EP Multiplexing Support (EPMPX) is an extension to NAS that allows multiple ITI calls, independent of network origin, to be multiplexed over one or more EP subchannels. Host software modifications are required in order to use the EPMPX facility. For many installations this is considerably easier than a migration to NCP and VTAM. The EPMPX approach permits an installation to maintain complete control of its network, increase network throughput and reduce the number of EP subchannels required for its device population.
Virtual circuits (VC's) are managed across EPMPX subchannels in much the same way as logical channels (LC's) are managed across X25 access links. Data that passes between the host and the CCU is enveloped in BSC 3270 frames. Standard BSC 3270 channel programming techniques are used to send and receive packets across an EPMPX subchannel. The VCN is mapped to a BSC 3270 control unit and device address pair for host access method compatibility.
This is a very specialized product. Major changes are required in the Host Access Method/Application for this product. Please contact Comm-Pro for detailed information on NAS EPMPX support. AMDAHL Corporation provides host access to AT&T's BX25 network via their UTS operating system using the Comm-Pro EPMPX interface software. MVS or VM/CMS is required to generate and load a TYPGEN=EP/PEP load module for an IBM 3720, 3725 and 3745 or AMDAHL 4725 or 4745 CCU. AMDAHL provides the necessary UTS utilities to generate and load a TYPGEN=EP 3705 or 4705 load module. Please contact your local AMDAHL representative for detailed information.