Sender-initiated recovery algorithm (SIRA) for the layer 2 tunneling protocol (L2TP)
View Patent ↗A Layer 2 Tunneling Protocol (L2TP) performs a sender initiated recovery algorithm (SIRA) upon receiving, from an L2TP receiver, a predefined number of packets including the same “next received” (Nr) sequence number. The L2TP sender transmits a payload message that includes the “Reset Sr” (R-bit) indicator, which resets the value for Nr (at the receiver) to either just beyond the first missing packet or to the current send sequence number of the sender.
1. A recovery method for use at a layer 2 tunneling protocol (L2TP) sender, the method comprising the steps of:
sending packets directed to an L2TP peer; and
initiating a recovery process upon detection of a predetermined number of negative acknowledgements being received from the L2TP peer indicative that the L2TP peer is still waiting for a prior transmitted packet.
2. The method of claim 1 wherein the multiple messages are negative acknowledgements.
3. The method of claim 1 wherein the initiating step includes the step of sending a packet that includes a “Reset Sr” (R-bit) indicator for resetting a next received sequence number, Nr, value at the L2TP peer.
4. A recovery method for use at a layer 2 tunneling protocol (L2TP) sender, the method comprising the steps of:
receiving a packet from an L2TP peer, the received packet including a next received sequence number, Nr; value;
determining if the Nr value represents a negative acknowledgement; and
initiating a recovery process with the L2TP peer upon determining that a predetermined number of sequentially received packets are negative acknowledgements.
5. The method of claim 4 wherein the recovery process includes the step of sending a packet that includes a “Reset Sr” (R-bit) indicator for resetting a next received sequence number, Nr, value at the L2TP peer.
6. A recovery method for use at a layer 2 tunneling protocol (L2TP) sender, the method comprising the steps of:
sending packets directed to an L2TP peer; and
initiating a recovery process upon either determining that a predetermined number of acknowledgement packets received from the L2TP peer provide an indication that the L2TP peer is still waiting for a prior transmitted packet, or occurrence of a predetermined payload time-out with respect to the prior transmitted packet.
7. The method of claim 6 wherein the multiple messages are negative acknowledgements.
8. The method of claim 6 wherein the initiating step includes the step of sending a packet that includes a “Reset Sr” (R-bit) indicator for resetting a next received sequence number, Nr, value at the L2TP peer.
9. A packet interface for use in forming a layer 2 tunneling protocol (L2TP) at an L2TP sender, the packet interface comprising:
a communications interface for sending packets directed to an L2TP peer; and
a processor for initiating a recovery process upon detection of a predetermined number of negative acknowledgements being received from the L2TP peer indicative that the L2TP peer is still waiting for a prior transmitted packet.
10. The packet interface of claim 9 wherein the multiple messages are negative acknowledgements.
11. The packet interface of claim 9 wherein the processor sends a packet that includes a “Reset Sr” (R-bit) indicator for resetting a next received sequence number, Nr, value at the L2TP peer as part of the initiated recovery process.
12. A packet interface for use in forming a layer 2 tunneling protocol (L2TP) at an L2TP sender, the packet interface comprising:
a communications interface for receiving a packet from an L2TP peer, the received packet including a next received sequence number, Nr; value; and
a processor for (a) determining if the Nr value represents a negative acknowledgement; (b) maintaining a count of sequential such negative acknowledgements having been received, and (c) initiating a recovery process with the L2TP peer upon determining that a predetermined number of sequential such negative acknowledgements have been received.
13. The packet interface of claim 12 wherein the processor sends a packet that includes a “Reset Sr” (R-bit) indicator for resetting the next received sequence number, Nr, value at the L2TP peer as part of the initiated recovery process.