Apparatus and method for inter-processor communications in a multiprocessor routing node

A communication network comprising a plurality of routers that communicate data packets to one another and to interfacing external devices, each of said plurality of routers comprising:

• a switch fabric;
• and
• R routing nodes coupled to said switch fabric, each of said R routing nodes capable of exchanging data packets with said external devices and with other ones of said R routing nodes via said switch fabric, wherein a first of said R routing nodes comprises:
• an inbound network processor comprising a first plurality of microengines capable of forwarding incoming data packets from external ports to said switch fabric;
• an outbound network processor comprising a second plurality of microengines capable of forwarding outgoing data packets from said switch fabric to said external ports;
• and
• a plurality of registers for transferring messages between said first plurality of microengines and said second plurality of microengines.

For use in a routing node comprising 1) an inbound network processor comprising a first plurality of microengines that forward incoming data packets from external ports to a switch fabric and 2) an outbound network processor comprising a second plurality of microengines that forward outgoing data packets from the switch fabric to the external ports, a method of transferring messages between the first plurality of microengines and the second plurality of microengines comprising the steps of:

• writing a first message from any one of the second plurality of microengines to a first dedicated mailbox register associated with a first one of the first plurality of microengines;
• setting a first full flag associated with the first dedicated mailbox register;
• reading the first message from the first dedicated mailbox register into the first one of the first plurality of microengines;
• and
• clearing the first full flag.