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United States Patent u9]
Yang et al.
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US005481538A [li] Patent Number:  Date of Patent:
 FRAME REMOVAL MECHANISM FOR
TOKEN RING NETWORKS USING ONE OR
MORE START STRIP DELIMITER FRAMES
OR CIRCULATION TIME INTERVAL
 Inventors: Henry S. Yang, Andover; K. K.
Ramakrishnan, Maynard; Barry
Spinney, Wayland, all of Mass.
 Assignee: Digital Equipment Corp., Maynard, Mass.
 Appl. No.: 866,958
 Filed: Apr. 9,1992
Related U.S. Application Data
 Continuation of Ser. No. 546,618, Jun. 29,1990, abandoned, which is a continuation-in-part of Ser. No. 483,296, Feb. 20, 1990, abandoned, which is a continuation of Ser. No. 231,773, Aug. 8, 1988, abandoned.
 Int. CI.6 H04L 12/46
 U.S. CI 370/85.5; 370/85.14; 370/85.15
 Field of Search 370/85.14, 16.1,
370/85.5, 85.15, 85.13, 85.4, 94.1; 340/825.05,
 References Cited
U.S. PATENT DOCUMENTS
4,468,734 8/1984 Lanier et al 364/200
4,507,777 3/1985 Tucker etal 370/16.1
4,567,590 1/1986 Bederman 370/85.15
4,577,313 3/1986 Sy 370/85.14
4,646,232 2/1987 Chang etal 364/200
4,789,982 12/1988 Coden 370/85.5
4,932,023 6/1990 Geyer et al 370/85.5
4,941,142 7/1990 Kida 370/85.5
5,053,946 10/1991 Jain 364/200
5,142,530 8/1992 Geyer et al 370/85.5
5,224,096 6/1993 Onishi et al 370/85.5
5,235,593 8/1993 Grow et al 370/85.5
5,280,478 1/1994 Yang et al 370/85.5
5,280,582 1/1994 Yang et al 395/200
Frame processing apparatus, and a related method for its operation, for use in a station connected to a token ring network, to ensure rapid stripping of frames from the network without reference to source addresses in the frames, and in spite of the possible presence of extraneous no-owner frames on the network. The adverse effects of extraneous no-owner frames are avoided by any of three techniques. First, transmitted information frames are preceded by a start strip delimiter frame and followed by an end strip delimiter frame. The process strips all incoming frames (except tokens and ring initialization frames, which are specially handled), but does not count the stripped frames until the start strip delimiter frame is detected. Therefore, extraneous frames preceding the transmitted information frames will be stripped but not counted, and all of the transmitted frames will be stripped. In another approach, an estimated stripping time is used to terminate stripping. Frame counters are not then needed and extraneous frames will be stripped prior to the desired information frames. A third approach is to preset the transmitted frame count to some selected value, so that more frames will be stripped than were transmitted. Thus, preceding extraneous frames will be stripped, but the end strip delimiter will still terminate stripping and preclude overs tripping.
53 Claims, 15 Drawing Sheets
May 20,1988, Modifications to the IEEE 802.5 Standard to
Include Early Token Release, by Jacalyn Winkler, 6 pages.
Dec. 1,1987 Changes to the IEEE 802.5 Standard to Include
Early Token Release, 3 pages.
Nov. 17, 1986, Enhancement to the Token Ring Protocol:
Early Token Release, 5 numbered pages and 8 Figs.
1985, ANSI/IEEE Standard 802.5—1985, 89 + pages.
National Telecommunications Conference, vol. 1, Dec.
1981, New Orleans, La., US. W Bux et al. "A Reliable Token-Ring System for Local Area Communication" pp. A2.2.1-A2.2.1.
EP 91 30 5330 European Search Report, Jan. 15, 1992.
Data Communications, vol. 13, No. 9, Aug. 1984, New York, N.Y. US, pp. 125-139; J. Bartik; "IBM's token ring: Have the pieces finally come together?", see p. 131, left-hand column, lines 3-13, see p. 135, left-hand column, line 17-p. 136, left-hand column, line 10.