Method and apparatus for managing the flow of data within a switching device

A switching device comprising:

• a backplane;
• a bus;
• a master control process coupled to the backplane and the bus, the master control process including a memory to store routing information;
• and
• a plurality of interface cards including a first interface card that comprises a local memory to store a portion of the routing information already stored in the memory of the master control process upon receiving a packet that includes a destination address about which no routing information is currently stored, the portion of the routing information including a destination tag including a multicast field and a port field that specifies a destination port associated with one of the plurality of interface cards for receipt of information associated with the packet when the multicast field specifies that the packet is being routed in accordance with a unicast transmission.

A switching device comprising:

• a backplane;
• a bus;
• a master control process coupled to the backplane and the bus, the master control process including a memory to store routing information;
• and
• a plurality of interface cards coupled to the backplane and the bus, at least a first interface card of the plurality of interface cards comprises a local memory to store a portion of the routing information already stored in the memory of the master control process upon receiving a packet that includes a destination address about which no routing information is currently stored, the portion of the routing information including a destination tag to identify whether or not the packet is routed to a destination port associated with one of the plurality of interface cards.

Implemented within a switching device including a backplane, a bus, a master control process adapted for coupling to the backplane and the bus and including a memory to store routing information and a plurality of interface cards, a first interface card of the plurality of interface cards comprising:

• a memory controller coupled to the bus;
• and
• a local memory to store therein a destination tag for specifying a destination of an incoming packet received by the first interface card, the destination tag comprises;
• a multicast field to enable a multicast transfer of the packet to multiple ports on the plurality of interface cards, and
• a port field to enable point-to-point forwarding of the packet when the multicast transfer is not being performed by the first interface card, the port field specifying a first port of at least one of the plurality of interface cards.

A switching device comprising:

• a backplane;
• a bus;
• a master control process coupled to the backplane and the bus, the master control process including a memory to store routing information;
• and
• a plurality of interface cards coupled to the backplane and the bus, at least a first interface card of the plurality of interface cards comprises a local memory to store a portion of the routing information already stored in the memory of the master control process upon receiving a packet that includes a destination address about which no routing information is currently stored, the portion of the routing information including a destination tag that comprises at least a multicast field to indicate whether or not the packet is to be routed to at least two ports on the plurality of interface cards.

A method for routing data over a switching device including (i) a backplane, (ii) a bus, (iii) a master control process adapted for coupling to the backplane and the bus and including a central table to store routing information, and (iv) a plurality of interface cards, the method comprising:

• determining whether or not an entry associated with a destination address contained in an incoming cell resides in a local table contained in a memory of a first interface card of the plurality of interface cards;
• if the local table does not contain the entry associated with the destination address, moving a portion of the routing information from an entry associated with the destination address residing in the central table over the bus;
• loading the portion of the routing information within an entry of the local table;
• and
• using the portion of the routing information to route the cell to at least one port on the plurality of interface cards.