Method and apparatus for reducing pool starvation in a shared memory switch

A method comprising:

• logically portioning a shared memory into a number of reserved pools and other pools;
• receiving a number of buffer pool selection determinants, said selection determinants including counter status information and egress port forwarding information, said egress port forwarding information dependent upon a header of an accepted data packet to be stored in a buffer;
• selecting either one of the reserved pools or one of the other pools from which to allocate the buffer for data based on said selection determinants, and said egress port forwarding information only having direct consequence on the selecting of the pool when the selecting is from the reserved pools;
• and
• allocating the buffer from the selected pool.

A switch comprising:

• a plurality of egress ports;
• a shared memory configured to be logically portioned into reserved pools of buffers and other pools of buffers, and each one of the reserved pools of buffers being reserved for a respective one of the egress ports;
• an information receiver for receiving a number of buffer pool selection determinants, said selection determinants including counter status information and egress port forwarding information, said egress port forwarding information dependent upon a header of an accepted data packet to be stored in a buffer;
• and
• logic for selecting either one of the reserved pools or one of the other pools from which to allocate the buffer for data based on said selection determinants, and said egress port forwarding information only having direct consequence on the selecting of the pool when the logic selects from the reserved pools.

A switch comprising:

• a plurality of ingress ports;
• a plurality of egress ports;
• and
• a shared memory configured to be logically portioned into:
• i) a plurality of reserved pools of buffers, each reserved pool of buffers associated with a respective one of the plurality of egress ports and reserved to store data to be forwarded to the respective egress port;
• ii) a shared pool of buffers reserved to store data to be forwarded to any of the plurality of egress ports;
• and
• iii) a multicast pool of buffers reserved to store only multicast packets received from any of the ingress ports to be forwarded to at least one egress port to members of a multicast group.