Self-routing packet switching network with intrastage packet communication

• US 4,661,947 A
• Filed: 09/26/1984
• Issued: 04/28/1987
• Est. Priority Date: 09/26/1984
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: Montgomery, Warren A., Lea, Chin-Tau A.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Rokoff, Kenneth I.
• Application Number:
  US06/654,763
• Time in Patent Office: 944 Days
• Field of Search: 370/60, 370/94, 370/58, 370/16, 370/54
• US Class Current: 370/355
• CPC Class Codes: H04L 49/15 Interconnection of switching modules
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3009 Header conversion, routing tables or routing tags

Abstract

A communication method and packet switching network in which self-routing packets are communicated through the network by intra-communication of the packets within stages of the network as well as inter-communication of the packets among stages. The stages each having a plurality of pairs of switch nodes with each pair having an intra-node link between the pair of nodes. Each of the switch nodes comprises input controllers and output controllers. The input controller of a node is responsive to the receipt of a packet for interrogating the address field of the packet to determine the destination of the packet. The input control on the basis of the destination determination commmunicates the packet towards the destination via either an inter-stage link or an intra-node link on the basis of availability of the links and an internal control circuit. If a packet is transmitted via an intra-node link to the paired node the latter then transmits the packet via its output controller to the next stage via an inter-stage link. If both the intra-node link and the inter-stage link are available, the internal control circuit then determines which link should be utilized in communicating the packet. The internal destination circuit performs this designating function on the basis of a random number generator.

Claims

1. A packet switching network for communicating packets each comprising routing information from network input ports to network output ports, said network comprising:

a plurality of stages each comprising a plurality of switch nodes;

inter-node and intra-node links connecting one of said switch nodes of one of said stages to a set of switch nodes in another stage;

each of said intra-node links intra-connecting said one of said switch nodes to a switch node of said other stage via another switch node of said one of said stages and another inter-node link from said other switch node of said one of said stages to said switch node of said other one of said stages;

said one of said switch nodes comprising means responsive the routing information of one of said packets for selecting a subset of said inter-node and intra-node links;

means for generating signals to designate one of said subset of said inter-node and intra-node links for communication of said one of said packets; and

means responsive to said signals for routing said one of said packets to one of said set of said switch nodes of said other one of said stages.

2. The system of claim 1 wherein said routing means comprises means for sending a packet communication request signal to the switch node of said one of said stages connected to the designated one of said intra-node links:

and

said connected switch node comprises means responsive to said packet communication request signal for supplying a signal to said one of said switch nodes of said stage to signify the packet communication availability of said connected switch node.

3. The system of claim 2 wherein said connected switch node interconnected via one of said inter-node links to another node in said other stage comprising buffer means for storing said one of said packets;

and

said supplying means comprises means for transmitting said packet communication availability signal upon said buffer means having present capacity to store said one of said packets.

4. The system of claim 3 wherein said supplying means further comprises means for transmitting a packet communication unavailability signal upon the absence of present capacity in said buffer means for storing said one of said packets;

and

said routing means further comprises means responsive to said packet communication unavailability signal for communicating said one of said packets to another one of said switch nodes connected to said subset of intra-node and inter-node links.

5. The system of claim 4 wherein said generating means comprises a random number generator to generate the designating signals.

6. A packet switching network for communicating packets each comprising address routing information from network input ports to network output ports, said network comprising:

a plurality of switching stages;

a plurality of inter-node links interconnecting said stages;

each of said stages comprising a plurality of switch nodes and intra-node links connecting subsets of said plurality of switch nodes;

one of said switch nodes of one of said subsets of one of said stages responsive to the address routing information of one of said packets for communicating said one of said packets to a switch node of another one of said stages via a second one of said switch nodes of said one of said subsets and one of said intra-node links; and

one of said switch nodes of one of said stages responsive to address information of another one of said packets for communicating said other one of said packets to another switch node of said other one of said stages via one of said inter-node links.

7. The system of claim 6 wherein said one of said switch nodes of said one of said stages further comprises means responsive to said other one of said switch node of said other one of said stages being busy for communicating said other one of said packets to a third one of said switch nodes of said other one of said stages via a second one of said switch nodes of said one of said stages and said intra-node link.

8. The system of claim 7 wherein said switch node of said one of said stages further comprises means for buffering said other one of said packets for communication to said other one of said stages.

9. A packet switching network for communicating packets each comprising address routing information from network input ports to network output ports, said network comprising:

a plurality of switching stages;

a plurality of inter-node links interconnecting said stages;

each of said stages comprising pairs of switching nodes;

a plurality of sets of intra-node links each connecting an individual pair of said switching nodes;

one of said nodes of one of said pairs comprising means for controlling an input set of said inter-node links connected to a preceding stage;

means for controlling an output set of said inter-node links connected to a next sequential stage;

said input control means comprises means for controlling the set of intra-node links connected to the other one of said one of said pair;

said input control means further comprises means responsive to the address information of one of said packets for selecting one inter-node link of the output set of said inter-node links and one intra-node link of said set of intra-node links connected to said input control means;

said input control means further comprises means for generating a first set of signals designating intranode links and a second set of signals designating internode links; and

said input control means further comprises first means responsive to said first set of signals and said selecting means for communicating one of said packets to the selected intra-node link of said intra-node links and further comprises second means responsive to said second set of signals and said selecting means for communicating said packet to the selected inter-node link of said set of inter-node links.

10. The network of claim 9 wherein said designating means comprises a random number generator.

11. The network of claim 9 wherein said input control means further comprises means for transmitting a communication request in response to said selecting means and said second set of signals via said selected intranode link to another switch node of the next sequential stage connected to said selected inter-node link;

said other switch node comprises another input control means responsive to said communication request for generating a communication available signal upon said other input control means being idle;

the first communicating means comprises means responsive to said availability signal for enabling the communication of said packet.

12. The network of claim 11 wherein said other input control means comprises variable buffering means for variably storing packets and means responsive to present capacity of said variable buffering means to store said packet for enabling said communication availability signal.

13. The network of claim 9 wherein the second communicating means comprises:

means responsive to said first set of signals and said selecting means for transmitting a communication request signal via said selected intra-node link; and

said output means comprises means responsive to said communication request for generating a communication availability signal upon said output means having capacity for transmitting said packet to said next sequential stage.

14. A method of switching packets through a packet switching network comprising a plurality of stages each having a plurality of switch nodes with inter-node and intra-node links connecting one of said nodes of one of said stages to a switch node in another stage and each of said intra-node links intra-connecting said one of said switch nodes to a switch node of said other stage via another switch node of said one of said stages and another inter-node link, and comprising the steps of

selecting a subset of said inter-node and intra-links by said one of said switch nodes responding to routing information of one of said packets;

designating one of said subset of said internode and intra-node links for communication of said one of said packets; and

routing said one of said packets to one of said set of said switch nodes of said other one of said stages via the designated link.

15. The method of claim 14 wherein said routing step further comprises the step of

sending a packet communication request to the node of said one of said stages connected to the designated one of said intra-node links;

and

supplying a signal to said one of said switch nodes of said stage to signify the packet communication availability of the connected switch node.

16. The invention of claim 15 wherein said connected switch node having a buffering means for storing said one of said packets and said routing step further comprises the step of determining the present capacity of said buffer means to store said one of said packets prior to the transmission of said packet communication availability signal.

17. The invention of claim 16 wherein said determining step further comprises the steps of

communicating a packet communication unavailability signal upon the absence of present capacity in said buffer means for storing said one of said packets;

and

communicating said one of said packets to another one of said switch nodes connected to said subset of intra-node and inter-node links in response to receipt of said packet communication unavailability signal.

18. The invention of claim 17 wherein said designating step comprises the step of randomly generating signals for use in the designation of the one of said links.

19. A packet switching network for communicating packets, each packet comprising routing information from network input ports to network output ports, said network comprising:

a plurality of stages each comprising a plurality of switch nodes;

inter-node links connecting one of said switch nodes of said stages to a set of switch nodes in another stage;

intra-node links interconnecting switch nodes of the same stage;

each of said intra-node links intra-connecting said one of said switch nodes of said one of said stages to a switch node of said other stage via another switch node of said one of said stages and another inter-node link from said other switch node of said one of said stages to said switch node of said other one of said stages;

said one of said switch nodes comprises;

output control means inter-connected by said inter-node links to said set of switch nodes in said other stage;

input control means responsive to said routing information of one of said packets for selecting a subset of said inter-node and intra-node links;

said input control means comprises;

controller means for generating signals to designate one of said subset of said inter-node and intra-node links for transmission of said one of said packets; and

multiplexer means responsive to the generated signals for routing said one of said packets to one of said set of said switch nodes of said other one of said stages.

20. The system of claim 19 wherein said controller means comprises means for sending a packet communication request signal to said other switch node of said one of said stages connected to the designated one of said intra-node links;

and

said other switch node comprises another output control means responsive to said packet communication request signal for supplying a signal to said one of said switch nodes of said stage to signifying the packet communication availability of the connected switch node.

21. The system of claim 20 wherein said connected switch node interconnected via said one of said inter-node links to another node in said other stage and the latter node comprises buffer means for storing said one of said packets;

and

said other output control means transmits said packet communication availability signal upon said buffer means having present capacity to store said one of said packets.

22. The system of claim 21 wherein

said other output control means further comprises means for transmitting a packet communication availability signal upon the absence of present capacity in said buffer means for storing said one of said packets;

and

said controller means further responsive to said packet communication unavailability signal for communicating said one of said packets to another one of said switch nodes connected to said subset of intra-node and inter-node links.

23. The system of claim 22 wherein said input control means comprises a random number generator to generate said designating signals.

24. A method of switching packets through a packet switching network comprising a plurality of stages each having a plurality of switch nodes with inter-node and intra-node links connecting one of said nodes of one of said stages to a switch node in another stage and each of said intra-node links intra-connecting said one of said switch nodes to a switch node of said other stage via another switch node of said one of said stages and another inter-node link, and comprises the steps of

selecting a subset of said inter-node and intra-links by said one of said switch nodes responding to routing information of one of said packets;

designating one of said subset of said inter-node and intra-node links for communication of said one of said packets; and

routing said one of said packets to one of said set of said switch nodes of said other one of said stages.

25. The method of claim 24 wherein said routing step further comprises the steps of

sending a packet communication request to said node of said other one of said stages connected to said designated one of said intra-node links;

and

supplying a signal to said one of said switch nodes of said stage to signify the packet communication availability of the connected switch node.

26. The invention of claim 25 wherein said connected switch node having a buffering means for storing said one of said packets and said routing step further comprises the step of determining the present capacity of said buffer means to store said one of said packets prior to the transmission of said packet communication availability signal.

27. The invention of claim 26 wherein said determining step further comprises the steps of communicating a packet communication unavailability signal upon the absence of present capacity in said buffer means for storing said one of said packets;

and

communicating said one of said packets to another one of said switch nodes connected to said subset of intra-node and inter-node links in response to receipt of said packet communication unavailability signal.

28. The invention of claim 27 wherein said designating step comprises the step of randomly generating signals for use in the designation of said one of said subsets.