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Subject: Re: [OMPI devel] Regarding Connection establishment in OpenMPI (Jeff Squyres)
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-09-06 16:57:18

On Sep 6, 2011, at 1:24 PM, Bhargava Ramu Kavati wrote:

> As per our last discussion, MPI_INIT(..) uses TCP socket to exchange its service-id/lid with other MPI processes. I assume this applies irrespective of underlying library used to establish connection i.e libibcm or librdmacm. Please correct me if I am wrong.

It can use librdmacm, but it doesn't have to (and doesn't by default). librdmacm uses its own internal communications -- I'm not sure what transport layer it uses. By default, however, OMPI uses a TCP-based connection mechanism.

Jeff Squyres
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