Disposition filtering of messages using a single address and protocol table bridge

Claim 2

Bridging apparatus having two ports for coupling to a first medium and a second medium, said apparatus providing selective filtering of messages transmitted between stations on said media, each of said messages including a destination address and a protocol-type code, said apparatus comprising: means for receiving a message from said first medium; a single content addressable memory (CAM) table for storing a message filtering database, said single CAM table having a plurality of database entries capable of supporting each of the two ports of said apparatus, said database entries including: a first portion of entries containing addresses of the stations connected to only one of said first and second media; and a second portion of entries containing protocol-types within the stations connected to said first and second media, said second portion of entries having asserted first and second flags to distinguish said protocol-types from said addresses; storage means for storing disposition information associated with each of said protocol-types stored in said database entries; means for comparing said received message with said addresses and protocol-types stored in said database entries; and means responsive to said comparison means for selectively disposing of each received message in accordance with said disposition information, said selectively disposing means forwarding said message to said second medium when one of: said protocol-type of said message does not match one of said protocol-types of said database entries; and said protocol-type of said message matches one of said protocol-types of said database entries and said disposition information associated with said protocol-type specifies forwarding said message to said second medium.

Claim 3

A bridge for coupling a first network to a second network, said bridge comprising: a bus; a message filtering database coupled to said bus, said message filtering database having a plurality of database entries including: address entries containing addresses of the stations connected to one of said networks; and protocol-type entries containing protocol-types within the stations connected to said one network; a memory, coupled to said bus, for storing disposition information associated with each of protocol-type entry; a plurality of port controllers, coupled to said bus, for receiving and transmitting a message between said networks, said port controllers configured to perform direct memory access (DMA) requests in said memory; and a multi-stage control unit, coupled to said bus, for executing message filtering operations of said bridge in response to said DMA requests.

Claim 4

A bridge for coupling a first network to a second network, said bridge comprising: a bus; a message filtering database coupled to said bus, said message filtering database having a plurality of database entries including: address entries containing addresses of the stations connected to one of said networks; and protocol-type entries containing protocol-types within the stations connected to said one network; a memory, coupled to said bus, for storing disposition information associated with each of protocol-type entry; a plurality of port controllers, coupled to said bus, for receiving and transmitting a message between said networks, said port controllers configured to perform direct memory access (DMA) requests in said memory; and a multi-stage control unit, coupled to said bus, for executing message filtering operations of said bridge in response to said DMA requests.

Claim 5

The bridge of claim 2 wherein said multi-stage control unit comprises a memory allocation stage for responding to DMA requests from said port controllers in response to reception of said message, said memory allocation stage initiating time-multiplexed transfer of said message over said bus to said memory.

Claim 6

The bridge of claim 3 wherein said multi-stage control unit further comprises an address filtering stage, coupled to said memory allocation stage, for executing time-multiplexed comparison operations between a destination address of said message and said address entries of said database over said bus.

Claim 7

The bridge of claim 4 wherein said multi-stage control unit further comprises a protocol-type filtering stage, coupled to said address filtering stage, for executing time-multiplexed comparison operations between a protocol-type of said message and said protocol-type entries of said database over said bus in response to a match between said destination address and one of said address entries.

Claim 8

The bridge of claim 5 wherein said multi-stage control unit further comprises a message disposition stage for disposing,of said message in accordance with results of said address filtering and protocol-type filtering stages.

Claim 9

A bridge for coupling a first network to a second network, said bridge comprising: a bus; a message filtering database coupled to said bus, said message filtering database having a plurality of database entries including: address entries containing addresses of the stations connected to one of said networks; and protocol-type entries containing protocol-types within the stations connected to said one network; a memory, coupled to said bus, for storing disposition information associated with each of protocol-type entry; a plurality of port controllers, coupled to said bus, for receiving and transmitting a message between said networks, said port controllers configured to perform direct memory access (DMA) requests in said memory; and a multi-stage control unit, coupled to said bus, for executing message filtering operations of said bridge, said control unit including: a memory allocation stage for responding to DMA requests from said port controllers in response to reception of said message, said memory allocation stage initiating time-multiplexed transfer of said message over said bus to said memory; an address filtering stage, coupled to said memory allocation stage, for executing time-multiplexed comparison operations between a destination address of said message and said address entries of said database over said bus; a protocol-type filtering stage, coupled to said address filtering stage, for executing time-multiplexed comparison operations between a protocol-type of said message and said protocol-type entries of said database over said bus in response to a match between said destination address and one of said address entries; and a message disposition stage for disposing of said message in accordance with results of said address filtering and protocol-type filtering stages.

Claim 10

A bridge for coupling a first network to a second network, said bridge comprising: a bus; a message filtering database coupled to said bus, said message filtering database having a plurality of database entries including: address entries containing addresses of the stations connected to one of said networks; and protocol-type entries containing protocol-types within the stations connected to said one network; a memory, coupled to said bus, for storing disposition information associated with each of protocol-type entry; a plurality of port controllers, coupled to said bus, for receiving and transmitting a message between said networks, said port controllers configured to perform direct memory access (DMA) requests in said memory; and a multi-stage control unit, coupled to said bus, for executing message filtering operations of said bridge, said control unit including: a memory allocation stage for responding to DMA requests from said port controllers in response to reception of said message, said memory allocation stage initiating time-multiplexed transfer of said message over said bus to said memory; an address filtering stage, coupled to said memory allocation stage, for executing time-multiplexed comparison operations between a destination address of said message and said address entries of said database over said bus; a protocol-type filtering stage, coupled to said address filtering stage, for executing time-multiplexed comparison operations between a protocol-type of said message and said protocol-type entries of said database over said bus in response to a match between said destination address and one of said address entries; and a message disposition stage for disposing of said message in accordance with results of said address filtering and protocol-type filtering stages.

Claim 13

The method of claim 8 wherein said step of disposing of the received message in accordance with said disposition information comprises the step of discarding the received message.

Claim 14

The method of claim 8 wherein said step of disposing of the received message in accordance with said disposition information comprises the step of discarding the received message only if the message is a multicast message.

Claim 15

Bridging apparatus having two ports for coupling to a first medium and a second medium, said apparatus providing selective filtering of messages transmitted between stations on said media, each of said messages including a destination address and a protocol-type code, said apparatus comprising: A. means for receiving a message from said first medium; B. a single table for storing a message filtering database, said single table having a plurality of database entries capable of supporting each of the two ports of said apparatus, said database entries comprising B1. a first portion of entries containing addresses of the stations connected to only one of said first and second media; and B2. a second portion of entries containing protocol-types within the stations connected to said first and second media, C. storage means for storing disposition information associated with each of said protocol-types stored in said database entries; D. means for comparing said received message with said addresses and protocol-types stored in said database entries; E. means responsive to said comparison means for selectively disposing of each received message in accordance with said disposition information by forwarding said message to said second medium when one of said protocol-type of said message does not match one of said protocol-types of said database entries; and said protocol-type of said message matches one of said protocol-types of said database entries and said disposition information associated with said protocol-type specifies forwarding said message to said second medium.

Claim 16

Bridging apparatus having two ports for coupling to a first medium and a second medium, said apparatus providing selective filtering of messages transmitted between stations on said media, each of said messages including a destination address and a protocol-type code, said apparatus comprising: A. means for receiving a message from said first medium; B. a single table for storing a message filtering database, said single table having a plurality of database entries capable of supporting each of the two ports of said apparatus, said database entries comprising B1. a first portion of entries containing addresses of the stations connected to only one of said first and second media; and B2. a second portion of entries containing protocol-types within the stations connected to said first and second media, C. storage means for storing disposition information associated with each of said protocol-types stored in said database entries; D. means for comparing said received message with said addresses and protocol-types stored in said database entries; E. means responsive to said comparison means for selectively disposing of each received message in accordance with said disposition information by forwarding said message to said second medium when one of said protocol-type of said message does not match one of said protocol-types of said database entries; and said protocol-type of said message matches one of said protocol-types of said database entries and said disposition information associated with said protocol-type specifies forwarding said message to said second medium.