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Subject: Re: [OMPI users] Problem with sending messages from one of the machines
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2010-11-11 14:12:46

On Nov 11, 2010, at 2:04 PM, Krzysztof Zarzycki wrote:

> I'm working with Grzegorz on the mentioned problem.
> If I'm correct on checking the firewall settings, "iptables --list" shows an empty list of rules.
> The second host does not have iptables installed at all.
> So what can be a next reason of this problem?

How many network interfaces do you have on these nodes? Aside from loopback, are all network interfaces reachable from all others? (that isn't an absolute requirement, but it's easy to talk about if they're all reachable from all others)

> By the way, how can I enforce mpirun to use specific ethernet interface for connections, if I have several possible?

Use the btl_if_include MCA parameter. For example:

  mpirun --mca btl_if_include eth1,eth2 -np 8 --hostfile foo my_mpi_program

Hopefully eth1 and eth2 are the same on both hosts (i.e., eth1 on hostA is reachable by eth1 on hostB; ditto for eth2).

See the FAQ for more details on other ways of setting MCA parameters (environment vars, files, etc.).

Jeff Squyres
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