Abstract: A communication system with switched hub is disclosed including a set of communication ports that transfer inbound and outbound communication frames over corresponding serial communication links. The communication ports determine a destination port for each incoming communication frame and perform interleaved transfers of the incoming communication frames to a set of virtual transmit first-in first-out (FIFO) memories that buffer communication frames for outbound transfer. The mechanism disclosed enables fast and efficient switching of the inbound frames to corresponding outbound ports.

Abstract: A method for detecting collisions between digital messages transmitted on a common cable communication system is disclosed. A transmitting station computes a cylic redundancy checking (CRC) code for the transmitted message, and stores the value of the code after N bits have been sent. N bits corresponds to the number of bits transmitted during the "collision window" of the particular system. The transmitting station monitors the receive channel and computes a CRC value for N bits of the received message. If the CRC value calculated for the received message does not match the stored CRC value for the transmitted message, a collision is assumed. If no message is received by the transmitting station after the collision window has elapsed, a collision is also assumed.