Importance

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Abstract

A technique for prioritizing accesses to a communication bus by data-communication ports in a multi-port bridge for a local area network. The bridge includes a plurality of ports interconnected by the bus. The bus includes signal lines dedicated to communicating commands, signal lines dedicated to communicating data, and several signal lines having special purposes. For example, two signal lines, are preferably dedicated to initiating different types of access to the bus, each having a respective priority. The ports are of two types (e.g. 100 Mbps or 10 Mbps data rates), each having a respective priority. A bus controller monitors the type of access to the bus attempted and the type of ports attempting access and grants access to the bus according to an appropriate priority. Ports of a like type which attempt a like type of access to the communication bus are granted access to the bus according to an assigned relative order, wherein the assigned relative order repeats and wherein a port last granted access to the communication bus has a lowest priority and a port adjacent in the assigned relative order to the last port granted access to the communication bus has a highest priority and remaining ports have ascending intermediate levels of priority according to the assigned relative order. Logic utilized makes a determination of which port is to be granted access to the bus in the appropriate priority with a minimum of delay.

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First Claim