Select your APPC networking protocol

When choosing the advanced program-to-program communications (APPC) networking protocol for your business, you should understand some of the operational characteristics for APPN and HPR. These operational characteristics may affect communication performance on your system.

Note:

While you can run APPC without using APPN or HPR, it may be advantageous to use APPN or HPR since they require less configuration than running pure APPC for your applications.

To help you choose your APPC networking protocol, consider the following:

HPR provides a significant enhancement over APPN in terms of network availability by establishing and maintaining end-to-end connections and the ability to switch paths transparently. For HPR, segmentation and reassembly are accomplished in the central processing unit (CPU). For APPN, the segmentation and reassembly happen in the input/output processor (IOP). This HPR capability of being able to transparently switch paths comes with additional central processing (CPU) usage as compared to APPN.
Enterprise Extender is a networking architecture that allows Systems Network Architecture (SNA) applications to run over Internet Protocol (IP) networks using High Performance Routing (HPR). This is the preferred way to run SNA applications over IP networks with communications input/output adapters (IOAs), such as Gigabit Ethernet, since these IOAs do not require an input/output processor (IOP). Communications adapters that do not use an IOP do not support SNA, therefore, Enterprise Extender is required to run SNA over these adapters. IBM® recommends that Enterprise Extender be used in place of AnyNet®. For more information, see Migration from AnyNet to Enterprise Extender.
The choice of which protocol to use really comes down to deciding whether the high availability features of HPR are desirable in your environment. When determining whether to use APPN or HPR, you should consider the following:
- The high-availability feature of HPR
- The feasibility of higher CPU usage for your environment with HPR
- The requirement to use HPR with Enterprise Extender

You can control the selection of APPN or HPR easily by manipulating the network attributes. It is just as simple to change from HPR to APPN as it is to change from APPN to HPR. The best way to determine the affect of using HPR and APPN in your environment would be to perform some of your own benchmarks.