Synchronized transport across non-synchronous networks

• US 6,747,996 B2
• Filed: 12/07/2000
• Issued: 06/08/2004
• Est. Priority Date: 12/08/1999
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Fischer, Matthew James, Trachewsky, Jason Alexander, Holloway, John T.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US09/732,213
• Publication Number:
  US 20010030978A1
• Time in Patent Office: 1,279 Days
• Field of Search: 370/401, 370/503, 370/504, 370/508, 370/509, 370/516, 370/465
• US Class Current: 370/503
• CPC Class Codes: H04J 3/0664 unidirectional timestamps
• CPC Class Codes: H04L 12/2854 Wide area networks, e.g. public data networks
• CPC Class Codes: H04L 2012/6454 Random, e.g. Ethernet
• CPC Class Codes: H04L 2012/6481 Speech, voice

Abstract

A method of providing for synchronizing one or more synchronous terminals with one or more synchronous endpoints, each synchronous terminal and each synchronous endpoint having an asynchronous communications network coupled between at least one synchronous terminal and at least one synchronous endpoint. A synchronization protocol is established between a synchronous terminal and a synchronous end point by providing a gateway between the asynchronous communications network and the synchronous end point, the gateway communicating with the synchronous terminal over the asynchronous communications network in accordance with the synchronization protocol. The synchronization protocol includes sending a message from the gateway to the synchronous terminal, the message containing a timestamp identifying a clock associated with the synchronous end point. The synchronous terminal establishes a clock associated with the synchronous terminal by creating a clock estimate based upon the timestamp message and access jitter expected from the asynchronous communications network such that the clock associated with the synchronous terminal enables packet sampling and transmission onto the asynchronous communications network to and from the synchronous terminal to be synchronized with the clock associated with the synchronous end point.

Claims

1. A method of synchronizing one or more synchronous terminals with one or more synchronous endpoints, each synchronous terminal and each synchronous endpoint having an asynchronous communications network coupled between at least one synchronous terminal and at least one synchronous endpoint, comprising:

establishing a synchronization protocol between a synchronous terminal and a synchronous end point by providing a gateway between the asynchronous communications network and the synchronous end point, the gateway communicating with the synchronous terminal over the asynchronous communications network in accordance with the synchronization protocol;

wherein the synchronization protocol includes sending a message from the gateway to the synchronous terminal, the message containing a timestamp identifying a clock associated with the synchronous end point;

wherein the synchronous terminal establishes a clock associated with the synchronous terminal by creating a clock estimate based upon the timestamp message and access jitter expected from the asynchronous communications network such that the clock associated with the synchronous terminal enables packet sampling and transmission onto the asynchronous communications network to and from the synchronous terminal to be synchronized with the clock associated with the synchronous end point.

2. The method of claim 1, wherein an attempted transmission by each terminal over the asynchronous communications network is ordered such that each synchronous terminal attempts to transmit at the same time after the message is sent from the gateway.

3. The method of claim 2, wherein each synchronous terminal retains ordering information from collision resolution cycles.

4. The method of claim 3, wherein the ordering information is used repeatedly for further transmissions in place of collision resolution.

5. The method of claim 1, wherein the synchronization protocol includes establishing keep-out windows for terminals coupled to the asynchronous communications network having a terminal access priority lower than an access priority for the one or more synchronous terminals, the keep-out windows preventing the terminals coupled to the asynchronous communications network having a terminal access priority lower than an access priority for the one or more synchronous terminals from transmitting on the asynchronous communications network before the completion of sending a message from the gateway to the synchronous terminal.

6. The method of claim 1, wherein the access jitter includes one or more of:

basic access delay, collision resolution delay, or priority access delay.

7. The method of claim 1, wherein the asynchronous communications network implements HPNA technology.