Early availability of forwarding control information

A method of steering a packet through a packet forwarding device, the method comprising the steps of:

• receiving packet data at an ingress port interface;
• fragmenting the packet data into fixed-length cells;
• and
• queuing each of the fixed-length cells for transmission from an egress port interface by
• inserting forwarding control information into the cell,
• buffering the cell in an intermediate device, and
• adding the cells to an output queue associated with the egress port interface
• by
• accessing the forwarding control information from the cell via a separate and independent control interface of the intermediate device,
• determining with which output queue to associate the cell based upon the forwarding control information, and
• transferring the cell into a memory via a data interface of the intermediate device.

A packet forwarding device comprising:

• a plurality of port interface devices (PIDs) each configured to fragment packets into a plurality of cells, each of the plurality of cells containing cell data, a portion of which serves as forwarding control information, wherein one or more of the plurality of PIDs comprise quad-port interface devices (QUIDs);
• memory access circuitry coupled to each of the PIDs to receive cell data, the memory access circuitry including
• a data interface that outputs the cell data, and
• an independent control interface that outputs the forwarding control information;
• a memory coupled to the data interface of the memory access circuitry to temporarily store the cell data;
• and
• a management device coupled to the independent control interface of the memory access circuitry to receive the forwarding control information, the management device using the forwarding control information to organize cells into one or more groups.

A switch comprising:

• an input/output (I/O) interface configured to add forwarding control information to inbound packet data;
• and
• a switch core coupled to the I/O interface to receive data including the forwarding control information and the inbound packet data, the switch core including
• memory access circuitry configured to output the data received from the I/O interface onto a data path, the memory access circuitry further configured to concurrently output the forwarding control information onto a separate control path as it outputs the data onto the data path,
• a memory coupled to the data path, the memory temporarily storing the data received from the I/O interface, and
• a management device coupled to the separate control path, the management device maintaining a plurality of output queues and associating the data received from the I/O interface with one of the plurality of output queues based upon the data's forwarding control information.

A method of forwarding data through a network device, the method comprising the steps of:

• receiving a packet at a first port interface of a network device;
• the first port interface transferring a cell to an intermediate device, the first cell comprising data from the packet and forwarding control information associated with the packet,
• the intermediate device outputting the cell to a memory via a data path and outputting the forwarding control information to a queue managing device via a separate and independent control path;
• the queue managing device determining an output queue with which to associate the cell based upon the forwarding control information;
• and
• transferring the cell to a second port interface device associated with the output queue, wherein the forwarding control information includes information identifying the second port interface.