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Subject: Re: [OMPI devel] Enabling debugging and profiling in openMPI (make"CFLAGS=-pg -g")
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2009-06-16 18:04:37

On Jun 12, 2009, at 3:56 PM, Ralph Castain wrote:

> The firewall should already be solved. Basically, you have to define
> a set of ports in your firewall that will let TCP messages pass
> through, and then tell OMPI to use those ports for both the TCP BTL
> and the OOB.
> "ompi_info --params btl tcp" - will tell you the right param to set
> for the TCP BTL
> "ompi_info --params oob tcp" will do the same for the OOB
> Of course, that -does- leave a hole in your firewall that any TCP
> message can exploit. :-/ You could look at more secure alternative
> ways.
> I'm not sure how to solve the NAT problem as it boils down to how to
> specify the names/IP addresses of the nodes behind the NAT. Someone
> who understands NATs better can help you there - I know there is a
> way to do it, but I've never played with it.

This sounds suspiciously like you want to route MPI messages (rather
than just send them peer-to-peer). Be warned that that's somewhat of
a non-trivial exercise...

Alternatively, if you can make outbound connections from behind your
NAT to in front of your NAT, that may work. You'll need to twonk
around in ompi/mca/btl/tcp/ to make that happen. There are likely
ORTE implications as well -- twonking around in ore/mca/oob/tcp/. But
there may be deeper implications than just the connection scheme --
how will you launch the MPI processes, for example?

If you have multiple processes behind multiple different NATs, the
connection scheme will become more complicated -- rendezvous, etc.

Jeff Squyres
Cisco Systems