According to third-party developers, IBM Corp’s strategy for supporting 3270 terminal applications as SNA evolves to a peer-type environment is to use a more robust protocol as the transport mechanism. Computer Systems News says that the intention is to support only 3270 terminal data streams and LU6.2 sessions in Systems Application Architecture, and this ensures that existing terminal-to-host applications will be preserved as APPN permeates SNA systems and programs. Advanced Peer-to-Peer Networking is intended to make SNA more flexible and less mainframe-oriented, and IBM claims that it will help SNA backbones better support local area network traffic, reduce the amount of system administration and provide dynamic routing. However, over 90% of SNA transactions and applications are of the 3270 terminal type that relies on LU2 sessions, and as IBM lays out its APPN strategy, users have become concerned about the future viability of those applications. Commentators say that IBM’s 3270 LU6.2 development – also known as the universal data stream – will encapsulate LU2 and other LU session types, similar to the encapsulation techniques that router vendors use to funnel multiple protocols over Internet Protocol backbones. In the case of the AS/400, 5250 terminal data streams use LU6.2 for terminal communications with AS/400 hosts. There is speculation that IBM will converge the 5250 and 3270 data streams into one and run the single data stream over LU6.2. The method used could be a forerunner to the technique for supporting 3270 applications in APPN. However, others say that running the 3270 data stream over LU6.2 and encapsulating LU2 in LU6.2 are not the same. A 3270 data stream on top of LU6.2 may require a redesigning of application subsystems, while the encapsulation of LU2 is a much easier proposition, and users will not have to rewrite applications.
