# 4.8.3. Networking support / options

The following are command line options for various network types that can be used with `configure`:

- `--with-fca=DIR`: Specify the directory where the Mellanox FCA library and header files are located.

  FCA is the support library for Mellanox switches and HCAs.

- `--with-hcoll=DIR`: Specify the directory where the Mellanox hcoll library and header files are located. This option is generally only necessary if the hcoll headers and libraries are not in default compiler/linker search paths.

  hcoll is the support library for MPI collective operation offload on Mellanox ConnectX-3 HCAs (and later).

- `--with-knem=DIR`: Specify the directory where the knem libraries and header files are located. This option is generally only necessary if the knem headers and libraries are not in default compiler/linker search paths.

  knem is a Linux kernel module that allows direct process-to-process memory copies (optionally using hardware offload), potentially increasing bandwidth for large messages sent between messages on the same server. See the Knem web site for details.

- `--with-libfabric=DIR`: Specify the directory where the OpenFabrics Interfaces `libfabric` library and header files are located. This option is generally only necessary if the libfabric headers and libraries are not in default compiler/linker search paths.

  Libfabric is the support library for OpenFabrics Interfaces-based network adapters, such as Cisco usNIC, Intel True Scale PSM, Cray uGNI, etc.

- `--with-libfabric-libdir=DIR`: Look in directory for the libfabric libraries. By default, Open MPI will look in `DIR/lib` and `DIR/lib64`, which covers most cases. This option is only needed for special configurations.

- `--with-portals4=DIR`: Specify the directory where the Portals4 libraries and header files are located. This option is generally only necessary if the Portals4 headers and libraries are not in default compiler/linker search paths.

  Portals is a low-level network API for high-performance networking on high-performance computing systems developed by Sandia National Laboratories, Intel Corporation, and the University of New Mexico. The Portals 4 Reference Implementation is a complete implementation of Portals 4, with transport over InfiniBand verbs and UDP.

- `--with-portals4-libdir=DIR`: Location of libraries to link with for Portals4 support.

- `--with-portals4-max-md-size=SIZE` and `--with-portals4-max-va-size=SIZE`: Set configuration values for Portals 4

- `--with-psm=<directory>`: Specify the directory where the QLogic InfiniPath / Intel True Scale PSM library and header files are located. This option is generally only necessary if the PSM headers and libraries are not in default compiler/linker search paths.

  PSM is the support library for QLogic InfiniPath and Intel TrueScale network adapters.

- `--with-psm-libdir=DIR`: Look in directory for the PSM libraries. By default, Open MPI will look in `DIR/lib` and `DIR/lib64`, which covers most cases. This option is only needed for special configurations.

- `--with-psm2=DIR`: Specify the directory where the Intel Omni-Path PSM2 library and header files are located. This option is generally only necessary if the PSM2 headers and libraries are not in default compiler/linker search paths.

  PSM is the support library for Intel Omni-Path network adapters.

- `--with-psm2-libdir=DIR`: Look in directory for the PSM2 libraries. By default, Open MPI will look in `DIR/lib` and `DIR/lib64`, which covers most cases. This option is only needed for special configurations.

- `--with-ucx=DIR`: Specify the directory where the UCX libraries and header files are located. This option is generally only necessary if the UCX headers and libraries are not in default compiler/linker search paths.

- `--with-ucx-libdir=DIR`: Look in directory for the UCX libraries. By default, Open MPI will look in `DIR/lib` and `DIR/lib64`, which covers most cases. This option is only needed for special configurations.

- `--with-usnic`: Abort configure if Cisco usNIC support cannot be built.