Patent ID: 7558269

Claim:
A method performed by a packet transmitter 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, performed by the transmitter, 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, and suspending transmission of said low-priority packet or fragment of a low-priority packet, 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, wherein the reserved bit is within the IP header as a packet start indicator in each low-priority packet or fragment, wherein the reserved bit used as a packet start indicator is set to a first binary value in a first segment of a low-priority packet or fragment being transmitted, the reserved bit being reset to a second binary value when a high-priority packet requires transmission and a low-priority packet or fragment is pre-empted, and wherein the reserved bit is within the flag field within the IP header of a packet.