Methods, systems, and computer program products for inhibiting message traffic to an unavailable terminating SIP server

• US 20080056234A1
• Filed: 08/25/2006
• Published: 03/06/2008
• Est. Priority Date: 08/04/2006
• Status: Active Grant

• Current Assignee: Tekelec, Inc. (Oracle Corporation)
• Original Assignee: Tekelec
• Inventors: Sprague, David M.
• Granted Patent: US 7,929,419 B2
• Time in Patent Office: Days
• US Class Current: 370/352
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 65/1016 IP multimedia subsystem [IMS]
• CPC Class Codes: H04L 65/1045 Proxies, e.g. for session initiation protocol [SIP]
• CPC Class Codes: H04L 65/1046 Call controllers; Call servers
• CPC Class Codes: H04L 67/1034 Reaction to server failures by a load balancer
• 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

Methods, systems, and computer program products for inhibiting message traffic to an unavailable terminating SIP server are disclosed. According to one method, at least one list of SIP servers accessible by a call session control function (CSCF) is maintained at an originating CSCF. The list includes at least one of availability and unavailability status information for the terminating SIP servers. A request is received to contact a destination via a one of the terminating SIP servers. The list is indexed and a first terminating SIP server is identified. If the first terminating SIP server is determined to be unavailable based on information in the list, a second terminating SIP server is identified using the list.

Claims

1. A method for forwarding or inhibiting message traffic to a terminating session initiation protocol (SIP) server using a SIP server exception list, the method comprising:

at an originating call session control function (CSCF);

(a) maintaining at least one list of terminating SIP servers accessible by the CSCF, the list including at least one of availability and unavailability information for the terminating SIP servers;

(b) receiving a request to contact a destination accessible via one of the terminating SIP servers;

(c) indexing the list and identifying a first terminating SIP server;

(d) determining whether the destination SIP server is available using information stored in the list; and

(e) in response to determining that the first terminating SIP server is not available, identifying a second terminating SIP server using the list.

2. The method of claim 1 wherein maintaining at least one list includes maintaining a first list including available and unavailable SIP servers accessible by the CSCF and a second list including unavailable SIP servers accessible by the CSCF.

3. The method of claim 1 wherein maintaining at least one list includes maintaining a single list containing available and unavailable SIP servers accessible the CSCF.

4. The method of claim 1 wherein maintaining at least one list includes building a list including availability and unavailability status information for the SIP servers based on communications involving the SIP servers.

5. The method of claim 1 wherein maintaining at least one list includes marking a SIP server entry in the list as unavailable in response to failing to receive a response from the corresponding server to a query message to the server within a timeout period, the timeout period being less than that for SIP call processing.

6. The method of claim 1 wherein maintaining at least one list includes sending a query to a SIP server, obtaining a response from the SIP server including status information, and storing the status from the query in the list.

7. The method of claim 1 wherein maintaining at least one list includes maintaining a retry timer for an entry identifying a server as unavailable and removing unavailability status from the entry in response to expiration of the retry timer.

8. The method of claim 1 wherein indexing a list includes randomly indexing a list.

9. The method of claim 1 wherein indexing a list includes indexing a list according to a predetermined order of preference.

10. The method of claim 1 comprising, in response to the first terminating SIP server being available forwarding a SIP request message to the first terminating SIP server.

11. A method for load balancing communications among terminating SIP servers, the method comprising:

(a) receiving a first SIP request message including a domain name;

(b) in response to the first SIP request message, resolving the domain name into a list of terminating SIP servers having a first order of preference for contacting the terminating SIP servers;

(c) receiving second SIP request message including the domain name;

(d) in response to the second SIP request message, resolving the domain into a list of the terminating SIP servers having a second order of preference for contacting the terminating SIP servers; and

(e) forwarding the first and second SIP request messages to terminating SIP servers in accordance with the first and second orders of preference.

12. A system for forwarding or inhibiting message traffic to a terminating session initiation protocol (SIP) server, the system comprising:

a call session control function (CSCF), the CSCF including;

(a) a terminating SIP server database for storing at least one list of terminating SIP servers and at least one of availability and unavailability status information for the terminating SIP servers; and

(b) a SIP communications routing module for receiving a SIP request message, for accessing the terminating SIP server database, for identifying a first terminating SIP server and status of the first terminating SIP server, and in response to determining that the first terminating SIP server is unavailable, for identifying a second terminating SIP server to which the SIP request message should be forwarded.

13. The system of claim 12 wherein the terminating SIP server database includes a first list of available SIP servers and a second list of unavailable SIP servers.

14. The system of claim 12 wherein the terminating SIP server database includes a single list storing available and unavailable SIP server information.

15. The system of claim 12 wherein the SIP communications routing module is adapted to build the terminating SIP server database based on information received from the terminating SIP servers in response to SIP request messages.

16. The system of claim 12 wherein the SIP communications routing module is adapted to mark a SIP server in the terminating SIP server database as unavailable in response to a timeout expiring for a SIP request message transmitted by the SIP communications routing module, the timeout being less than a SIP call processing timeout.

17. The system of claim 12 wherein the SIP communications routing module is adapted to mark an entry in the terminating SIP server database as unavailable in response to receiving a message from a terminating SIP server indicating unavailability of the terminating SIP server.

18. The system of claim 12 wherein the SIP communications routing module is adapted to maintain a retry interval for SIP servers marked as unavailable in the terminating SIP server database and to remove unavailability status regarding the SIP servers marked as unavailable in response to expiration of the retry interval for each entry.

19. The system of claim 12 wherein the SIP communications routing module is adapted to randomly index a list of terminating servers in the terminating SIP server database to determine a server to which a message should be forwarded.

20. The system of claim 12 wherein the SIP communications routing module is adapted to access the terminating SIP server database in a predetermined order of preference specified by a domain name system (DNS) server.

21. The system of claim 12 wherein the SIP communications routing module is adapted to route the message to the first terminating SIP server in response to determining availability of the first terminating SIP server using the terminating SIP server database.

22. A computer program product comprising computer executable instructions embodied in a computer readable medium for performing steps comprising:

at an originating call session control function (CSCF);

(a) maintaining at least one list of terminating SIP servers accessible by the CSCF, the list including at least one of availability and unavailability information for the terminating SIP servers;

(b) receiving a request to contact a destination accessible via one of the terminating SIP servers;

(c) indexing the list and identifying a first terminating SIP server;

(d) determining whether the destination SIP server is available using information stored in the list; and

(e) in response to determining that the first terminating SIP server is not available, identifying a second terminating SIP server using the list.

23. The computer program product of claim 22 wherein maintaining at least one list includes maintaining a first list including available and unavailable SIP servers accessible by the CSCF and a second list including unavailable SIP servers accessible by the CSCF.

24. The computer program product of claim 22 wherein maintaining at least one list includes maintaining a single list containing available and unavailable SIP servers accessible the CSCF.

25. The computer program product of claim 22 wherein maintaining at least one list includes building a list including availability and unavailability status information for the SIP servers based on communications involving the SIP servers.

26. The computer program product of claim 22 wherein maintaining at least one list includes marking a SIP server entry in the list as unavailable in response to failing to receive a response from the corresponding server to a query message to the server within a timeout period, the timeout period being less than that for SIP call processing.

27. The computer program product of claim 22 wherein maintaining at least one list includes sending a query to a SIP server, obtaining a response from the SIP server including status information, and storing the status from the query in the list based on the query.

28. The computer program product of claim 22 wherein maintaining at least one list includes maintaining a retry timer for an entry identifying a server as unavailable and removing unavailability status from the entry in response to expiration of the retry timer.

29. The computer program product of claim 22 wherein indexing a list includes randomly indexing a list.

30. The computer program product of claim 22 wherein indexing a list includes indexing a list according to a predetermined order of preference.

31. The computer program product of claim 22 comprising, in response to the first terminating SIP server being available, forwarding a SIP request message to the first terminating SIP server.

32. A computer program product comprising computer executable instructions embodied in a computer readable medium for performing steps comprising:

(a) receiving a first SIP request message including a domain name;

(b) in response to the first SIP request message, resolving the domain name into a list of terminating SIP servers having a first order of preference for the terminating SIP servers;

(c) receiving second SIP request message including the domain name;

(d) in response to the second SIP request message, resolving the domain into a list of the terminating SIP servers having a second order of preference for the terminating SIP servers; and

(e) forwarding the first and second SIP request messages to terminating SIP servers in accordance with the first and second orders of preference.