ESTABLISHING A LOGICAL PATH BETWEEN SERVERS IN A COORDINATED TIMING NETWORK

• US 20080183877A1
• Filed: 10/22/2007
• Published: 07/31/2008
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dahlen, Dennis J., Carlson, Scott M., Errickson, Richard K.
• Granted Patent: US 7,797,414 B2
• Time in Patent Office: Days
• US Class Current: 709/228
• CPC Class Codes: G06F 1/12 Synchronisation of different clock signals provided by a plurality of clock generators
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

A technique for establishing a logical path between two servers in a coordinated timing network of a processing environment is provided. The technique includes the exchange of command and response message pairs by a server and an attached server, via a physical link. The server transmits a command message to an attached server to establish a server-time-protocol (STP) logical path and receives a response from the attached server. The technique also includes the server receiving a request transmitted by the attached server to establish an STP logical path to the server and transmitting a response to the attached server'"'"'s request. A logical path between the server and the attached server is established if the attached server'"'"'s response indicates that the server'"'"'s request was accepted by the attached server and if the server'"'"'s response indicates that the attached server'"'"'s request was accepted by the server.

Claims

1. At least one program storage device readable by a machine embodying at least one program of instructions executable by the machine to perform a method of establishing a logical path between two processing systems in a coordinated timing network of a processing environment, the method comprising:

transmitting, by a processing system to an attached processing system, a request to establish a logical path between the processing system and the attached processing system, the logical path facilitating time synchronization of the processing system and the attached processing system;

receiving, by the processing system, a response from the attached processing system indicating whether the attached processing system accepted the request transmitted by the processing system;

receiving, by the processing system, another request transmitted by the attached processing system, the another request requesting to establish the logical path between the processing system and the attached processing system;

transmitting, by the processing system to the attached processing system, another response indicating whether the processing system accepted the another request transmitted by the attached processing system; and

establishing the logical path between the processing system and the attached processing system if the response indicates that the request was accepted by the attached processing system and if the another response indicates that the another request was accepted by the processing system.

2. The at least one program storage device of claim 1, wherein the processing system comprises a server, and wherein the attached processing system comprises an attached server.

3. The at least one program storage device of claim 1, wherein the method further comprises:

detecting whether a data communication link has been reconfigured since the logical path was established on the data communication link; and

initiating the transmitting, by a processing system to an attached processing system, of the request to re-establish the logical path if the data communication link has been reconfigured.

4. The at least one program storage device of claim 1, wherein the method further comprises:

determining whether the attached processing system has failed to respond to a command to exchange time parameters with the processing system within a pre-determined period of time; and

initiating the transmitting, by the processing system to the attached processing system, of the request to establish the logical path if the attached processing system has failed to respond to the command to exchange time parameters.

5. The at least one program storage device of claim 1, wherein the method further comprises:

comparing a coordinated timing network (CTN) identification (ID) parameter value of the processing system and a CTN ID parameter value of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the CTN ID parameter value of the processing system differs from the CTN ID parameter value of the attached processing system.

6. The at least one program storage device of claim 1, wherein the method further comprises:

comparing a system identification parameter value of the processing system and a system identification parameter value of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the system identification parameter value of the processing system is identical to the system identification parameter value of the attached processing system.

7. The at least one program storage device of claim 1, wherein the method further comprises:

comparing a version number parameter value of a time protocol facility of the processing system and a version number parameter value of a time protocol facility of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the comparing indicates that the processing system'"'"'s time protocol facility is not compatible with the attached processing system'"'"'s time protocol facility.

8. The at least one program storage device of claim 1, wherein the method further comprises:

comparing a configuration block of a time protocol facility of the processing system and a configuration block of a time protocol facility of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the comparing indicates that the processing system'"'"'s time protocol facility is not compatible with the attached processing system'"'"'s time protocol facility.

9. The at least one program storage device of claim 8, wherein the configuration block comprises a stratum-1 configuration block.

10. A processing system for a coordinated timing network of a processing environment, the processing system comprising:

a time protocol facility for processing messages sent or received by the processing system to facilitate maintaining time synchronization in a coordinated timing network of a processing environment; and

a channel subsystem for transmitting the messages sent by the processing system and receiving the messages received by the processing system on a communication link;

wherein the time protocol facility is coupled to the channel subsystem; and

wherein the processing of the time protocol facility comprises establishing a logical path to another processing system of the coordinated timing network, the establishing comprising;

successfully exchanging, with a time protocol facility of the another processing system, a command-response message pair initiated by the processing system; and

successfully exchanging, with the another processing system'"'"'s time protocol facility, a command-response message pair initiated by the another processing system.

11. The processing system of claim 10, wherein the time protocol facility comprises a programmable logic circuit.

12. The processing system of claim 10, further comprising:

a central processing unit;

memory coupled to the central processing unit; and

program code logic stored in the memory, the program code logic comprising functions of the time protocol facility, wherein the program code logic is executable by the central processing unit.

13. The processing system of claim 10, further comprising a timing facility that is coupled to the time protocol facility, the timing facility maintaining a local reference clock.

14. A method of establishing a logical path between two processing systems in a coordinated timing network of a processing environment, the method comprising:

transmitting, by a processing system to an attached processing system, a request to establish a logical path between the processing system and the attached processing system, the logical path facilitating time synchronization of the processing system and the attached processing system;

receiving, by the processing system, a response from the attached processing system indicating whether the attached processing system accepted the request transmitted by the processing system;

receiving, by the processing system, another request transmitted by the attached processing system, the another request requesting to establish the logical path between the processing system and the attached processing system;

transmitting, by the processing system to the attached processing system, another response indicating whether the processing system accepted the another request transmitted by the attached processing system; and

establishing the logical path between the processing system and the attached processing system if the response indicates that the request was accepted by the attached processing system and if the another response indicates that the another request was accepted by the processing system.

15. The method of claim 14, further comprising:

detecting whether a data communication link has been reconfigured since the logical path was established on the data communication link; and

initiating the transmitting, by a processing system to an attached processing system, of the request to re-establish the logical path if the data communication link has been reconfigured.

16. The method of claim 14, further comprising:

determining whether the attached processing system has failed to respond to a command to exchange time parameters with the processing system within a pre-determined period of time; and

initiating the transmitting, by the processing system to the attached processing system, of the request to establish the logical path if the attached processing system has failed to respond to the command to exchange time parameters.

17. The method of claim 14, further comprising:

comparing a coordinated timing network (CTN) identification (ID) parameter value of the processing system and a CTN ID parameter value of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the CTN ID parameter value of the processing system differs from the CTN ID parameter value of the attached processing system.

18. The method of claim 14, further comprising:

comparing a system identification parameter value of the processing system and a system identification parameter value of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the system identification parameter value of the processing system is identical to the system identification parameter value of the attached processing system.

19. The method of claim 14, further comprising:

comparing a version number parameter value of a time protocol facility of the processing system and a version number parameter value of a time protocol facility of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the comparing indicates that the processing system'"'"'s time protocol facility is not compatible with the attached processing system'"'"'s time protocol facility.

20. The method of claim 14, further comprising:

comparing a configuration block of a time protocol facility of the processing system and a configuration block of a time protocol facility of the attached processing system; and

refusing to accept the another request transmitted by the attached processing system to establish the logical path if the comparing indicates that the processing system'"'"'s time protocol facility is not compatible with the attached processing system'"'"'s time protocol facility.