Dynamic keepalive parameters for reverse path validation in computer networks

1. A method, comprising:

determining a path from a network device to a source device in a computer network, wherein the source device utilizes the path in reverse from the source device to the network device to reach the network device;

determining a reliability of a plurality of links connecting a plurality of nodes along the path in reverse by the network device;

dynamically adjusting one or more keepalive parameters for keepalive messages sent on the path based on the reliability of the path in reverse; and

sending keepalive messages on the path based on the dynamically adjusted keepalive parameters,

wherein in response to failure of the keepalive messages on the path, the network device repairs a broken path to the source device with a route change.

2. The method as in claim 1 , wherein determining the reliability comprises:

observing a retransmission count contained in messages received at the network device from the path in reverse.

3. The method as in claim 2 , wherein the messages are data messages.

4. The method as in claim 1 , wherein determining the reliability comprises:

determining an expected retransmission count (ETX) metric for the path in reverse.

5. The method as in claim 1 , wherein adjusting the keepalive parameters comprises:

adjusting a rate at which keepalive messages are sent.

6. The method as in claim 5 , wherein adjusting further comprises:

increasing the rate in response to the reliability surpassing an unacceptable reliability threshold; and

decreasing the rate in response to the reliability surpassing an acceptable reliability threshold.

7. The method as in claim 6 , further comprising:

adjusting the rate respectively in increments in response to the reliability continuing to surpass the corresponding reliability threshold.

8. The method as in claim 1 , wherein adjusting the keepalive parameters comprises:

adjusting a hop distance for which keepalive messages are sent.

9. The method as in claim 8 , wherein adjusting further comprises:

increasing the hop distance in response to the reliability surpassing an unacceptable reliability threshold; and

decreasing the hop distance in response to the reliability surpassing an acceptable reliability threshold.

10. The method as in claim 9 , further comprising:

adjusting the hop distance respectively in increments in response to the reliability continuing to surpass the corresponding reliability threshold.

11. The method as in claim 1 , wherein adjusting the keepalive parameters comprises:

adjusting a rate at which keepalive messages are sent and a hop distance for which keepalive messages are sent.

12. The method as in claim 11 , wherein adjusting further comprises:

increasing the rate;

determining that the reliability continues to surpass an unacceptable reliability threshold; and

in response, increasing the hop distance.

13. The method as in claim 1 , further comprising:

determining an acceptable reliability threshold and an unacceptable reliability threshold on an individual device basis.

14. The method as in claim 1 , wherein the source device is a root device of a directed acyclic graph (DAG).

15. An apparatus, comprising:

one or more network interfaces to communicate in a computer network;

a processor coupled to the network interfaces and adapted to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed operable to:

determine a path from the apparatus to a source device in the computer network, wherein the source device utilizes the path in reverse from the source device to the apparatus to reach the apparatus;

determine a reliability of a plurality of links connecting a plurality of nodes along the path in reverse;

dynamically adjust one or more keepalive parameters for keepalive messages sent on the path based on the reliability of the path in reverse; and

send keepalive messages on the path based on the dynamically adjusted keepalive parameters,

wherein in response to failure of the keepalive messages on the path, the network device repairs a broken path to the source device with a route change.

16. The apparatus as in claim 15 , wherein the process when executed to determine the reliability is further operable to:

observe a retransmission count contained in messages received at the apparatus from the path in reverse.

17. The apparatus as in claim 15 , wherein the process when executed to adjust the keepalive parameters is further operable to:

adjust a rate at which keepalive messages are sent.

18. The apparatus as in claim 17 , wherein the process when executed to adjust is further operable to:

increase the rate in response to the reliability surpassing an unacceptable reliability threshold; and

decrease the rate in response to the reliability surpassing an acceptable reliability threshold.

19. The apparatus as in claim 15 , wherein the process when executed to adjust the keepalive parameters is further operable to:

adjust a hop distance for which keepalive messages are sent.

20. The apparatus as in claim 19 , wherein the process when executed to adjust is further operable to:

increase the hop distance in response to the reliability surpassing an unacceptable reliability threshold; and

decrease the hop distance in response to the reliability surpassing an acceptable reliability threshold.

21. The apparatus as in claim 15 , wherein the process when executed to adjust the keepalive parameters is further operable to:

adjust a rate at which keepalive messages are sent and a hop distance for which keepalive messages are sent.

22. A tangible, non-transitory, computer-readable media having software encoded thereon, the software when executed by a processor on a network device operable to:

determine a path from a network device to a source device in a computer network, wherein the source device utilizes the path in reverse from the source device to the network device to reach the network device;

determine a reliability of a plurality of links connecting a plurality of nodes along the path in reverse by the network device;

dynamically adjust one or more keepalive parameters for keepalive messages sent on the path based on the reliability of the path in reverse; and

send keepalive messages on the path based on the dynamically adjusted keepalive parameters,

wherein in response to failure of the keepalive messages on the path, the network device repairs a broken path to the source device with a route change.

23. The computer-readable media as in claim 22 , wherein the software when executed to determine the reliability is further operable to:

observe a retransmission count contained in messages received at the network device from the path in reverse.

24. The computer-readable media as in claim 22 , wherein the software when executed to adjust the keepalive parameters is further operable to adjust at least one parameter selected from the group consisting of: a rate at which keepalive messages are sent; and a hop distance for which keepalive messages are sent.