APPN/HPR

Advanced Peer to Peer Networking / High Performance Routing (APPN/HPR) is an advanced SNA technique developed by IBM that enables SNA LU-LU sessions between peer devices using dynamic routing. This is in contrast to the more traditional, strictly hierarchical, subarea-oriented SNA.

APPN/HPR comprises two components: RTP (Rapid Transport Protocol) and ANR (Automatic Network Routing); ANR provides the routing, while RTP handles the route control and recovery and is responsible for the non-destructive routing around failures.

APPN/HPR links can be established over different transport mechanisms, of which Enterprise Extender (EE) is only one; therefore, EE always involves APPN/HPR.

EE carries APPN/HPR over an IP backbone, in NLPs (Network Layer Packets), allowing APPN to see the IP network as a single hop connection. UDP is the chosen protocol because it provides the best performance. One logical APPN/HPR link can traverse many hops, some of which may be EE. A system's whole EE environment may be just a small part of a much bigger picture.

Many of the most useful EE diagnostic tasks are performed at the non-EE level, that is, APPN/HPR level.