IBM Network Control Program

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This article is about the IBM Network Control Program software. For the ARPANET Network Control Program, see Network Control Program.

The IBM Network Control Program (NCP) ran on an IBM 3704, 3705 or 3745. It caused the machine to become a Systems Network Architecture Physical Unit Type 4 (PU4). A PU4 usually had SDLC links to remote cluster controllers (PU1/PU2) and optional SDLC links to other PU4s. Polling and addressing of the cluster controllers was performed by the NCP without mainframe intervention.

A local NCP connected to a System/370 channel via single address. A remote NCP had no direct connection to a mainframe. Instead a connection was made through a local NCP via SNA packet switching. NCP provided the link control and Network layer functions of a Wide area network. More information about NCP can be found in the article by W. S. Hobgood.

[edit] Further reading

• W. S. Hobgood. "The role of the Network Control Program in Systems Network Architecture". Vol 15, No 1. IBM Systems Journal. Retrieved on 2006-08-26.