Method for transmitting high-priority packets in an IP transmission network

• US 20050175013A1
• Filed: 08/11/2003
• Published: 08/11/2005
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Le Pennec, Jean-Francois, Galand, Claude, Giroir, Didier F.
• Granted Patent: US 7,558,269 B2
• Time in Patent Office: Days
• US Class Current: 370/395.420
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2408 for supporting different services, e.g. a differentiated services [DiffServ] type of service
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/245 using preemption

Abstract

Method for transmitting high-priority packets in an IP transmission network based upon the Internet Protocol (IP) wherein low-priority packets or fragments of packets are transmitted between a sender and a receiver and at least a high-priority packet can be transmitted from the sender to the receiver by pre-emption of a low-priority packet or a fragment of packet. The method comprises in the sender, the steps of determining whether a low-priority packet or fragment of packet is being transmitted from the sender to the receiver when a high-priority packet has to be transmitted, setting to 1 a reserved bit within the IP header of the high-priority packet used as a pre-emption indicator if a low-priority packet or fragment of packet is currently transmitted, transmitting the high-priority packet with the pre-emption indicator set to 1 from the sender to the receiver, and resuming the transmission of the low-priority packet or fragment of packet at the end of transmission of the high-priority packet.

Claims

1-14. -14. (canceled)

15. A method for transmitting high priority packets in an Internet Protocol (IP) based transmission network wherein low-priority packets or fragments of packets are transmitted between a transmitter and a receiver and wherein high priority packets pre-empt low-priority packets, the method comprising the steps of:

determining whether a low-priority packet or a fragment of a low-priority packet is being transmitted from the transmitter to the receiver when a high-priority packet requires transmission;

activating a reserved bit within the IP header of the high-priority packet, as a pre-emption indicator, in the event that a low-priority packet or a fragment of a low-priority packet is being transmitted;

transmitting the high-priority packet having the pre-emption indicator activated; and

restarting the transmission of the low-priority packet or the fragment of the low-priority packet after having transmitted the high-priority packet.

16. The method of claim 15, wherein the pre-emption indicator is not activated in the event that no low-priority packet or fragment is being transmitted when the high-priority packet is transmitted.

17. The method of claim 16, further comprising the step of using the reserved bit within the IP header as a packet start indicator in each low-priority packet or fragment.

18. The method of claim 17, wherein the reserved bit used as a packet start indicator is set to 1 in a first segment of a low-priority packet or fragment being transmitted, the reserved bit being reset when a high-priority packet requires transmission and a low-priority packet or fragment is pre-empted.

19. The method of claim 18 further comprising the step of transmitting a sweep packet when no high-priority packet requires transmission after a low-priority packet or fragment has been transmitted, the sweep packet being a packet without data indicating that the previous transmission of a low-priority packet or fragment has been completed.

20. The method of claim 19, wherein the reserved bit is within the flag field within the IP header of a packet.

21. A method for transmitting high priority packets in an Internet Protocol (IP) based transmission network wherein low-priority packets or fragments of packets are transmitted between a transmitter and a receiver and wherein high priority packets pre-empt low-priority packets, the method comprising the steps of:

determining whether a high-priority packet has been received by the receiver;

determining whether a reserved bit within the IP header of the high-priority packet has been activated; and

waiting for reception of a new packet if the reserved bit has been activated, the activated reserve bit indicating that the high-priority packet has pre-empted a low-priority packet.

22. The method according to claim 21, wherein a previous received low-priority packet or fragment is delivered to the upper layer when the reserved bit used as a pre-emption indicator has been activated in the high-priority packet, and wherein an inactivated pre-emption indicator indicates that the transmission of the previous low-priority packet or fragment has been completed.

23. The method according to claim 22, further comprising the step of determining whether the reserved bit used as a packet start indicator has been activated when the packet being received by the receiver is a low-priority packet or fragment, the low-priority packet or fragment being a segment to be appended to the received low-priority packet or fragment if the packet start indicator is inactive.

24. The method of claim 23, wherein the received low-priority packet or fragment is delivered to the upper layer when the reserved bit used as a packet start indicator is active, indicating that the reception of the previous low-priority packet or fragment has been completed.

25. The method of claim 24, further comprising the step of determining whether the packet being received is a sweep packet without data, the sweep packet indicating that the transmission of a low-priority packet or fragment has been completed.

26. The method of claim 25, wherein the step of determining whether the packet being received is a low-priority packet or a high-priority packet is determined by a type of service field within the IP header of the received packet.

27. The method of claim 26, wherein the reserved bit is a bit within a flag field within the IP header of the packet.

28. The method of claim 27, wherein the high-priority packet is a voice packet and the low-priority packet or fragment is a data packet or fragment.