Method and apparatus for maintaining active calls during failover of network elements

• US 8,593,939 B2
• Filed: 04/19/2005
• Issued: 11/26/2013
• Est. Priority Date: 04/19/2005
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Inventors: Croak, Marian, Eslambolchi, Hossein
• Primary Examiner(s): Nguyen, Duc
• Assistant Examiner(s): GAY, SONIA L
• Application Number:
  US11/109,120
• Publication Number:
  US 20060250946A1
• Time in Patent Office: 3,143 Days
• Field of Search: 379/221.01, 379/221.03, 379/221.04, 379/112.02, 379/9, 370216-228, 370351-356, 714/114
• US Class Current: 370/216
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/1104 Session initiation protocol [SIP]
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

A method and apparatus for keeping transitory state in a packet network so that in the event of a failover of a network element, existing active calls can be quickly re-established by the packet network or briefly held in a suspended state until the affected network element returns to a healthy state is disclosed.

Claims

1. A method for maintaining active calls during a failover in a communication network, comprising:

suspending, by a processor of an active network element, all of the active calls between a plurality of calling endpoints and a plurality of called endpoints in the active network element where the active calls are placed in a suspended active state;

transferring, by the processor of the active network element, call states of the active calls in the suspended active state in the active network element to a standby network element when the failover relates to the active network element; and

switching over, by the processor of the active network element, the active calls in the suspended active state to the standby network element by activating the transferred call states of the active calls in the suspended active state where the active calls are supported by the standby network element between the plurality of calling endpoints and the plurality of called endpoints, wherein the active network element comprises an active border element and the standby network element comprises a standby border element, wherein if the transferring and the switching fail to complete within a pre-specified period of time, the active calls are dropped.

2. The method of claim 1, wherein the communication network is an internet protocol network.

3. The method of claim 1, wherein the transferring comprises:

keeping the active calls in the suspended active state.

4. The method of claim 1, wherein the transferring the call states is initiated by an active network element failure event.

5. The method of claim 1, wherein the activating comprises:

modifying the active calls from the suspended active states to active states.

6. The method of claim 1, wherein the switching over the active calls to the standby network element comprises:

modifying a current media path of the active calls to a new media path to pass through the standby network element.

7. A non-transitory computer readable medium a plurality of instructions which, when executed by a processor of an active network element, cause the processor to perform operations for maintaining active calls during a failover in a communication network, the operations comprising:

suspending all of the active calls between a plurality of calling endpoints and a plurality of called endpoints in the active network element so that where the active calls are placed in a suspended active state;

transferring call states of the active calls in the suspended active state in the active network element to a standby network element when the failover relates to the active network element; and

switching over the active calls in the suspended active state to the standby network element by activating the transferred call states of the active calls in the suspended active state where the active calls are supported by the standby network element between the plurality of calling endpoints and the plurality of called endpoints, wherein the active network element comprises an active border element and the standby network element comprises a standby border element, wherein if the transferring and the switching fail to complete within a pre-specified period of time, the active calls are dropped.

8. The non-transitory computer readable medium of claim 7, wherein the communication network is an Internet protocol network.

9. The non-transitory computer readable medium of claim 7, wherein the transferring comprises:

keeping the active calls in the suspended active state.

10. The non-transitory computer readable medium of claim 7, wherein the transferring the call states is initiated by an active network element failure event.

11. The non-transitory computer readable medium of claim 7, wherein the activating comprises:

modifying the active calls from the suspended active states to active states.

12. The non-transitory computer readable medium of claim 7, wherein the switching over the active calls to the standby network element comprises:

modifying a current media path of the active calls to a new media path to pass through the standby network element.

13. An apparatus for maintaining active calls during a failover in a communication network, comprising:

a processor of an active network element; and

a non-transitory computer readable medium storing a plurality of instructions which, when executed by the processor, cause the processor to perform operations, the operations comprising;

suspending all of the active calls between a plurality of calling endpoints and a plurality of called endpoints in the active network element where the active calls are placed in a suspended active state;

transferring call states of the active calls in the suspended active state in the active network element to a standby network element when the failover relates to the active network element; and

switching over the active calls in the suspended active state to the standby network element by activating the transferred call states of the active calls in the suspended active state where the active calls are supported by the standby network element between the plurality of calling endpoints and the plurality of called endpoints, wherein the active network element comprises an active border element and the standby network element comprises a standby border element, wherein if the transferring and the switching fail to complete within a pre-specified period of time, the active calls are dropped.

14. The apparatus of claim 13, wherein the communication network is an internet protocol network.

15. The apparatus of claim 13, wherein the transferring keeps the active calls in the suspended active state.

16. The apparatus of claim 13, wherein the transferring the call states is initiated by an active network element failure event.

17. The apparatus of claim 13, wherein the activating comprises:

modifying the active calls from the suspended active states to active states.

18. The apparatus of claim 13, wherein the switching modifies a current media path of the active calls to a new media path to pass through the standby network element.