LAPI: A high performance Low-level communications API

	    Rama Govindaraju, IBM Power Parallel Division

			      Abstract

We describe the architecture, implementation and performance of a new
high performance communications API on the RS/6000 SP. We also discuss
the motivation for LAPI, its properties, some implementation details
relating to performance enhancement, and experiences of some customers
currently using LAPI. We also provide a comparison of LAPI with other
communication libraries available on the RS/6000 SP.