Sequence number schemes for acceptance/rejection of duplicated packets in a packet-based data network

A method for transmitting packets, comprising the steps of:

• creating first and second duplicate packets from an original packet;
• tracking an inner sequence number for the original packet, wherein the inner sequence number changes between each pair of consecutive original packets;
• tracking an outer sequence number for the original packet, wherein the outer sequence number changes only after a specified number of consecutive original packets greater than two;
• selecting a sequence number for the first and second duplicate packets to be either the inner sequence number or the outer sequence number, wherein:
• if the selected sequence number is the inner sequence number, then the first and second duplicate packets are inner sequence packets;
• and
• if the selected sequence number is the outer sequence number, then the first and second duplicate packets are outer sequence packets;
• inserting the selected sequence number into a same field in the first and second duplicate packets, wherein the same field is used whether the selected sequence number is the inner sequence number or the outer sequence number;
• and
• transmitting the first and second duplicate packets along respective different paths towards a destination node, wherein a bit in each of the first and second duplicate packets identifies whether the selected sequence number is the inner sequence number or the outer sequence number, wherein a specified number of inner sequence packets are transmitted between each consecutive pair of outer sequence packets.

A method for processing received packets, comprising the steps of:

• maintaining a sliding window based on a sequence number of a previously accepted packet;
• receiving a current packet via either a first path or a second path;
• determining whether the sequence number of the current packet falls within the sliding window;
• accepting the current packet, when the sequence number of the current packet falls within the sliding window;
• rejecting the current packet, when the sequence number of the current packet falls outside of the sliding window;
• keeping track of the most significant bit (MSB) of the sequence number of the previously accepted packet;
• and
• comparing the MSB of the sequence number of the current packet with the MSB of the sequence number in the previously accepted packet to detect a roll-over of the sequence number.

A method for processing received packets, comprising the steps of:

• receiving a current packet via either a first path or a second path;
• maintaining a first least significant bit (LSB) counter and a first most significant bit (MSB) counter for the first path and a second LSB counter and a second MSB counter for the second path;
• identifying whether the current packet has been received via the first path or the second path;
• interpreting the sequence number in the current packet as an LSB sequence number;
• generating a full sequence number by concatenating a current LSB sequence number with a corresponding MSB counter value;
• and
• comparing the full sequence number to a full sequence number of a previously accepted packet.

A method for processing received packets having sequence numbers comprising the steps of:

• receiving a current packet having a current sequence number via either a first path or a second path;
• tracking which path is a leading path and which path is a trailing path;
• determining whether the current packet was received from the leading path or the trailing path;
• if the current packet was received from the leading path, then (1) accepting the current packet, (2) updating a select counter based on the current sequence number, and (3) updating a delay counter based on the current sequence number and a previous sequence number of a leading-path packet previously received from the leading path;
• if the current packet was received from the trailing path, then:
• performing a first comparison between (i) the delay counter and (ii) a difference between the current sequence number and a previous sequence number of a trailing-path packet previously received from the trailing path;
• if the first comparison indicates that the difference is less than the delay counter, then (1) rejecting the current packet and (2) updating the delay counter based on the current sequence number and the previous trailing-path sequence number;
• and
• if the first comparison indicates that the difference is greater than the delay counter, then (1) accepting the current packet;
• (2) updating the select counter based on the current sequence number, (3) updating the delay counter based on the current sequence number and the previous trailing-path sequence number;
• and (4) identifying the trailing path as the leading path.

A method for processing received packets having sequence numbers, comprising the steps of:

• storing previous inner and outer sequence numbers associated with a previously accepted packet;
• receiving a current packet having a current sequence number via either a first path or a second path, wherein a bit in the current packet identifies whether the current sequence number is an inner sequence number or an outer sequence number, wherein:
• if the current sequence number is the inner sequence number, then the current packet is an inner sequence packet;
• if the current sequence number is the outer sequence number, then the current packet is an outer sequence packet;
• and
• a specified number of inner sequence packets are transmitted between each consecutive pair of outer sequence packets;
• determining, based on the current sequence number and the bit, a current inner sequence number and a current outer sequence number for the current packet, wherein the current packet contains one of the current inner sequence number and the current outer sequence number, but not both;
• and
• comparing the current inner and outer sequence numbers for the current packet to the previous inner and outer sequence numbers associated with the previously accepted packet to determine whether to accept the current packet.