Multi-rate synchronous virtual circuit network for voice and data communications

• US 4,763,319 A
• Filed: 05/19/1986
• Issued: 08/09/1988
• Est. Priority Date: 05/19/1986
• Status: Expired due to Fees

• Current Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Rozenblit, Moshe
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Marcelo, Melvin
• Application Number:
  US06/864,782
• Time in Patent Office: 813 Days
• Field of Search: 370/79, 370/83, 370/84, 370/89, 370/95, 370/60, 370/94
• US Class Current: 370/397
• CPC Class Codes: H04L 12/64 Hybrid switching systems

Abstract

A transmission network for enabling communication between a multiplicity of user stations is disclosed. The network can handle a wide variety of traffic types ranging from the continuous transmission of batch data to the bursty transmission of voice and interactive data. The network comprises an array of switches which are connected by trunk groups. Communication between any pair of user stations is achieved by means of a virtual circuit which passes through one or more of the switches. Frames of data are synchronously transmitted between the switches. Variable bit rate capability is achieved by allocating different numbers of slots in each frame to different virtual circuits.

Claims

1. A synchronous virtual circuit communications network capable of supporting multiple bit rate communications between pairs of user stations, said network comprising an array of interconnected switching nodes,

each of said virtual circuits connecting a pair of user stations passing through one or more switching nodes in said network,

each of said switching nodes being adapted to synchronously exchange frames of data with neighboring switching nodes, said frames being divided into slots,

the slots in each of said frames exchanged between a given pair of said switching nodes being allocated among the virtual circuits passing through said pair of switching nodes, virtual circuits having different bit rates being allocated different numbers of slots in each frame,

each of said switching nodes including means for interpreting incoming slots to determine to which virtual circuit each of said incoming slots belong, and means for allocating outgoing slots to virtual circuits requiring such slots and for deallocating slots from virtual circuits no longer requiring slots.

2. A synchronous virtual circuit communications network capable of supporting multiple bit rate communications between pairs of user stations, said network comprising an array of interconnected switching nodes,

each of said virtual circuits connecting a pair of user stations passing through one or more switching nodes in said network,

each of said switching nodes being adapted to synchronously exchange frames of data with neighboring switching nodes, said frames being divided into slots,

the slots in each of said frames exchanged between a given pair of said switching nodes being allocated among the virtual circuits passing through said pair of switching nodes, virtual circuits having different bit rates being allocated different numbers of slots in each frame,

each of said switching nodes including means for interpreting incoming slots to determine to which virtual circuit each of said incoming slots belong, and means for allocating outgoing slots to virtual circuits requiring such slots and for deallocating slots from virtual circuits no longer requiring slots, and

wherein the transmission on a spurt of user data over one of said virtual circuits is preceded by a header comprising sufficient bits to equal n (n≧

1) slots, said header being transmitted by at least one of said switching nodes in the first n available but not necessarily consecutive slots of the next occurring frame or frames containing available slots, no user data belonging to a virtual circuit being transmitted in the slots of the frame or frames in which header slots belonging to that virtual circuit are also transmitted.

3. A switching node for use in a virtual circuit communications network comprising an array of interconnected switching nodes and capable of supporting multiple bit rate communications, said switching node comprising,

means for synchronously exchanging frames of data with neighboring switching nodes, said frames being divided into slots,

means for allocating slots transmitted to said neighboring switching nodes among a plurality of virtual circuits passing through said switching node, virtual circuits having different bit rates being allocated different numbers of slots in each frame, and

means for interpreting incoming slots received from said neighboring switching nodes to determine to which virtual circuit each of said incoming slots belong.

4. A switching node for use in a virtual circuit communications network comprising an array of interconnected switching nodes and capable of supporting multiple bit rate communications, said switching node comprising,

a high bit rate data bus arranged in a ring-like configuration,

a plurality of port elements located at various positions along said bus for transferring data off of and onto said data bus,

interface means associated with at least some of said port elements for transmitting data from said port elements to neighboring switching nodes and for receiving data from said neighboring switching nodes for transmission to said data bus by way of said port elements,

said interface means synchronously transmitting to and synchronously receiving from said neighboring switching nodes frames of data, each of said frames comprising slots,

said interface means comprising first mapping means for allocating different numbers of slots in each frame to different virtual circuits so that different virtual circuits can have different bit rates, and second mapping means for determining which virtual circuit each of the incoming slots belongs to.

5. A transmission network for enabling communication between pairs of user stations at multiple bit rate transmissions comprising a plurality of switches including means for defining virtual circuits for synchronous transmission of data bursts between adjacent switches in frames comprising time slots and means for allocating different numbers of time slots in said frames to individual ones of said virtual circuits between the same adjacent switches.

6. A transmission network in accordance with claim 5 wherein said allocating means include frame mapping means for tracking which time slots in each frame are being used by which virtual circuit and which time slots are free.

7. A method for synchronous transmission of data bursts between adjacent switching nodes comprising the steps of synchronously exchanging data in frames between adjacent switching nodes, said frames being divided into time slots, allocating a different number of said time slots to different virtual circuits between said switching nodes, and transmitting heading information for a data burst in the first available time slots in a frame, said time slots containing said heading information not necessarily being consecutive and no user data belonging to a virtual circuit being transmitted in the frame or frames in which header time slots belonging to that virtual circuit are also transmitted.