User guide

IB0054607-01 A 5-1
5 Configuration of IPoIB
Name Mapping
The FastFabric tools support the concept of a management network and an IPoIB
network. For some clusters the management network will be a low speed network
such as 10/100 Ethernet. For other clusters IPoIB may serve double duty as the
host management network.
The various FastFabric tools will translate from host names provided to and from
IPoIB names as needed. This permits the host names given to be either
management network or IPoIB network names. The default configuration file
assumes that IPoIB host names are formed by adding a -ib suffix to the
management network name. If a different suffix is desired, FF_IPOIB_SUFFIX
can be changed. If IPoIB is also being used as the management network,
FF_IPOIB_SUFFIX can be set to an empty string "".
The translation is driven by the following functions within fastfabric.conf:
ff_host_basename - given a management network or IPoIB hostname,
translate to management network name, should match hostname -s
ff_host_basename_to_ipoib - given a management network name, translate
to IPoIB hostname
More complex mappings can be specified by implementing alternate algorithms
for these functions.
NOTE:
When using IPoIB as the management network, the initial installation of
InfiniBand software cannot be done using FastFabric.
NOTE:
When managing a cluster where the IPoIB settings on the compute nodes
are incompatible with the InfiniBand Management node (for example when a
4K MTU is used on the compute nodes and a 2K MTU is used on the
InfiniBand Management Nodes), it is recommended not to run IPoIB on the
InfiniBand management nodes.