Companies continue to rely on older applications residing on mainframes. Initially, access to these applications was through SNA. Today, newer applications are generally based on TCP/IP. Initially, companies supported both these networks separately, but are now seeking ways to consolidate their SNA traffic onto the TCP/IP network. However, it is not economically practical to convert existing SNA applications to TCP/IP and, in many cases, conversion might even be technically impractical because of the lack of source code, adequate skills, or both.

With Enterprise Extender (EE), you can extend the reach of SNA applications and data to include TCP/IP networks and IP-attached clients with levels of reliability, scalability, and control similar to those that SNA users have used. EE integration uses standard IP technology and does not require new hardware or new software in the IP backbone.

You can use an IP network for SNA sessions with Enterprise Extender, which provides enablement of IP applications and convergence on a single network transport while preserving SNA application and endpoint investment. An EE connection is a logical connection that represents IP connectivity from a host to a specified IP address or host name. Conceptually, an IP network looks like an APPN/HPR transmission group (TG) in a session route.

In summary, EE is an extension of High Performance Routing (HPR) technology that provides encapsulation of SNA application traffic within UDP frames by HPR-capable devices at the edges of an IP network. To the IP network, the SNA traffic is UDP datagrams that get routed without hardware or software changes to the IP backbone. To the user, the session is normal SNA with predictable performance and high availability. By wrapping the SNA application in this way, EE enables SNA data to be carried over an IP backbone without changing either the SNA applications or the IP hardware.

For more information about Enterprise Extender, see Migrating Subarea Networks to an IP Infrastructure, SG24-5957-00 (a member of the IBM® Redbooks® library) http://www.redbooks.ibm.com.