US 5,757,795 A · Method and apparatus for hashing addresses in a network switch

Abstract

A hash system for selecting a destination network port for each of a plurality of binary address values, such as media access control (MAC) addresses, received by a plurality of network ports including a hash memory for receiving binary hash values and for providing a corresponding port number identifying a destination network port. Each of the network ports includes hash logic for receiving a binary address value, for selecting a subset of bits of each received binary address value as a binary hash value, for providing the binary hash value to the hash memory and for receiving a corresponding port number. The subset of bits are determined by a bit enable value. The hash system further includes processor logic for sorting the binary address values among the network ports, for determining and periodically updating the bit enable value to optimize uniqueness of correspondingly updated binary hash values corresponding to the binary address values, for providing updated bit enable values to the hash logic of each of the plurality of network ports and for programming the hash memory according to the updated binary hash values. The processor periodically performs a single-bit comparison and a double-bit comparison for updating the bit enable value.

Claims20

Dependent claims

A hash system for selecting a destination network port for each of a plurality of binary address values received by a plurality of network ports, comprising:

a hash memory for coupling to each of the plurality of network ports, for receiving binary hash values and for providing a corresponding port number identifying a destination network port;
each of the plurality of network ports including hash logic for receiving a binary address value, for selecting a subset of bits of each received binary address value as a binary hash value, said subset of bits being determined by a bit enable value, for providing said binary hash value to said hash memory and for receiving a corresponding port number;
and
processor logic for coupling to each of said plurality of network ports and to said hash memory for sorting the plurality of binary address values among the plurality of network ports, for determining and periodically updating said bit enable value to optimize uniqueness of correspondingly updated binary hash values corresponding to the plurality of binary address values, for providing updated bit enable values to said hash logic of each of the plurality of network ports and for programming said hash memory according to said updated binary hash values.

1 more element

A network switch for transferring data packets between a plurality of network segments, each of the data packets including source and destination media access control (MAC) addresses, the network switch comprising:

a hash memory for receiving a binary hash value and for providing a corresponding port number;
a plurality of network ports coupled to said hash memory for receiving and transmitting data packets, each of said plurality of network ports including hash logic for retrieving a destination MAC address from each data packet received, for selecting a subset of bits of said destination MAC address as a binary hash value, said subset of bits being determined by a bit enable value, for providing said binary hash value to said hash memory and for receiving a corresponding port number corresponding to another one of said plurality of network ports;
switch fabric coupled to said plurality of network ports for transferring data packets between said plurality of network ports;
and
processor logic coupled to each of said plurality of network ports and to said hash memory for sorting received MAC addresses among said plurality of network ports, for determining and periodically updating said bit enable value to optimize uniqueness of correspondingly updated binary hash values corresponding to received MAC addresses, for providing updated bit enable values to said hash logic of each of said plurality of network ports and for programming said hash memory according to said updated binary hash values.

2 more elements

Dependencies are inferred from the claim text.

Method and apparatus for hashing addresses in a network switch

Life of this patent

Method and apparatus for hashing addresses in a network switch

Life of this patent

Abstract

Claims20