Polling response selection using request monitoring in a network switch apparatus

A switch node, comprising;

• a plurality of port modules that each send packets to a switch and receive packets from the switch;
• and
• a first port module of the plurality of port modules, the first port module further comprising a plurality of input buffers and an arbiter, the arbiter;
• a) being coupled to the plurality of input buffers, each input buffer of the plurality input buffers to hold a packet prior to its being sent from the first port module through the switch to one of the plurality of port modules other than the first port module, wherein, packets destined to different port modules are held in different input buffers;
• b) being coupled to a bus, the bus being coupled to each of the plurality of port modules other than the first port module;
• c) to detect from the bus which of the plurality of port modules other than the first port module is a destination port module for one or more packets waiting to be sent to the switch;
• d) to delay transmission of a request to send a packet held in one of the input buffers, if, the arbiter determines that the particular port module to which the held packet is to be sent will be unable to receive it.

An arbiter that interfaces to a plurality of input buffers and a bus, the plurality of input buffers and the arbiter being part of a port module that sends packets to an asymmetric switch module and receives packets from the asymmetric switch module, the arbiter comprising:

• 1) means for monitoring the bus for requests made to the asymmetric switch module, each monitored request being a request to send a packet through the asymmetric switch module to any of a plurality of other port modules, wherein, each port module amongst the plurality of other port modules is also coupled to the bus;
• and
• 2) means for:
• a) determining which of the plurality of port modules have at least one available transmission channel through the asymmetric switch module;
• and
• b) for allowing a request for a packet to be sent to the asymmetric switch module from only one of the input buffers if a port module, from amongst the plurality of port modules, that corresponds to a destination port module of the packet has at least one available transmission channel to receive the packet from the asymmetric switch module.