Message routing when an IMSplex and MSC network coexist

When an IMSplex with shared queues and an MSC network coexist, IMS routes messages between front-end, back-end, and remote IMS systems using origin and destination names, MSC SYSIDs, and IMSIDs.

IMS uses the coupling facility and the shared queues to route messages within the IMSplex. IMS uses MSC links only to route messages to IMS systems outside of the IMSplex. Any MSC link definitions that exist between IMS systems in the IMSplex are not used.

Transactions defined for routing in an MSC network can also be routed in an IMSplex with shared queues but the method used for routing is that of the IMSplex and not MSC; however, the IMSplex does recognize the MSC SYSID attributes of the transaction. The recognition of the SYSIDs by the IMSplex allows the IMSplex to handle remote transaction in a manner similar to the MSC network. This also has implications for local processing affinity.

Transactions not specifically defined for routing in an MSC network cannot be routed outside of the IMSplex using an MSC link.