Packet voice/data communication system having protocol independent repetitive packet suppression

• US 5,020,058 A
• Filed: 01/23/1989
• Issued: 05/28/1991
• Est. Priority Date: 01/23/1989
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: StrataCom, Inc. (Cisco Systems, Inc.)
• Inventors: Schultz, Gaymond W., Robertson, William L., Holden, Brian D., Presuhn, Randall M.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Hsu, Alpus H.
• Application Number:
  US07/299,404
• Time in Patent Office: 855 Days
• Field of Search: 370/118, 370/109, 370/60, 370/79, 370/94.1, 370/95.1, 340/825.5, 340/825.53, 375/122, 375/27, 375/31, 358/133, 358/135, 358/136, 381/29, 381/30, 381/34, 382/56, 341/60, 341/87, 341/51
• US Class Current: 370/474
• CPC Class Codes: H03M 7/46 Conversion to or from run-length codes, i.e. by representing the number of consecutive digits, or groups of digits, of the same kind by a code word and a digit indicative of that kind
• CPC Class Codes: H04L 12/64 Hybrid switching systems

Abstract

A data communication system includes a repetitive pattern packet suppression technique which suppresses transmission of entire packets in a data stream when a repeating pattern has been established in the previous packet and then is found to repeat throughout the following packets. An expansion part of the technique fills the resulting hole in the data stream with the last pattern from the previously received packet.

Claims

1. A package voice/data communication system comprising

means for transmitting data packets in a data bit stream from a first location to one or more second locations over a multi-time slot digital facility,

means for queuing said data packets along with voice packets,

compression means at said first location for determining whether said data stream has one or more data packets filled with repetitive patterns of configurable length, said compression means including means for suppressing said data packets such that the suppressed data packets are not transmitted to said second locations,

means at said first location for controlling the impact of bit errors and dropped packets by sending a packet if a certain number of consecutive data packets have been suppressed,

expansion means at said second location for replicating said repetitive patterns into the portion of said data stream which corresponds to the suppressed data packets.

2. The system as in claim 1 wherein said compression means and said expansion means are protocol independent.

3. A packet voice/data system as in claim 1 wherein said compression means allow overloads of voice packets and data packets to be handled separately.

5. A packet voice/data communication system as in claim 2 wherein the data packets have a user selected pattern size and wherein said system includes means for continuously comparing in a pattern hunt state the pattern sizes on a bit by bit basis of incoming samples such that when the first incoming sample matches all bits of the pattern, a repeat pattern state is acquired.

6. A system as in claim 5 including means for operating in said repeat pattern state such that the last sample in the previous packet matches every sample in the present packet.

7. A system as in claim 6 including means for operating in a suppress packet state such that the system stays in a suppress packet state for no more than a predetermined number of consecutive packets, and after the last packet has been suppressed, the system sends a heartbeat packet to maintain synchronization between said locations and to reduce the impact of bit errors and dropped packets.

8. A system as in claim 7 wherein said system includes means for sending a packet to said second locations after said predetermined number of consecutive packets have been suppressed.

9. A system as in claim 8 wherein each of said second locations includes a pattern register and means for operating in a fill pattern hunt state such that received bits are shifted out through said pattern register.

10. A system as in claim 9 including means for operating in an expand packet state, including means for retrieving bits from said pattern register, and means for recirculating said pattern register.

11. A system as in claim 10 wherein all of the components of the system are implemented as a program in a field programmable gate array.

4. In a packet voice/data communication system, the method comprising the steps of

transmitting data packets in a data stream from a first location to one or more second locations over a multi-time slot digital facility,

queuing said data packets along with voice packets,

determining at said first location whether said data stream has one or more data packets filled with repetitive patterns of configurable length,

suppressing repetitive ones of said packets such that the suppressed packets are not transmitted to said second locations, and

replicating at said second locations said repetitive patterns into the portion of said data stream which corresponds to the suppressed packets.