XRF, MSC, and TCP/IP generic resources

When an XRF pair of active and alternate IMS systems use TCP/IP generic resources to support MSC, the MSC physical link and all of its parallel sessions have affinity to the active IMS system.

To support TCP/IP generic resources, the same GENIMSID parameter must be specified in the DFSDCxxx PROCLIB member of both the active and alternate IMS systems in the XRF pair.

When a takeover occurs, IMS switches the affinity of the logical links from the active IMS system to the alternate IMS system, which becomes the new active IMS system.

IMS also notifies IMS connect of the failure of the active IMS system within the IMSplex. IMS Connect terminates the sockets that were active at the time of the failure and releases the affinity between the MSC physical link and the failed IMS system.

To verify that the affinity to the failed IMS system has been released, issue an IMS Connect command to display the status of the physical link. If IMS Connect has not released the affinity status, such as might happen if IMS Connect was not notified of the takeover, clean up the sockets by stopping and restarting the MSC link by issuing the appropriate IMS Connect commands.

After the affinity status is deleted in IMS Connect, you can start the MSC links on the new active IMS system. After the link is started in the new active IMS system, the link will have affinity with the new active IMS system and IMS Connect will show the new affinity status.

An XRF alternate IMS system will not respond to a restart request from a remote IMS system outside of the IMSplex. MSC links cannot be started on an alternate IMS system until the takeover completes and the alternate IMS system becomes the new active IMS system.