International Business Machines Corporation

Robert William Bartoldus

Brian Mitchell Bass

Kenneth Harvey Potter, Jr

Edward Joel Rovner

Edward Stanley Suffern

James William Feeney

Scott Nellenbach

William Craig Troop

Timothy Droz

Jorge R Rodriquez

A method and system for adjusting a message preamble on a shared bus, wherein the message preamble includes N synchronization characters, and each of the synchronization characters is separated in time by a random delay interval. First, an activity status is determined for the shared bus in terms of the number of stations that are currently active on the bus. The number of synchronization characters is then adjusted according to the bus activity status. The activity status is also utilized as a dynamic adjustment parameter for the random delay interval that includes a fixed delay term, D, added to a randomly determined delay increment, d. In this manner the message preamble specification is optimized according to real-time network demands, such that latency and data collisions are minimized.

Dynamic preamble configuration on a shared bus

A LAN interconnect device includes a plurality of Frame Processing Units (FPUs) for coupling each port of the device to a switch fabric. Each one of the Frame Processing Units includes an input section with input logic which prepares LS Headers and appends each one to a block of the frame as the block is forwarded to the switch fabric. The FPU, also, includes an output section with copy logic for copying and assembling frames to be forwarded to devices connected to the port. The copy decision is based upon the LS Header and configuration information in the port.

LAN frame copy decision for LAN switches

A LAN switching system includes an Address Match Control line which can be set (activated) and is monitored by each port adapter card. If a port adapter card recognizes an address on the switch fabric, the adapter card copies the frame with the address and activates the Address match Control line. The set Address Match Control line causes the remaining port adapter cards to stop searching for a match. If the Address Match Control line is not set, the frame can be copied by all port adapters which are configured to do so.

LAN switch with distributed copy function

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Robert William Bartoldus