Data network for real time information

• US 6,556,561 B1
• Filed: 12/31/1998
• Issued: 04/29/2003
• Est. Priority Date: 12/31/1998
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Corporation
• Inventors: Himbeault, Lee C., Senyshyn, Paul Andrew, Wollensak, Martin
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Pham, Brenda
• Application Number:
  US09/223,991
• Time in Patent Office: 1,580 Days
• Field of Search: 370/235, 370/237, 370/352, 370/353, 370/356, 370/363, 370/445, 370/461, 370/456, 370/459, 370/462
• US Class Current: 370/352
• CPC Class Codes: H04L 12/4015 by scheduling the transmission of messages at the communication node
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 12/64 Hybrid switching systems

Abstract

A node on a collision detection protocol based network forces collisions to gain control of the network when it has real time data that needs to be transferred to another node on the network, and then begins transmitting the real time data prior to other nodes gaining control of the network. Each node which has real time data to transfer keeps track of a maximum wait time parameter to determine when the real time data must be transferred to ensure it arrives at a destination on time. As the maximum wait time is approached, the node forces a collision by transmitting even though it senses another node is already transmitting to force the network into a quiet mode. It then starts transmitting the real time data prior to other nodes beginning transmission.

Claims

1. A method of transmitting real time data on a carrier sense collision detection network, the method comprising:

establishing a maximum wait time for a real time data item;

forcing a collision when the maximum wait time is reached; and

transmitting the real time data item after the network becomes quiet as a result of the forced collision.

2. The method of claim 1 wherein the real time data item is transmitted following expiration of a collision detection timer.

3. A method of transmitting real time data from one of many nodes on a carrier sense, multiple access, collision detection network, the method comprising:

queuing real time data items having maximum wait times;

forcing a collision when the maximum wait time is reached for a real time data item; and

transmitting the real time data item after a collision detection timer value has been passed.

4. The method of claim 3 wherein the collision detection timer of the node having real time data items has a value selected to be less than that of other nodes.

5. The method of claim 3 wherein the real time data is audio data.

6. The method of claim 3 wherein the network protocol is shared Ethernet.

7. A system for transmitting real time data on a carrier sense collision detection network, the system comprising:

a queue that identifies packets of real time data and associates a maximum wait time for each packet;

a monitor that detects when the maximum wait time is reached for each real time data packet;

a transmitter that forces collisions on the network when the maximum wait time is reached for each packet and transmits the real time packet following a quiet period of the network.

8. The system of claim 7 and further comprising a connector for coupling the system to a network.

9. The system of claim 8 wherein the network comprises a shared Ethernet network.

10. A system for transmitting real time data on a carrier sense collision detection network, the system comprising:

means for identifying packets of real time data and associates a maximum wait time for each packet;

means for detecting when the maximum wait time is reached for each real time data packet;

means for forcing collisions on the network when the maximum wait time is reached for each packet and transmits the real time packet following a quiet period of the network.

11. The system of claim 10 and further comprising:

means for providing a time at which to begin transmitting the real time data packet in the quite period following a forced collision.

12. A node for coupling to a shared carrier sense, multiple access, collision detection network having multiple nodes coupled thereto, the node comprising:

a network busy detector;

a collision detector;

a collision forcer;

a collision detection timer having a shorter value than other nodes on the network.

13. The node of claim 12, and further comprising a voice over IP gateway server coupled to the node.

14. The node of claim 13, and further comprising a frame relay access device coupled to the node.

15. A network comprising:

a plurality of normal nodes implementing a shared Ethernet protocol coupled to the network;

a first real time data node coupled to the network that has the ability to force collisions and transmit real time data prior to the normal nodes beginning to transmit data following a collision; and

a second real time data node coupled to the network that has the ability to force collisions and transmit real time data prior to the normal nodes beginning to transmit data following a collision, wherein the first real time data node is a voice over IP gateway server and the second real time data node is a router coupled to a further network.

16. A network comprising:

a plurality of normal nodes implementing a shared Ethernet protocol coupled to the network;

a first real time data node coupled to the network that has the ability to force collisions and transmit real time data prior to the normal nodes beginning to transmit data following a collision; and

a second real time data node coupled to the network that has the ability to force collisions and transmit real time data prior to the normal nodes beginning to transmit data following a collision, wherein the first real time data node comprises a queue having maximum wait times associated with real time data items to be sent.

17. The network of claim 16 wherein the maximum wait time is a function of the time at which such real time data should be received.

18. The network of claim 17 wherein the real time data is voice data.

19. A machine readable medium having instructions stored thereon for causing a computer to perform a method of transmitting real time data on a carrier sense collision detection network, the method comprising:

establishing a maximum wait time for a real time data item;

forcing a collision when the maximum wait time is reached; and

transmitting the real time data item after the network becomes quiet as a result of the forced collision.

20. A machine readable medium having instructions stored thereon for causing a computer to perform a method of transmitting real time data from one of many nodes on a carrier sense, multiple access, collision detection network, the method comprising:

queuing real time data items having maximum wait times;

forcing a collision when the maximum wait time is reached for a real time data item; and

transmitting the real time data item after a collision detection timer value has been passed.