Method and apparatus for source filtering data packets between networks of differing media
DCFirst Claim
1. In a communication system having a plurality of data networks interconnected for communicating packets of data, each packet containing a source address of a sender, a data packet and a destination address of a receiver for the data packet, a method comprising:
- at a media access controller for interconnecting one data network of a plurality of data networks to at least a second data network of the plurality of data networks, receiving a data packet from the second data network;
examining the data packet for a source address contained in the data packet;
looking up, in a directory table stored at the controller, the source address for obtaining source filtering information relating to the source, the step of looking up comprising the steps of,arithmetically coding, according to a predetermined model, the source address as a numerical value uniquely identifying a record of data containing source filtering information for the source address, andaccessing the record of data identified by the numerical value for retrieving the source filtering information associated with the source address; and
determining whether or not any nodes of the first data network which are connected to the controller are protected from receiving the data packet from the source.
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Abstract
To provide for fast access times with very large key fields, an associative memory utilizes a location addressable memory and look up tables to generate from a key an address in memory storing an associated record. The look up tables, stored in a memory, are constructed with the aid of arithmetic data compression methods to create a near perfect hashing of the keys. For encoding into the look up table, keys are divided into a string of symbols. Each symbol is assigned an index value, such that a modulo sum of index values for symbols of a particular key is a unique value that is used as an address to the memory storing the record associated with that key.
184 Citations
13 Claims
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1. In a communication system having a plurality of data networks interconnected for communicating packets of data, each packet containing a source address of a sender, a data packet and a destination address of a receiver for the data packet, a method comprising:
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at a media access controller for interconnecting one data network of a plurality of data networks to at least a second data network of the plurality of data networks, receiving a data packet from the second data network; examining the data packet for a source address contained in the data packet; looking up, in a directory table stored at the controller, the source address for obtaining source filtering information relating to the source, the step of looking up comprising the steps of, arithmetically coding, according to a predetermined model, the source address as a numerical value uniquely identifying a record of data containing source filtering information for the source address, and accessing the record of data identified by the numerical value for retrieving the source filtering information associated with the source address; and determining whether or not any nodes of the first data network which are connected to the controller are protected from receiving the data packet from the source. - View Dependent Claims (2)
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3. In a communication system comprised of a plurality of data networks interconnected for communicating packets of data, a routing method comprising:
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receiving a data packet at a node connecting at least a first one of the plurality of data networks to a second one of the plurality of data networks, the data packet including a physical address for identifying a device to which the data packet is to be routed and a first logical address for identifying a sender of the data packet independent of the sender'"'"'s physical address; examining the data packet for the first logical addresses; looking up, in a directory table stored at the node, source filtering information associated with the first logical address; and filtering the data packet in response to the source filtering information. - View Dependent Claims (4, 5, 6, 7)
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8. In a communication system having a plurality of data networks interconnected for communicating packets of data, a controller for interconnecting a first data network of the plurality of data networks to at least a second data network of the plurality of data networks comprising:
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means for receiving a data packet, the data packet including a physical media address for identifying a physical device for routing the data packet in physical media and a source address for logically identifying a sender of the data packet independent of the sender'"'"'s physical media address; means for looking up in a directory table stored at the controller using the source address source filtering information associated with the source address; and means for filtering the data packet in response to the source filtering information. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification