United States Patent   Patent Number: 4,703,475
Dretzka et al.  Date of Patent: Oct. 27,1987
 DATA COMMUNICATION METHOD AND APPARATUS USING MULTIPLE PHYSICAL DATA LINKS
 Inventors: Ellen E. Dretzka, Naperville; Zoe S.
Quan, Chicago; Philip A. Schreiner,
Naperville, all of 111.
 Assignee: American Telephone and Telegraph Company AT&T Bell Laboratories, Murray Hill, N.J.
 Appl. No.: 805,304
 Filed: Dec. 4,1985
 Int. Q.4 H04Q 11/04; H04J 3/24
 U.S. a 370/60; 370/94
 Field of Search 370/60, 94, 110.1, 99
 References Cited
U.S. PATENT DOCUMENTS
4,516,238 5/1985 Huang et al 370/94
4,527,267 7/1985 Cohen 370/94
4,550,404 10/1985 Chodrow et al 370/110
4,569,042 2/1986 Larson 370/60
4,617,657 10/1986 Drynan et al 370/94
CCITT Recommendation X.25 (1984) "Interface Between Data Terminal Equipment (DTE) and Data Circuit-Terminating Equipment (DCE) for Terminals Operating in the Packer Mode on Public Data Networks", See Section 2.5, pp. 39-49.
CCITT Recommendation X.75 (1984) "Terminal and Transmit Call Control Procedures and Data Transfer
System on International Circuits Between Packet-Switched Data Networks", See Section 2.5, pp. 164-176. A. S. Tanenbaum, "Virtual Circuits And Datagrams", Computer Networks, Prentice-Hall, Inc., 1981, See Section 5.1, pp. 187-196.
Primary Examiner—Douglas W. Olms
Assistant Examiner—Frank M. Scutch, III
Attorney, Agent, or Firm—Ross T. Watland
A multi-link interprocessor communication protocol that allows a pair of processors to increase the speed of their communication by using multiple physical links in parallel. When a message is sent from one processor to another, the message is packetized into smaller segments and loaded onto the available physical links according to a simple algorithm. The individual packets are received at the other end, their accurate transmission verified, and the received packets are then reassembled in the proper order. Packets of one or more messages to the same destination can go over the same physical link, or over different physical links; that is, there is no association of any message to any particular physical communication link. Packets received out of order on a per logical channel basis are stored until a correct sequence of packets is received after which their transmission to the message destination is effected. The reordering of packets is accomplished using a multi-link header advantageously comprising only a single byte.
32 Claims, 20 Drawing Figures