OMPI always tries to use the lowest numbered address first - just a natural ordering. You need to tell it to use just the public ones for this topology. Use the oob_tcp and btl_tcp parameters to do this. See "ompi_info --param oob tcp" and "ompi_info --param btl tcp" for the exact syntax.
Sent from my iPad On Oct 4, 2011, at 10:21 AM, "(.-=Kiwi=-.)" <heffe...@gmail.com> wrote: > We are constructing a set of computers with Open MPI and there's a small > problem with mixing public and private IPs. > > We aren't sure about what's causing the problem or how to solve it. > > The files are shared thanks to NFS and we have a couple computers with > private IPs and public IPs that we want them to send MPI work to some > machines that have public IPs. > > I'm going to try to describe with example IPs. > > Computer 1 sees itself as eth0: 172...2 but has a public IP assigned: > 210...2 > Computer 2 sees itself as eth0: 172...3 but has a public IP assigned: > 210...3 > Computers outside the subnet directly have public IPs assigned: 210...100+ > > The computers outside see Computer 1 and 2 only with 210... they can't see > the 172... internal IPs. > > If an outside computer launches mpirun to Computer 1, it works ok. > If Computer 1 tries to launch mpirun to Computer 2 (with 172...) it also > works ok (not with 210... because they don't know that that's their public > IP, but that's not an issue). > > The problem comes when Computer 1 or 2 try to launch mpirun to outside > computers. > > We tried to check out what was happening and installed wireshark on an > outside computer and it seems that the ssh part works ok (the ssh talk > between 210...2 and 210...101 is ok), but after that the outside computer > tries to send a TCP SYN package to 172...2 instead of 210...2 and the rest of > the packets onward the same. > > Is there a way to solve this problem? > > I've read this ( > http://www.open-mpi.org/community/lists/users/2009/11/11184.php ) but I'm not > really sure what he's doing there. > > We have the option of plugging Computer 1 and Computer 2 directly to the > switch that the outside computers are on, but we'd rather not because we'd > prefer the computers to stay on the private network, but if there's no other > way, I guess we can. > > Can it be done without having to change the network topology? > > Thanks in advance. > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
