Failsafe recovery facility in a coordinated timing network

• US 7,925,916 B2
• Filed: 04/10/2008
• Issued: 04/12/2011
• Est. Priority Date: 04/10/2008
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dahlen, Dennis J., Crabtree, Donald, Sevigny, Denise M., Carlson, Scott M., Wierbowski, Judith A.
• Primary Examiner(s): Iqbal; Nadeem
• Application Number:
  US12/100,660
• Publication Number:
  US 20090259881A1
• Time in Patent Office: 1,097 Days
• Field of Search: 714 1- 4, 714 11- 13, 714/15, 714/16, 714 18- 21, 714/31, 714/37, 714/39, 714/43, 714/47, 714/48, 714/56
• US Class Current: 714/4.1
• CPC Class Codes: H04J 3/0688 Change of the master or reference, e.g. take-over or failure of the master
• CPC Class Codes: H04L 41/0654 using network fault recovery ring fault isolation or reconfiguration in loop networks without recovery actions by a network management system H04L12/437
• CPC Class Codes: H04L 43/0817 by checking functioning
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• 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 failsafe recovery capability for a Coordinated Timing Network. The recovery capability facilitates recovery when communication is lost between two servers of the coordinated timing network. The capability includes checking another system'"'"'s status in order to determine what action is to be taken. The status includes the stratum level of the servers and a version number indicating the code level of the servers.

Claims

1. A computer program product for facilitating recover in a timing network, the computer program product comprising:

a tangible storage medium readable by a processor and storing instructions for execution by the processor for performing a method comprising;

detecting, by one server of the timing network, a communication failure situation in the timing network for which corrective action is to be taken, said communication failure situation excluding a failure of the one server and another server of the timing network coupled to the one server;

obtaining, in response to the detecting the communication failure situation, status information of the another server of the timing network, said status information comprising a stratum level of the another server and a level of capability of the another server; and

selecting a corrective action to be taken, said selecting being based on the communication failure situation, the obtained status information, and a stratum level and a level of capability of the one server.

2. The computer program product of claim 1, wherein in performing the selected corrective action at least part of the timing network remains in timing synchronization.

3. The computer program product of claim 1, wherein the selected corrective action maintains data integrity within the timing network.

4. The computer program product of claim 1, wherein the level of capability of the one server comprises at least one version of a timing protocol associated with the one server, the level of capability of the another server comprises at least one version of a timing protocol associated with the another server, and wherein the level of capability of the one server is different from the level of capability of the another server.

5. The computer program product of claim 4, wherein the level of capability includes aspects related to Server Time Protocol timing, including at least one of recovery, configuration, timing management, formatting of time synchronization messages and time of day clock synchronization.

6. The computer program product of claim 1, wherein the communication failure situation comprises one of:

the one server and the another server being at a stratum-0 level;

or

the one server and the another server being at a stratum-1 level.

7. The computer program product of claim 1, wherein the detecting comprises:

requesting, by the one server, operational status of the another server, said requesting including a request that comprises the stratum level and the level of capability of the one server;

attempting, by a console coupled to the one server, to communicate with a console of the another server;

forwarding, in response to a successful attempt, the stratum level and the level of capability of the one server to a console of the another server;

determining, by the console of the another server, whether the another server is in a failed state; and

wherein the obtaining the status information is performed in response to determining that the another server is not in the failed state.

8. The computer program product of claim 7, wherein the obtaining comprises:

requesting by the console of the another server exchange of server state;

providing, by the console of the another server to the console of the one server, the stratum level and level of capability of the one server and the another server; and

forwarding, from the console of the one server to the one server, the stratum level and the level of capability of the one server and the another server.

9. The computer program product of claim 8, wherein the selecting is performed by the one server or the another server depending on the communication failure situation and the stratum level and level of capability of the one server and the another server.

10. The computer program product of claim 1, wherein the detecting comprises:

determining that a system check signal has been issued;

deciding whether the system check signal can be interpreted as a failure of the another server of the timing network; and

invoking a console assisted recovery procedure to determine the communication failure situation, in response to deciding that the system check signal cannot be interpreted as a failure of the another server.

19. The computer program product of claim 1, wherein the timing network comprises a timing network link between the one server and the another server, and wherein the communication failure situation comprises a loss in timing network link communication.

20. The computer program product of claim 19, wherein the timing network further comprises a console communication path, separate from the timing network link, coupling the one server and the another server and allowing the one server and the another server to communicate across the console communication path, and wherein the obtaining is via the console communication path.

11. A method of facilitating recovery in a timing network, said method comprising:

detecting, by one server of the timing network, a communication failure situation in the timing network for which corrective action is to be taken, said communication failure situation excluding a failure of the one server and another server of the timing network coupled to the one server;

obtaining, in response to the detecting the communication failure situation, status information of the another server of the timing network, said status information comprising a stratum level of the another server and a level of capability of the another server; and

selecting a corrective action to be taken, said selecting being based on the communication failure situation, the obtained status information, and a stratum level and a level of capability of the one server.

12. The method of claim 11, wherein the detecting comprises:

requesting, by the one server, operational status of the another server, said requesting including a request that comprises the stratum level and the level of capability of the one server;

attempting, by a console coupled to the one server, to communicate with a console of the another server;

forwarding, in response to a successful attempt, the stratum level and the level of capability of the one server to a console of the another server;

determining, by the console of the another server, whether the another server is in a failed state; and

wherein the obtaining the status information is performed in response to determining that the another server is not in the failed state.

13. The method of claim 12, wherein the obtaining comprises:

requesting by the console of the another server exchange of server state;

providing, by the console of the another server to the console of the one server, the stratum level and level of capability of the one server and the another server; and

forwarding, from the console of the one server to the one server, the stratum level and the level of capability of the one server and the another server.

14. The method of claim 11, wherein the detecting comprises:

determining that a system check signal has been issued;

deciding whether the system check signal can be interpreted as a failure of the another server of the timing network; and

invoking a console assisted recovery procedure to determine the communication failure situation, in response to deciding that the system check signal cannot be interpreted as a failure of the another server.

15. A computer system for facilitating recovery in a timing network, said computer system comprising:

a memory; and

a processor in communications with the memory, wherein the computer system is configured to perform a method, said method comprising;

detecting, by one server of the timing network, a communication failure situation in the timing network for which corrective action is to be taken, said communication failure situation excluding a failure of the one server and another server of the timing network coupled to the one server;

obtaining, in response to the detecting the communication failure situation, status information of the another server of the timing network, said status information comprising a stratum level of the another server and a level of capability of the another server; and

selecting a corrective action to be taken, said selecting being based on the communication failure situation, the obtained status information, and a stratum level and a level of capability of the one server.

16. The computer system of claim 15, wherein the level of capability includes aspects related to Server Time Protocol timing, including at least one of recovery, configuration, timing management, formatting of time synchronization messages and time of day clock synchronization.

17. The computer system of claim 15, wherein the detecting comprises:

requesting, by the one server, operational status of the another server, said requesting including a request comprising the stratum level and the level of capability of the one server;

attempting, by a console coupled to the one server, to communicate with a console of the another server;

forwarding, in response to a successful attempt, the stratum level and the level of capability of the one server to a console of the another server;

determining, by the console of the another server, whether the another server is in a failed state; and

wherein the obtaining the status information is performed in response to determining that the another server is not in the failed state.

18. The computer system of claim 17, wherein the obtaining comprises:

requesting by the console of the another server exchange of server state;

providing, by the console of the another server to the console of the one server, the stratum level and level of capability of the one server and the another server; and

forwarding, from the console of the one server to the one server, the stratum level and the level of capability of the one server and the another server.