Migrating NCP connections to APPN connections results in the creation of additional NCP control blocks, which can require additional storage space and cycles in the NCP. In addition, when a node or link along a route fails, sessions using that route fail.

Using the High-Performance Routing (HPR), you can migrate NCP connections to APPN connections without incurring the associated increase in storage and cycles. HPR uses a rapid transport protocol (RTP) connection to transport session traffic between session endpoints. HPR routes can also traverse an existing subarea network, as HPR support provides for the mapping of HPR routes over VR-based TGs.

In addition, if a node or link on an HPR route fails and an alternate HPR route exists between HPR session endpoints, HPR automatically switches routes and sessions are not disrupted. A method is also available that the operator can use to force an HPR path switch.

To use HPR over an NCP you must have, at minimum, NCP Version 7 Release 3 (and 37xx controllers supported by NCP Version 7 Release 3). To use HPR over a subnetwork boundary where one or both of the border nodes are composite network nodes, you must have, at minimum, NCP Version 7 Release 5.