(54) METHOD AND APPARATUS FOR
MINIMIZING CONTENTION LOSSES IN
NETWORKS
(75) Inventor: Howard Thomas Olnowich, Endwell, NY (US)
(73) Assignee: International Business Machines Corporation, Armonk, NY (US)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.
(21) Appl. No.: 09/428,636
(22) Filed: Oct. 27, 1999
Related U.S. Application Data
(62) Division of application No. 08/883,487, filed on Jun. 26, 1997.
(51) Int. CI.7 H04B 3/38; H04L 12/50
(52) U.S. CI 370/388; 370/411; 340/826;
379/220
(58) Field of Search 370/386, 388,
370/411, 351, 367, 228, 462; 340/825.01, 825.02, 826, 827, 825.05, 825.79; 379/219, 220, 221, 271, 273
(56) References Cited
U.S. PATENT DOCUMENTS
4,663,620 * 5/1987 Paul et al 370/462
4,991,168 2/1991 Richards 340/825.8
4,991,203 2/1991 Kakizawa 379/209
5,099,509 3/1992 Morganstein et al 379/84
5,099,511 3/1992 Matsumoto 379/198
5,345,229 9/1994 Olnowich et al 370/360
5,404,537 * 4/1995 Olnowich et al 370/388
5,444,705 8/1995 Olnowich et al 370/388
5,451,936 * 9/1995 Yang et al 340/826
5,654,695 8/1997 Olnowich et al. .
5,754,120 * 5/1998 Argentati 340/825.06
5,835,024 11/1998 Olnowich et al 370/388
5,933,428 8/1999 Olnowich .
5,945,922 * 8/1999 Gao et al 340/825.8
FOREIGN PATENT DOCUMENTS
2-237335 9/1990 (JP) H04L/012/02
5-344146 12/1993 (JP) H04L/012/48
OTHER PUBLICATIONS
NEC Corp., Camp—on system for data communication between terminal and computer. WPAT AN 90-331157/44 JP J02237335-A Sep. 19, 1990. No abstract. NEC Corp., Camp-on system for stored programme electronic swithcing. WPAT AN 88-170557/25 JP J63107264-A May 12, 1988. No abstract.
* cited by examiner
Primary Examiner—Alpus H. Hsu
Assistant Examiner—Afsar M. Qureshi
(74) Attorney, Agent, or Firm—Shelley M. Beckstrand
(57) ABSTRACT
Contention losses are minimized in path searching, circuitswitched networks by adding intelligence to the last stage of the network. A count of number of bytes remaining to be transferred in each active message is maintained in real time for each output port of the network. If contention arises at the last stage switch being requested in camp-on mode to make a connection to a busy output port, the switch checks the bytes remaining count and responds differently depending on how the bytes remaining count compares to a preset threshold register. If the count remaining is below the threshold, the last stage switch accepts the camp-on request, because the desired output port will be available shortly. If the count remaining is above the threshold or below the threshold but another user is camped-on, the switch rejects the camp-on request to the last stage, because the desired output port will not be available shortly. In this case further path searching would be meaningless. Adifferent message to a different destination (output port) is tried, and later the contended message is retried.
21 Claims, 38 Drawing Sheets
