Historical: Running on Seaborg
Seaborg Decommissioned January 2008

Communication protocols

There are two separate implementations of the communications library on the SP:

Internet Protocol (IP)

This implementation uses the standard IP protocol that commonly links computers over ethernet networks.

User Space (US) Communication Subsystem

This communication subsystem is designed to take advantage of the SP's high performance switch.

You will use the "US" protocol in almost all cases. The library is dynamically linked to your code at runtime. You do not have to modify your source code, but you must specify a protocol when you run your program.

A number of environment variables are set for you by default so you will automatically run using the high speed communications switch. These environment variable settings are:

	MP_ADAPTER_USE=dedicated
	MP_EUIDEVICE=csss
	MP_EUILIB=us

For LoadLeveler scripts, specify the protocol with this line:

#@network.MPI = csss,not_shared,us