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Method and device for routing or compressing packets destination address containing classless address

  • US 7,289,502 B1
  • Filed: 10/04/2000
  • Issued: 10/30/2007
  • Est. Priority Date: 10/04/2000
  • Status: Expired due to Fees
First Claim
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1. A method of routing packets with a destination address (2, 2A, 2B) through an electronic routing device, said packets destination address comprises bit packets and wherein said address is a classless address indicative of a desired destination, said routing device having at least a database (10) of prefix entries, said entries corresponding to a desired output data link, wherein said method for each packet destination address (2, 2A, 2B) comprises the steps of:

  • generating an address mask (3, 3A, 3B-C, 6A-I) having a number of bits equal to that of the packets destination address (2, DA, 2B) and comprising two portions;

    a first portion (14, 14A) starting from bit 0 (MSB) and ending with a bit (n−

    1)−

    i, and a second portion (15, 15A) starting from bit n−

    i and ending with bit n−

    1, wherein the first portion (14,14A) comprises only a non masking value and the second portion (15, 15A) comprises only a masking value,i being an integer comprised between 0 and n−

    1,wherein i=0 in the first iteration, and i being incremented by one for each subsequent iteration until a match is found or it has reached a fixed value (n−

    1);

    continuing to generate an address mask (3, 3A, 3B-C, 6A-1) until an entry, matching a masked address (1, 1A) obtained by performing a masking operation on said packet destination address (2, 2A, 2B) and said address mask (3, 3A, 3B-C, 6A-1), is found in said data base (10);

    wherein said masking operation is an AND operation if a masking value is 0 and a non masking value 1, said masking operation is an OR operation if the masking value is 1 and the not masking value 0, and the packets destination address and the address mask are negated before being inputted to the OR operation and the output of said OR operation is negated;

    stopping, if a match is found, said generation of address masks (3, 3A, 3B-C, 6A-I) and outputting the output data link corresponding to said match; and

    outputting, if no match is found or i is equal to said fixed value (Nbit), a message indicating that no output data link was found.

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