Yes. It is not unusual to have multiple network interfaces on each host of a cluster. Usually there is a preference to use only one network interface on each host due to higher speed or throughput, or other considerations. It would be useful to be able to explicitly specify the interface to use for cases in which the MPI code does not select the preferred interface.
Charles Doland charles.dol...@ansys.com<mailto:charles.dol...@ansys.com> (408) 627-6621 [x6621] ________________________________ From: users <users-boun...@lists.open-mpi.org> on behalf of John Hearns via users <users@lists.open-mpi.org> Sent: Tuesday, September 1, 2020 12:22 PM To: Open MPI Users <users@lists.open-mpi.org> Cc: John Hearns <hear...@gmail.com> Subject: Re: [OMPI users] Limiting IP addresses used by OpenMPI [External Sender] Charles, I recall using the I_MPI_NETMASK to choose which interface for MPI to use. I guess you are asking the same question for OpenMPI? On Tue, 1 Sep 2020 at 17:03, Charles Doland via users <users@lists.open-mpi.org<mailto:users@lists.open-mpi.org>> wrote: Is there a way to limit the IP addresses or network interfaces used for communication by OpenMPI? I am looking for something similar to the I_MPI_TCP_NETMASK or I_MPI_NETMASK environment variables for Intel MPI. The OpenMPI documentation mentions the btl_tcp_if_include and btl_tcp_if_exclude MCA options. These do not appear to be present, at least in OpenMPI v3.1.2. Is there another way to do this? Or are these options supported in a different version? Charles Doland charles.dol...@ansys.com<mailto:charles.dol...@ansys.com> (408) 627-6621 [x6621]
