US 6,477,171 B1Granted

Method and system for negotiation of the highest common link rate among nodes of a fibre channel arbitrated loop

AssigneeAgilent Technologies, Inc.

InventorsMatthew Paul Wakeley, George McDavid

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Abstract

A method and system for automatic negotiation of maximal shared data transmission and reception rates by fibre channel nodes in a fibre channel arbitrated loop. An auto-speed-negotiation function is included in the fibre channel arbitrated loop initialization procedure. A fibre channel node undergoing initialization turns off its transmitter in order to elicit a loss of synchronization condition in the next fibre channel node of the arbitrated loop. Upon detection of loss of synchronization, each subsequent fibre channel arbitrated loop node invokes the auto-speed-negotiation function. The fibre channel node then turns its transmitter back on at the highest possible data transmission rate, sets the data reception rate of the fibre channel node's receiver to the lowest possible data reception rate, and then waits to detect word synchronization by the receiver. If word synchronization is not detected within a reasonable period of time, the fibre channel node changes the data reception rate of the fibre channel node's receiver and again waits to detect word synchronization. Once word synchronization is detected, the fibre channel node again invokes the auto-speed-negotiation function if its current data transmission rate is not equal to its current data reception rate after setting its current data transmission rate equal to its current data reception rate.

Claims10

Dependent claims

A method for conducting automated transmission and reception speed negotiation within a fibre channel port of a fibre channel node in a fibre channel arbitrated loop, the method comprising:

turning off a transmitter of a transceiver component of the fibre channel port;
waiting for a first period of time;
turning on the transmitter of the transceiver component of the fibre channel port and setting the transmitter's data transmission rate to a high data transmission rate;
setting a data reception rate of a receiver of the transceiver component to a low data reception rate;
iteratively
waiting to detect word synchronization by the receiver of the transceiver component, and, when word synchronization is not detected within a second period of time, setting the data reception rate of the receiver of the transceiver component to a different data reception rate
until word synchronization is detected;
determining whether the data transmission rate is equal to the data reception rate immediately following word synchronization, and, if the data transmission rate is not equal to the data reception rate immediately following word synchronization,
turning off the transmitter of the transceiver component of the fibre channel port;
waiting for a third period of time;
and
turning on the transmitter of the transceiver component of the fibre channel port and setting the data transmission rate of the transmitter to the data reception rate of the receiver of the transceiver component.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/452,618Filed 1 Dec 1999
Granted: 5 Nov 2002
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04L 12/42
Characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]: loop networks
H04L 25/0262
Details ; arrangements for supplying electrical power along data transmission lines: arrangements for detecting the data rate of an incoming signal
H04J 3/0658
Clock or time synchronisation among nodes; Internode synchronisation: clock or time synchronisation among packet nodes
H04L 7/04
Arrangements for synchronising receiver with transmitter: speed or phase control by synchronisation signals