US 5,909,686 A · Hardware-assisted central processing unit access to a forwarding database

Abstract

A method and apparatus for providing hardware-assisted CPU access to a forwarding database is described. According to one aspect of the present invention, a switch fabric provides access to a forwarding database on behalf of a processor. The switch fabric includes a memory access interface configured to arbitrate access to a forwarding database memory. The switch fabric also includes a search engine coupled to the memory access interface and to multiple input ports. The search engine is configured to schedule and perform accesses to the forwarding database memory and to transfer forwarding decisions retrieved therefrom to the input ports. The switch fabric further includes command execution logic that is configured to interface with the processor for performing forwarding database accesses requested by the processor. According to another aspect of the invention one or more commands are provided to implement the following functions: (1) learning a supplied address; (2) reading associated data corresponding to a supplied search key; (3) aging forwarding database entries; (4) invalidating entries; (5) accessing mask data, such as mask data that may be stored in a mask per bit (MPB) content addressable memory (CAM), corresponding to a particular search key; (6) replacing forwarding database entries; and (7) accessing entries in the forwarding database.

Claims23

Dependent claims

A switch fabric comprising:

a memory access interface configured to arbitrate accesses to a forwarding database memory, the accesses to the forwarding database include operations from a set of device dependent operations that are associated with the particular implementation of the forwarding database memory;
a search engine coupled to the memory access interface and to a plurality of input ports, the search engine configured to schedule and perform accesses to the forwarding database memory and to transfer forwarding decisions retrieved therefrom to the plurality of input ports;
and
command execution logic configured to interface with a processor for performing forwarding database access on behalf of the processor, the command execution logic coupled between the memory access interface and the processor, the command execution logic supporting a predetermined set of commands that are independent of the particular implementation of the forwarding database memory and performing one or more operations of the set of device dependent operations responsive to issuance of a command from the set of predetermined commands by the processor.

1 more element

A network device comprising:

a bus interface for communicating data to and from a processor;
and
a switch fabric coupled to the bus interface and configured to provide hardware-assisted processor access to a forwarding database memory, the switch fabric including
a memory access interface configured to arbitrate accesses to the forwarding database memory,
a search engine coupled to the memory access interface and to a plurality of input ports, the search engine configured to schedule and perform accesses to the forwarding database memory and to transfer forwarding decisions retrieved therefrom to the plurality of input ports, and
command execution logic coupled between the processor and the memory access interface, the command execution logic configured to support a predetermined set of commands to provide forwarding database memory accesses on behalf of the processor, the command execution logic including an interface memory comprising one or more programmable input registers and one or more output registers, the one or more programmable input registers for receiving a command of the predetermined set of commands, and data associated with the command, if any, from the processor, the one or more output registers allowing the processor to read forwarding database memory access results, if any, and forwarding database memory access status.

3 more elements

A method comprising the steps of:

a processor requesting access to a forwarding database memory associated with a switch fabric by issuing a forwarding database access command of a predetermined set of forwarding database access commands that are supported by command execution logic of the switch fabric, the predetermined set of forwarding database access commands being independent of the particular implementation of the forwarding database memory;
and
responsive to the forwarding database access command, the command execution logic accessing the forwarding database memory on behalf of the processor by performing one or more operations of a set of operations that are dependent upon the particular implementation of the forwarding database memory.

Dependencies are inferred from the claim text.

Hardware-assisted central processing unit access to a forwarding database

Life of this patent

Hardware-assisted central processing unit access to a forwarding database

Life of this patent

Abstract

Claims23