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Subject: Re: [OMPI users] How are IP addresses determined?
From: Ashley Pittman (ashley_at_[hidden])
Date: 2011-02-17 05:21:10


On 17 Feb 2011, at 04:56, Barnet Wagman wrote:

> I've run into a problem involving accessing a remote host via a router and I think need to understand how opmpi determines ip addresses. If there's anything posted on this subject, please point me to it.
>
> Here's the problem:
>
> I've installed opmpi (1.4.3) on a remote system (an Amazon ec2 instance). If the local system I'm working on has a static ip address (and a direct connection to the internet), there's no problem. But if the local system accesses the internet through a router (which itself gets it's ip via dhcp), a call to runmpi command hangs.

I would strongly recommend that all machines involved in a Open MPI job are at the same geographical location. This includes all nodes doing computation but also the "submission host". For EC2 this would mean all in the same region.

As you correctly notice not only are your hosts are on the same network which means that they won't all be able to contact each other over the network, without this OpenMPI is not going to be able to work.

Ashley.

-- 
Ashley Pittman, Bath, UK.
Padb - A parallel job inspection tool for cluster computing
http://padb.pittman.org.uk