the array produces a valid indication, then the packet is passed to software for forwarding to the appropriate local area network or wide area network ports. On the other hand, if the address does not produce an indication that it can be reached through the bridge, then the hardware parses the packet to extract the next ring and bridge information, and repeats the above process until either a complete match is found and the packet is passed, or the information field is exhausted and the packet is finally rejected.

Multiport source routing token ring bridge apparatus

An apparatus and method for learning and filtering destination and source addresses in a local area network (LAN) system is provided to facilitate the transfer of information packets from one local area network to another. The apparatus provides a link between two (or more) remotely located LANS through the use of a LAN bridge. The apparatus has a LAN controller interface, a microprocessor, a state machine and one or more content addressable memories which function to monitor an information packet received from the LAN. One such apparatus is connected to each of the LANs to be interfaced and each of these apparatus to each other in order to communicate messages between the LANs. Upon detection of an information packet, the apparatus examines both the source and destination addresses of the packet. The source address is compared to a dynamically generated table of source addresses and then compared to the incoming destination address. If the destination address is found in the table of source addresses, than the packet is destined for a node on the local LAN and thus will not be sent over the bridge between the two LANs. If, on the other hand, the destination address is not in the table, the packet is forwarded to the remote LAN.

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North Attleboro, MA, United States of America

Russell C Gocht