Providing time synchronization across store-and-forward communication devices using protocol-enabled switches

• US 20040246996A1
• Filed: 06/04/2003
• Published: 12/09/2004
• Est. Priority Date: 06/04/2003
• Status: Active Grant

• Current Assignee: Keysight Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Engel, Glenn R.
• Granted Patent: US 7,397,823 B2
• Time in Patent Office: Days
• US Class Current: 370/508
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864
• CPC Class Codes: H04J 3/0673 using intermediate nodes, e.g. modification of a received timestamp before further transmission to the next packet node, e.g. including internal delay time or residence time into the packet
• CPC Class Codes: H04L 12/56 Packet switching systems

Abstract

Techniques for using protocol-enabled switches to provide time synchronization across store-and forward communication devices. A protocol-enabled switch according to the present techniques bypasses a store-and forward communication device for the purposes of time synchronization by merging timing packets into each subnet serviced by the store-and forward communication device, thereby avoiding the variable delays that may occur in the store-and forward communication device.

Claims

1. A communication network, comprising:

store-and-forward communication device having a set of subnet ports each for communicating via a corresponding subnet of nodes wherein one or more of the nodes synchronize a local time using a protocol that includes a set of timing packets that are ignored by the store-and-forward communication device;

protocol-enabled switch that provides the timing packets for each subnet according to the protocol.

2. The communication network of claim 1, wherein each subnet of nodes connects to the store-and-forward communication device and the protocol-enabled switch via a corresponding network communication device.

3. The communication network of claim 2, wherein the network communication device is a switch.

4. The communication network of claim 2, wherein the network communication device is a hub.

5. The communication network of claim 2, wherein the network communication device is another protocol enabled switch.

6. The communication network of claim 1, wherein the protocol-enabled switch is configured to not relay any packets among the subnets.

7. The communication network of claim 1, wherein each subnet includes a network distribution device that connects to the corresponding subnet port and to a corresponding switch port of the protocol-enabled switch.

8. The communication network of claim 1, wherein each subnet includes a network distribution device that connects to the corresponding subnet port and to a corresponding switch port of the protocol-enabled switch via a corresponding hub.

9. The communication network of claim 1, wherein the protocol-enabled switch includes a switch port pair for each subnet that connects between the corresponding subnet port and a network distribution device for the corresponding subnet.

10. A method for providing time synchronization across a store-and-forward communication device, comprising the steps of:

connecting each of a set of subnet ports of the store-and-forward communication device to a corresponding subnet of nodes wherein one or more of the nodes synchronize a local time using a protocol that includes a set of timing packets that are ignored by the store-and-forward communication device;

connecting a protocol-enabled switch to the subnets of nodes such that the protocol-enabled switch provides the timing packets for each subnet according to the protocol.

11. The method of claim 10, wherein the steps of connecting include the step of connecting each subnet of nodes to the store-and-forward communication device and the protocol-enabled switch via a corresponding network communication device.

12. The method of claim 11, wherein the step of connecting each subnet of nodes to the store-and-forward communication device and the protocol-enabled switch via a corresponding network communication device comprises the step of connecting each subnet of nodes to the store-and-forward communication device and the protocol-enabled switch via a switch.

13. The method of claim 11, wherein the step of connecting each subnet of nodes to the store-and-forward communication device and the protocol-enabled switch via a corresponding network communication device comprises the step of connecting each subnet of nodes to the store-and-forward communication device and the protocol-enabled switch via a hub.

14. The method of claim 11, wherein the step of connecting each subnet of nodes to the store-and-forward communication device and the protocol-enabled switch via a corresponding network communication device comprises the step of connecting each subnet of nodes to the store-and-forward communication device and the protocol-enabled switch via another protocol enabled switch.

15. The method of claim 10, further comprising the step of configuring the protocol-enabled switch to not relay any packets among the subnets.

16. The method of claim 10, wherein the steps of connecting include the step of connecting a network distribution device to a corresponding subnet port and to a corresponding switch port of the protocol-enabled switch.

17. The method of claim 10, wherein the steps of connecting include the step of connecting a network distribution device to a corresponding subnet port and to a corresponding switch port of the protocol-enabled switch via a corresponding hub.

18. The method of claim 10, wherein the steps of connecting include the step of connecting a switch port pair for each subnet between the corresponding subnet port and a network distribution device for the corresponding subnet.