Method and system for enforcing maximum transit delay in network multiplexers

A queue of entries that efficiently tracks queued entries to allow stale entries to be recognized, the queue comprising:

• indications of the head and tail entries queued to the queue;
• a memory area in which entries are stored;
• a stale-entry field within each entry queued to the transmit queue comprising a single bit, the initial value of the stale entry field having the bit value 0;
• and
• an update routine executed at regular intervals to recognize stale entries and to update stale-entry fields of queued entries that recognizes all message descriptors having stale-entry fields containing the bit value 1 as being stale and updates all stale-entry fields containing the bit value 0 to contain the bit value 1.

A network multiplexer comprising:

• a number of communications ports, each communication port having a transceiver and a communications controller;
• a memory;
• an internal bus for transferring packets from ports to memory and from memory to ports;
• a
• a transmit queue associated with each port, each transmit queue containing a memory area that stores message descriptors that reference packets stored in memory, each message descriptor including a stale-entry field, the transmit queue efficiently tracking queued entries to allow stale entries to be recognized, the stale-entry field comprising a single bit, the initial value of the stale entry field having the bit value 0;
• and
• an update routine executed at regular intervals to recognize stale entries and to update stale-entry fields of queued entries in transmit queues associated with communications ports in the network multiplexer, the update routine recognizing all message descriptors having stale-entry fields containing the bit value 1 as being stale and updates all stale-entry fields containing the bit value 0 to contain the bit value 1.