Increased Communication Opportunities with Low-Contact Nodes in a Computer Network

• US 20120155463A1
• Filed: 12/17/2010
• Published: 06/21/2012
• Est. Priority Date: 12/17/2010
• Status: Abandoned Application

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Vasseur, Jean-Philippe, Shaffer, Shmuel, Shetty, Sandeep Jay
• Application Number:
  US12/971,360
• Publication Number:
  US 20120155463A1
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1863 comprising mechanisms for improved reliability, e.g. status reports arrangements for detecting or preventing errors by carrying supervisory signal the return channel H04L1/16
• CPC Class Codes: H04L 67/145 avoiding end of session, e.g. keep-alive, heartbeats, resumption message or wake-up for inactive or interrupted session

Abstract

In one embodiment, a particular node (e.g., root node) in a directed acyclic graph (DAG) in a computer network may identify a low-contact (e.g., wireless) node in the DAG that is at risk of having an invalid path when attempts are made to reach the low-contact node. In response, the particular node may identify neighbors of the low-contact node, and may establish a multicast tree from the particular node to the low-contact node through a plurality of the neighbors to reach the low-contact node. When sending traffic to the low-contact node, the particular node sends the traffic on the multicast tree, wherein each of the plurality of neighbors attempts to forward the traffic to the low-contact node. In another embodiment, the low-contact node itself indicates its status to the particular/root node, along with its list of neighbors in order to receive the multicast traffic.

Claims

1. A method, comprising:

identifying, by a particular node in a directed acyclic graph (DAG) in a computer network, a low-contact node in the DAG;

identifying neighbors of the low-contact node;

establishing a multicast tree from the particular node to the low-contact node through a plurality of the neighbors to reach the low-contact node; and

sending traffic from the particular node to the low-contact node as multicast traffic on the multicast tree, wherein each of the plurality of neighbors attempts to forward the traffic to the low-contact node.

2. The method as in claim 1, wherein the low-contact node is identified as a node that is at risk of having an invalid path when attempts are made to reach the low-contact node.

3. The method as in claim 1, wherein the low-contact node is identified as one of either a node not participating in keep-alive message transmission or a node infrequently transmitting traffic.

4. The method as in claim 1, wherein determining the low-contact node comprises:

receiving an indication from the low-contact node that the low-contact node is a low-contact node.

5. The method as in claim 4, wherein the indication comprises a list of neighbors of the low-contact node, and where identifying the neighbors comprises:

examining the indication from the low-contact node to identify the neighbors of the low-contact node.

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

informing the low-contact node of a multicast group corresponding to the multicast tree.

7. The method as in claim 1, wherein establishing the multicast tree comprises:

ensuring path diversity where available within the DAG.

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

receiving a request from the low-contact node for path diversity within the multicast tree.

9. The method as in claim 1, wherein the particular node is a root node of the DAG.

10. The method as in claim 1, wherein sending comprises sending all traffic to the low-contact node as multicast traffic on the multicast tree.

11. An apparatus, comprising:

one or more network interfaces;

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;

identify a low-contact node in a directed acyclic graph (DAG) in a computer network;

identify neighbors of the low-contact node;

establish a multicast tree to the low-contact node through a plurality of the neighbors to reach the low-contact node; and

send traffic to the low-contact node as multicast traffic on the multicast tree, wherein each of the plurality of neighbors attempts to forward the traffic to the low-contact node.

12. The apparatus as in claim 11, wherein the process when executed is further operable to identify the low-contact node as a node that is at risk of having an invalid path when attempts are made to reach the low-contact node.

13. The apparatus as in claim 11, wherein the process when executed is further operable to identify the low-contact node through receipt of an indication from the low-contact node that the low-contact node is a low-contact node.

14. The apparatus as in claim 13, wherein the indication comprises a list of neighbors of the low-contact node.

15. A method, comprising:

determining, by a node in a directed acyclic graph (DAG) in a computer network, a status of the node as a low-contact node in the DAG;

identifying neighbors of the low-contact node;

transmitting an indication that the node is a low-contact node to a root node of the DAG, the indication having a list of the identified neighbors of the low-contact node; and

receiving traffic from one or more of the neighbors as multicast traffic.

16. The method as in claim 15, wherein the status as the low-contact node is identified based on the node being at risk of having an invalid path when attempts are made to reach the low-contact node.

17. The method as in claim 15, wherein the status as the low-contact node is identified based on the node not participating in keep-alive message transmission.

18. The method as in claim 15, wherein identifying the neighbors comprises:

transmitting a discovery message from the node;

receiving replies from the neighbors; and

identifying the neighbors based on the replies.

19. The method as in claim 15, further comprising:

updating the neighbors based on from which neighbors the multicast traffic is received.

20. The method as in claim 19, wherein updating comprises:

identifying a list of neighbors from which traffic was expected to arrive;

comparing the neighbors from which the traffic is received to the list of expected neighbors;

identifying neighbors within the list from which traffic has not arrived; and

modifying route tables of the low-contact node to remove the neighbors from which traffic has not arrived.

21. The method as in claim 15, further comprising:

requesting, within the indication, path diversity within a multicast tree corresponding to the multicast traffic.

22. The method as in claim 15, further comprising:

receiving identification of a multicast group corresponding to the multicast traffic from the root; and

joining the multicast group by the low-contact node.

23. The method as in claim 15, further comprising:

receiving duplicate multicast traffic from the neighbors; and

in response, ignoring all but a first received multicast traffic.

24. The method as in claim 15, wherein the low-contact node is a wireless node.

25. The method as in claim 15, wherein receiving traffic from one or more of the neighbors as multicast traffic comprises one of either:

receiving traffic from one or more of the neighbors as a multicast packet from each of the one or more of the neighbors;

or

receiving traffic from one or more of the neighbors as a unicast packet decapsulated from multicast traffic from each of the one or more of the neighbors.

26. An apparatus, comprising:

one or more network interfaces adapted to communicate in a directed acyclic graph (DAG) 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 status of the apparatus as a low-contact node in the DAG;

identify neighbors of the low-contact node;

transmit an indication that the apparatus is a low-contact node to a root node of the DAG, the indication having a list of the identified neighbors of the low-contact node; and

receive traffic from one or more of the neighbors as multicast traffic.