MSC and IMS-to-IMS TCP/IP communications

For MSC, the TCP/IP connections between two IMS Connect instances complete a path for an MSC physical link. One or more MSC logical links can be assigned to the MSC physical link.

Messages on MSC links travel in both directions. For each MSC logical link, two socket connections are opened: a send socket and a receive socket. To support MSC links, you must define a pair of corresponding TCP/IP connections, one in each IMS Connect instance on each side of the IMS-to-IMS TCP/IP connection.

To define a complete IMS-to-IMS TCP/IP communications path for MSC, you must code the following items in the IMS Connect and IMS instances at each side of the connection:

• In IMS Connect, the IMS Connect configuration statements, including the RMTIMSCON statement, which is required for IMS-to-IMS TCP/IP communications, and the MSC statement, which is required for communication between IMS Connect and MSC.
• In IMS, the MSC system definition macros or type-2 CREATE commands that are required to define all MSC link types. The MSPLINK macro and the CREATE MSPLINK command have parameters that are specific to the TCP/IP MSC physical link type.

A simplified IMSplex configuration is required to support IMS-to-IMS TCP/IP communications for MSC. The communications path between IMS Connect and MSC is managed by the Structured Call Interface (SCI) component of the IMSplex. IMS type-2 command support for IMS Connect and MSC also requires the Operations Manager (OM) component of the IMSplex.

For MSC links that use TCP/IP generic resources, IMS Connect provides routing and affinity management support.

Security for the TCP/IP connection can be implemented by using the optional RACF® PassTicket support. Transaction authorization can also be implemented in the IMS system.

In each IMS system, a TCP/IP MSC link is operationally like a VTAM® MSC link. An MSC physical link can be started by issuing either the IMS type-1 command /RSTART LINK or the IMS type-2 command UPDATE MSLINK START(COMM) in either one of the linked IMS systems.

In IMS Connect, after a link has been started, you can monitor, stop, and restart the MSC links and their associated socket connections by using IMS Connect WTOR, z/OS® MODIFY, or IMS type-2 commands. In IMS, most definition, operations, and administrative tasks and processes are the same for the MSC TCP/IP link type as they are for the MSC VTAM link type.