SHARED MEMORY MANAGEMENT IN A SWITCHED NETWORK ELEMENT

摘要

A method and apparatus for shared memory management (220) in a switched network element (100) are provided. According to one aspect of the present invention, a shared memory manager (220) for a packet forwarding device (140) includes a pointer memory (320) having stored therein information regarding buffer usage (e.g., usage counts) for each of a number of buffers in a shared memory (230). An encoder (410) is coupled to the pointer memory (320) for generating an output which indicates a set of buffers that contains a free buffer. The shared memory manager (220) further includes a pointer generator (440) that is coupled to the encoder (410) for locating a free buffer in the set of buffers. The pointer generator (440) is further configured to produce a pointer to the free buffer based upon the output of the encoder (410) and the free buffer's location within the set of buffers. According to another aspect of the present invention, a packet forwarding device (100) includes a number of output ports (117) for transmitting packets onto a network and a number of input ports (117) coupled to the output ports for receiving packets from the network, buffering the packets, and forwarding the packets to one or more of the output ports (117). The packet forwarding device (100) also includes a shared memory (230) that is segmented into buffers (140) for temporarily buffering the packets. No more than one copy of a given packet is ever stored in the shared memory (230). The packet forwarding device (100) further includes a shared memory manager (220) which dynamically allocates buffers on behalf of the input ports (117) and tracks ownership counts for each of the buffers.