Multiplex communications – Wide area network – Packet switching
Patent
1995-01-18
1996-07-23
Kizou, Hassan
Multiplex communications
Wide area network
Packet switching
370 84, 370 942, 370108, 370112, 375260, H04J 306, H04J 326, H04L 1256, H04L 2514
Patent
active
055397409
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is directed to a method for forwarding a message cell stream via a plurality of parallel trunks, whereby an asynchronous transfer method, rate of an individual trunk, distributed onto the plurality of trunks and forwarded.
Conditioned by technology, the transmission bit rate on the individual, physical transmission links of a transmission system is limited by the processing speed of the transmission elements such as, for example, trunks or switching elements that are employed. When a message cell stream whose transport bit rate exceeds the transmission bit rate of an individual, physical transmission link is to be transmitted, then it can be transmitted via a plurality of parallel, physical transmission links.
IEEE International Conference on Communications ICC '90, Conference Record, 16-19 April 1990, Atlanta, U.S.A., vol. 2, pp. 771-777 discloses a transmission system wherein a stream of packets carrying useful data is forwarded via a group of parallel trunks. Successive message cells are thereby cyclically distributed onto the group of trunks and are forwarded during the same time slot. Due to different lengths, different temperature or different line lengths of the trunks in the groups of trunks or due to fluctuations in the clock frequencies given plesiochronic switching systems, non-directional deviations in running time of the packets can occur. Due to the deviations in running time, errors in the sequence of the packets can occur upon reception of the packets, as shall be set forth in greater detail later.
SUMMARY OF THE INVENTION
The invention is based on the problem of specifying a method that allows a forwarding of message cells of a message cell stream via a plurality of parallel trunks while assuring the sequence of the message cells--even given the occurrence of non-directional deviations in running time on the individual trunks.
In the method initially cited, the problem is resolved in that the message cells, whereby, given the cyclical interrogation of successive trunks, cells are forwarded, and interrogation cycles is shorter than the duration of the forwarding of a message cell.
Based on the criterion of the need for transmission capacity for a message cell stream, the method of the invention enables a flexible offerability of a plurality of trunks, whereby the sequence of the message cells of the message cell stream is strictly observed at the transfer to a following transmission equipment. The beginning of an interrogation cycle is thereby uncorrelated with the transmission time slots on the trunks.
A development of the method of the invention provides that an arrival character is set at the arrival of a message cell from a trunk in a reception means, and the arrival character that has been set is reset when the trunk is interrogated. What this measure assures is that every message cell is transferred only once into a reception equipment.
A further development of the method of the invention provides that the designations of message cells that are to be forwarded onto a bundle of successive trunks are entered into the queue belonging to the trunk whose designation derives by masking the least significant binary character of the binarily presented queue designation. This measure provides an especially simple selection of a queue for bundle sizes whose plurality of trunks can be presented by a whole exponent of the mantissa 2.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several Figures of which like reference numerals identify like elements, and in which:
FIG. 1 an illustration of the inventive forwarding of successive message cells of a message cell stream via a bundle of four trunks;
FIG. 2 a schematic illustration of the interconnection of t
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Electronics and Communications in Japan, Part 1, vol. 68, No. 9, 1985, "Analysis on a Multilink Packet Transmission System with Random Allocation", Toshihiro Nishizono et al., pp. 98-104.
IEEE International Conference on Communication ICC 1990, "A 3-Stage Interconnection Structure for Very Large Packet Switches", Soung C. Liew et al, pp. 771-777.
IEEE Journal on Selected Areas in Communications, vol. 9, No. 8, Oct. 1991, "A Scalable ATM Switching System Architecture", Wolfgang Fischer, et al, pp. 1299-1307.
Kizou Hassan
Siemens Aktiengesellschaft
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