Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

From: Jeff Squyres \(jsquyres\) (jsquyres_at_[hidden])
Date: 2006-04-20 10:39:32

Greetings. Apologies it's taken us so long to reply -- we're all at an
Open MPI workshop this week and it's consuming just about all of our

Right now, there is no way to restrict the port range that Open MPI will
use. We simply ask the operating system for available ports and it
gives us a random one that is not being used.

So if you're setting up servers that used fixed TCP/UDP ports, there
shouldn't be a problem -- when MPI jobs run, those servers should be
occupying the TCP/UDP ports in question, and therefore the MPI jobs
won't use them. If you've got dynamic applications that aren't "always
running" (or nearly so) and therefore the TCP/UDP ports in question may
not always be reserved, you *could* clash with MPI jobs (e.g., an MPI
job could randomly take the port that you're expecting to be able to

BTW, I'm *assuming* that your jobs will use non-privileged ports. Is
this right? If they use privileged ports, then there's no conflict --
Open MPI doesn't use privileged ports.

However, in practice, there's little chance of a conflict. The port
range is so large that it's unlikely to happen (of course, saying that
pretty much guarantees that it *will* happen ;-) ). Right now, there's
no way in Open MPI to restrict which TCP ports it uses. If this becomes
a problem for you (i.e., the random MPI-chose-the-same-port-as-your-app
events happen a lot), let us know and we can probably put in some
controls to work around this.

> -----Original Message-----
> From: users-bounces_at_[hidden]
> [mailto:users-bounces_at_[hidden]] On Behalf Of
> Laurent.POREZ_at_[hidden]
> Sent: Tuesday, April 18, 2006 10:09 AM
> To: users_at_[hidden]
> Subject: [OMPI users] Open-MPI and TCP port range
> Hi,
> I am a new user of Open-MPI, and I need to use 2 kinds of
> programs on an unique cluster :
> 1) MPI based programs
> 2) Others, using TCP and UDP
> In order to get my non-MPI programs run, I need to know which
> ports may be used by MPI programs.
> Is there a way to know/set the range of the ports used by MPI
> programs ?
> Thanks
> Laurent.
> _______________________________________________
> users mailing list
> users_at_[hidden]