Patent Number: 6,170,022

Title: Method and system for monitoring and controlling data flow in a network congestion state by changing each calculated pause time by a random amount

Abstract: Flow control is implemented at a given node in a network of LAN switches by having the node monitor the occupancy levels of buffers or queues. When a buffer is found to be occupied or filled beyond a predetermined threshold level, a pause command is generated for the source currently supplying traffic to the buffer. A pause time PT is calculated using an equation which takes into account: the transmission rate of the identified source, the transmission rate of the output link servicing the congested buffer and queue length that can be occupied without a congestion condition being declared. To reduce the chance that queue lengths will "oscillate" about their threshold point due to multiple sources resuming transmission at the same time, each calculated pause time is adjusted to a randomly selected value PT(ran) falling within a range of PT.+-.kPT where k may be on the order of fifty percent.

Inventors: Linville; John Walter (Durham, NC), Makrucki; Brad Alan (Durham, NC), Suffern; Edward Stanley (Chapel Hill, NC), Warren; Jeffrey Robert (Apex, NC)

Assignee: International Business Machines Corporation

International Classification: H04L 12/56 (20060101); G06F 013/00 (); G06F 013/14 (); G06F 013/372 (); G06F 015/00 (); G06F 015/173 ()

Expiration Date: 01/02/2018