Synchronous packet voice/data communication system

• US 4,903,261 A
• Filed: 03/09/1988
• Issued: 02/20/1990
• Est. Priority Date: 10/29/1984
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: StrataCom, Inc. (Cisco Systems, Inc.)
• Inventors: Owen, David P., Baran, Paul, Holden, Brian D., Stonebridge, Peter W. J., Corbalis, Charles M., Masatsugu, Jon K., Marggraff, Lewis J.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): Scutch, III, Frank M.
• Application Number:
  US07/165,867
• Time in Patent Office: 713 Days
• Field of Search: 370/60, 370/94, 370/85, 370/109, 370/118
• US Class Current: 370/396
• CPC Class Codes: H04L 12/64 Hybrid switching systems
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04Q 2213/13031 Pulse code modulation, PCM
• CPC Class Codes: H04Q 2213/13034 A/D conversion, code compression/expansion
• CPC Class Codes: H04Q 2213/1309 Apparatus individually associated with a subscriber line, line circuits
• CPC Class Codes: H04Q 2213/13096 Digital apparatus individually associated with a subscriber line, digital line circuits
• CPC Class Codes: H04Q 2213/13103 Memory
• CPC Class Codes: H04Q 2213/13174 Data transmission, file transfer
• CPC Class Codes: H04Q 2213/13196 Connection circuit/link/trunk/junction, bridge, router, gateway
• CPC Class Codes: H04Q 2213/13201 Change-over of service during connection
• CPC Class Codes: H04Q 2213/13216 Code signals, frame structure
• CPC Class Codes: H04Q 2213/1322 PBX
• CPC Class Codes: H04Q 2213/13292 Time division multiplexing, TDM
• CPC Class Codes: H04Q 2213/13299 Bus

Abstract

A packet communications network and apparatus for communicating information in voice and data packets transmits and receives voice and data in accordance with standardized frames of a standardized communications format such as a standard DS-1 type trunk. An apparatus is coupled to multiplex standardized channels into a single channel wherein voice or data signals are packetized into independently addressable packets synchronized on, for example, the DS-1 frame. The network includes voice and packet data concentration apparatus operable in a multiple node trunk environment to concentrate signals into independently addressable synchronously switchable packets, thereby to provide an efficient (high density capacity) interface between trunk terminations. Up to four times as much information can be transferred between nodes with the ability to switch between nodes as compared to conventional TDM and PCM communication without compression without the ability to switch between nodes.

Claims

1. A communications network for communicating digitized voice and data in separate and distinct packets, said network comprising:

a digital communications medium having at least a first node and a second node, said digital communications medium being operative to communicate standardized bit synchronous digital time frames of information according to a standardized bit synchronous communications format having a predetermined bit synchronous framing structure; and

means for coupling digital signals bit synchronously to said digital communications medium at said first node, said coupling means including means for packetizing signals into digitized information packets, each said digitized information packet having a packet format which is self contained as to destination and content and which conforms bit synchronously to said bit synchronous communications format and to boundaries of said standardized bit synchronous digital time frames such that packets are communicated from said first node to said second node bit synchronously with reference to said communications medium within said standardized bit synchronous communications format such that an additional framing structure is not needed.

2. The network according to claim 1 wherein said communications medium further includes at least a third node and wherein said coupling means further includes means for switching said digitized information packet at least from said first node to said second node or to said third node wherein at least said first, second and third nodes maintain packet switching synchronization with one another.

3. The network according to claim 2 wherein said switching means further includes means for switching said digitized information packet at least from said first node to said second node and then to said third wherein at least said first, second and third nodes maintain packet switching synchronization with one another.

4. The network according to claim 1 wherein said standardized communications format is a DS-1 Trunk Communications format having a 193 bit frame and wherein each said digitized information packet has as a format a 24-bit address and error correction field and a 168-bit information field and a 1-bit synchronization field.

5. The network according to claim 4 wherein said digitized information packet may be a voice packet, said voice packet employing a four-bit voice code in normal operation.

6. The network according to claim 4 wherein said digitized information packet may be a data packet, said data packet employing an 8-bit data byte in normal operation.

7. The network according to claim 1 wherein said packetizing means includes means for switching individual voice and data packets with a delay of less than eighteen milliseconds during normal operation.

8. The network according to claim 7 wherein said packetizing means creates and forwards individual voice and data packets.

9. The network according to claim 5 wherein said packetizing means creates and forwards individual voice packets with a delay not greater than eighteen milliseconds during normal operation.

10. The network according to claim 1 wherein said digitized information packet is a voice packet, said voice packet employing a 4-bit voice code in normal operation.

11. The network according to claim 1 wherein said digitized information packet is a data packet, said data packet employing and 8-bit data byte in normal operation.

12. For use in a communications network for communicating data and voice in separate and distinct information packets, including voice packets and data packets, through a bit synchronous digital communications medium, an apparatus for coupling digital signals to said communications medium comprising:

a multiplexing bus, said multiplexing bus including a clock line for synchronizing said information packets;

a multiplexing bus controller coupled to said multiplexing bus and operative to generate a clock signal said clock line to control switching of said information packets, said information packets comprising independently addressable digital data conforming to a standardized bit synchronous time frame and a standardized bit synchronous communications format having a predetermined bit synchronous framing structure;

means for packetizing signals into digitized information packets, each said digitized information packet having a packet format which is self-contained as to destination and content and which conforms to boundaries of said standardized bit synchronous time frame; and

first digital communications means coupled to said multiplexing bus for transmitting said information packets to said bit synchronous digital communications medium and for receiving said information packets from said bit synchronous digital communications medium, said first digital communications means being operative to communicate said information packets bit synchronously according to said standardized bit synchronous communications format such that an additional framing structure is not needed.

13. The apparatus according to claim 12 further including means coupled to said multiplexing bus for compressing voice signals and for decompressing voice signals.

14. The apparatus according to claim 13 wherein said voice packets are dropped in the event of over capacity operation of said communications medium.

15. The apparatus according to claim 12 further including at least one packet framing transceiver for receiving and transmitting digitized information packets according to said standardized communications format, and means coupling said packet transceiver to said communications medium, said packet transceiver further including means for coupling address, timing and information signals to said multiplexing bus.

16. The apparatus according to claim 15 wherein said packet transceiver comprises:

means for inserting framing and signaling information into a standardized time frame in said standardized communications format; and

means for extracting framing and signaling information from a standardized time frame in said standardized communication format.

17. The apparatus according to claim 16 wherein said packet framing transceiver further includes means coupled to said multiplexing bus for receiving and serially forwarding said information packet, and means coupled to said multiplexing bus for transferring TDM signals.

18. The apparatus according to claim 12 wherein said packet control unit includes:

a packet receiver coupled to said multiplexing bus;

a packet transmitter coupled to said multiplexing bus; and

a multiplexing bus controller coupled to said multiplexing bus for controlling operation of said multiplexing bus.

19. The apparatus according to claim 12 wherein said standardized communication format is a DS-1 trunk communication format having a 193 bit frame and wherein each said information packet has a format comprising an 168 bit data packet field and a 24 bit address and error correction field, said packet format being confined to one information packet per standardized frame.

20. The apparatus according to claim 19 wherein said information packet employs a four bit voice code in normal operation.

21. For use in a communications network for communicating data and voice in separate and distinct information packets, including voice packets and data packets, through a bit synchronous digital communications medium, an apparatus for coupling digital signals to said communications medium comprising:

a multiplexing bus, said multiplexing bus including a clock line for synchronizing said information packets;

a multiplexing bus controller coupled to said multiplexing bus and operative to generate a clock signal on said clock line to control switching of said information packets, said information packets comprising independently addressable digital data conforming to a standardized bit synchronous time frame and a standardized bit synchronous communications format;

means coupled to said multiplexing bus for compressing voice signals and for decompressing voice signals;

means for packetizing signals into digitized information packets, each said digitized information packet having a packet format which is self-contained as to destination and content and which conforms to boundaries of said standardized bit synchronous time frame; and

first digital communications means coupled to said multiplexing bus for transmitting said information packets to said bit synchronous digital communications medium and for receiving said information packets from said bit synchronous digital communications medium, said first digital communications means being operative to communicate said information packets bit synchronously according to said standardized bit synchronous communications format, wherein said voice packets are dropped in the event of over capacity operation of said communications medium.