Methods and apparatus for improving resiliency of communication networks

• US 20040071090A1
• Filed: 07/14/2003
• Published: 04/15/2004
• Est. Priority Date: 07/15/2002
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Park, Vincent, Corson, M. Scott, Laroia, Rajiv, Kapoor, Samir, Stephens, Arthur
• Granted Patent: US 8,036,104 B2
• Time in Patent Office: Days
• US Class Current: 370/244
• CPC Class Codes: G06F 11/0709 in a distributed system consisting of a plurality of standalone computer nodes, e.g. clusters, client-server systems
• CPC Class Codes: G06F 11/079 Root cause analysis, i.e. error or fault diagnosis in a hardware test environment G06F11/22; in a software test environment G06F11/36
• CPC Class Codes: H04L 41/0213 Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/0663 Performing the actions predefined by failover planning, e.g. switching to standby network elements
• CPC Class Codes: H04L 41/5012 determining service availability, e.g. which services are available at a certain point in time

Abstract

Techniques for supporting fault tolerance in communications systems, e.g., cellular communications networks with mobile wireless user devices, are described. In various embodiments end nodes, e.g., mobile devices, store information indicating which other nodes are critical to their operation, e.g., critical to messages and/or signals being properly routed to the individual end node. Different network nodes may be critical to different end nodes. Critical node information stored by an end node may be statically preprogrammed or dynamically generated, or may include a combination of both and static and dynamic information. In some embodiments at least a portion of the information used to determine which nodes are critical to a particular end node is generated dynamically from signaling information, e.g., session control signaling, transmitted and/or received during normal operation of the end node. Faults, failures and/or scheduled outages in various network nodes are detected and/or reported. Fault notification messages are communicated, e.g., broadcast, to nodes, e.g., end nodes, which may be affected by a detected/reported service disruption. End nodes receiving a fault notification message determine if the message indicates a disruption in a node that is critical to the end node receiving the message. If the indicated disruption is in a critical node, the end node takes action to ameliorate the effect of the reported condition, e.g., the end node may initiate a registration operation with a new session signaling server in response to an indicated fault associated with the session signaling server with which the end node was registered. Fault notification messages indicating disruptions in nodes which are not critical to the end node receiving the fault notification message may be ignored once it is determined that the indicated disruption is in a node which is not critical to the end node receiving the message. The invention described herein minimizes service disruption following fault, failure or outage of critical network nodes, improving overall system robustness and resiliency.

Claims

1. A communications method for use in a communications system including at least one network node and one end node, the method comprising:

operating an end node to receive a fault signal indicating a network node fault;

determining if the network node fault corresponds to a network node that is important to routing of signals to or from said end node; and

if it is determined that the network node fault corresponds to a network node that is important to routing of signals to or from said end node, operating the end node to initiate an operation to ameliorate the effect of the network node fault on said end node.

2. The method of claim 1, wherein said step of determining if the network node fault corresponds to a network node that is important to routing of signals to or from said end node includes:

comparing network node information included in the received fault signal to stored information identifying at least one network node important to routing of signals to or from said end node.

3. The method of claim 2, further comprising:

determining said operation to ameliorate the effect of the network node fault as a function of information stored in said end node, said stored information relating to a plurality of possible operations.

4. The method of claim 3, wherein said step of determining said operation to ameliorate the effect of the network node fault is also performed as a function of the network node at which the fault occurred with said operation being selected from a plurality of possible operations based on both the type of fault and which one of a plurality of network nodes was the node at which the fault occurred.

5. The method of claim 2, wherein said stored information identifying at least one network node important to routing of signals to or from said end node includes:

a list of network nodes important to the routing of signals to said end node.

6. The method of claim 5, wherein said stored information includes information identifying a network node which is used by said end node as at least one of a Mobile IP home agent, a Session Initiation Protocol proxy server, and a Session Initiation Protocol location registrar.

7. The method of claim 5, wherein said stored information includes information identifying a network node which is used by said end node as an access node through which said end node is coupled to other nodes in the communications network.

8. The method of claim 7, wherein the access node is a base station and wherein said end node is a mobile device that is coupled to said base station by a wireless communications link.

9. The method of claim 2, further comprising the step of:

dynamically generating at least a portion of said stored information identifying network nodes important to routing of signals to or from said end node from information included in signals sent to or from said end node.

10. The method of claim 9, wherein said step of dynamically generating at least a portion of said stored information identifying network nodes includes:

operating the end node to monitor for non-fault related signals and to generate at least some of said stored information from the monitored non-fault related signals.

11. The method of claim 10, wherein said non-fault related signals include session signaling messages communicated to or from said end node.

12. The method of claim 10, wherein said non-fault related signals are routing messages.

13. The method of claim 1, wherein said operation to ameliorate the effect of the network fault on said end node is a Mobile IP registration operation.

14. The method of claim 1, wherein said operation to ameliorate the effect of the network fault on said end node is an end node state update operation.

15. The method of claim 1, further comprising the steps of:

sending a status request signal from a first network node to a second network node;

receiving a response to said status request signal; and

sending a network node fault signal to said end node when said response indicates a fault condition.

16. The method of claim 1, further comprising the steps of:

periodically sending a status request signal from a first network node to a second network node; and

sending a network node fault signal to said end node when a response to at least one of said periodically received status request signals is not received.

17. The method of claim 16, further comprising the steps of:

maintaining a count of the number of consecutive status request signals sent to said second node for which a response is not received; and

wherein said sending a network node fault signal is performed in response to determining that said maintained count at least equals a threshold number.

18. The method of claim 1, further comprising the steps of:

receiving a fault signal at a first network node; and

sending a network node fault signal to said end node in response to receiving a fault signal.

19. The method of claim 18, wherein said step of sending a network node fault signal includes periodically sending fault signals to a plurality of end nodes at preselected time intervals.

20. The method of claim 19, further comprising:

operating at least some of said plurality of end nodes to monitor for fault signals at said preselected time intervals but not between said preselected time intervals.

21. The method of claim 20, wherein said fault signals are messages, each message including at least one IP packet.

22. The method of claim 1, wherein said fault signal is a multicast signal, the method further comprising:

operating a plurality of additional end nodes to receive said fault signal; and

operating each of the additional end nodes, in said plurality of additional end nodes, to determine if the network node fault corresponds to a network node that is important to routing of messages to or from said additional end node.

23. The method of claim 22, further comprising:

operating each additional end node which determines that the network node fault corresponds to a network node that is important to routing of messages to or from said additional end node, to initiate an operation to ameliorate the effect of the network node fault on said additional end node.

24. The method of claim 22, wherein each of said plurality of additional end nodes monitors for said fault signal at periodic scheduled times.

25. A communications method for use in a communications system including at least one network node and one end node, the method comprising:

operating an end node to receive a service interference notification signal indicating interference with service at a network node;

determining if the indicated service interference corresponds to a network node that is critical to said end node; and

if it is determined that the indicated network node service interference corresponds to a network node that is critical to said end node, operating the end node to initiate an operation to ameliorate the effect of the indicated network node service interference on said end node.

26. The communications method of claim 25, wherein said service interference notification signal is a fault message indicating a service outage at said network node due to a network node fault.

27. The method of claim 26, wherein said step of determining if the indicated service interference corresponds to a network node that is critical to said end node includes:

comparing network node information included in the received message to stored information identifying network nodes critical to said end node.

28. The method of claim 27, wherein a network node is critical to said end node if said network node is necessary for proper routing of at least some signals to said end node.

29. The method of claim 25, wherein said step of determining said operation to ameliorate the effect of the indicated network node service interference includes accessing stored information listing a plurality of operations and selecting from the plurality of possible operations the operation to be performed based on both the type of fault and which one of a plurality of network nodes was the indicated network node at which the fault occurred.

30. The method of claim 29, wherein said stored information includes information identifying a network node which is used by said end node as at least one of a Mobile IP home agent, a Session Initiation Protocol proxy server and a Session Initiation Protocol location registrar.

31. The method of claim 25, wherein said end node is a mobile node connected by a wireless communications link to an access node that is coupled to said indicated network node, said mobile node including a stored list of critical nodes and actions to be taken to ameliorate the effect of faults at said listed critical nodes.

32. The method of claim 31, further comprising:

generating at least a portion of said stored information identifying network nodes from at least one of a Mobile IP agent solicitation message, Mobile IP agent advertisement message, Mobile IP registration message and a Mobile IP registration reply message communicated between said end node and said access node over the wireless communications link.

33. The method of claim 29, further comprising the step of:

dynamically generating at least a portion of said stored information identifying network nodes critical to said end node from information included in signals sent to or from said end node.

34. The method of claim 25, wherein said operation to ameliorate the effect of the network fault on said end node is a Mobile IP registration operation.

35. The method of claim 25, further comprising:

operating said end node to monitor for service interference signals at preselected time intervals but not between said preselected time intervals.

36. The method of claim 25, wherein said service interference signal is a multicast signal, the method further comprising:

operating a plurality of additional end nodes to receive said service interference notification signal; and

operating each of the additional end nodes, in said plurality of additional end nodes, to determine if the indicated network node service interference corresponds to a network node that is important to routing of messages to or from said additional end node.

37. The method of claim 36, further comprising:

operating each additional end node which determines that the service interference notification signal corresponds to a network node that is important to routing of messages to or from said additional end node, to initiate an operation to ameliorate the effect of the service interference on said additional end node.

38. The communications method of claim 25, wherein said service interference notification signal is a message indicating a scheduled service outage at said network node.

40. The communications device of claim 38,

wherein said device is a portable device;

and

wherein said receiver circuitry includes a radio receiver circuit.

41. The communications device of claim 40, further comprising:

means for controlling the communications device to monitor for said service interference notification messages at preselected intervals but not between said preselected time intervals.

42. The communications device of claim 40, wherein said set of stored information includes information identifying a network node which is used by said end node as at least one of a Mobile IP home agent, a Session Initiation Protocol proxy server and a Session Initiation Protocol location registrar.

43. The communications device of claim 42, further comprising:

means for generating at least a portion of said set of stored information indicating network nodes which are necessary to proper routing of signals from at least one of a Mobile IP signal and a Session Initiation Protocol signal.

44. The communications device of claim 43, wherein said communications device is a mobile node connected by a wireless communications link to an access node that is coupled to said indicated network node, said set of stored information including actions to be taken to ameliorate the effect of faults at network nodes which are necessary to proper routing of IP packets to said mobile node.

45. The communications device of claim 44, wherein one of said actions to be taken to ameliorate the effect of faults at network nodes is a Mobile IP registration operation.

39. A communications device, comprising:

memory including a set of stored information indicating network nodes which are necessary to proper routing of signals either to said communications device or from said communications device to other network nodes;

receiver circuitry for receiving messages from network nodes including service interference notification messages indicating service interference at a network node; and

means for processing received service interference notification messages to determine if service interference indicated by a received network service interference notification message indicates service interference at a network node necessary to proper routing of signals either to said communications device or from said communications device to another network node.