Fabric Manager Users Guide, Version 6.1, Revision A - QLogic

2–Advanced Fabric Manager Capabilities
Mesh/Torus Topology Support
To permit this, the QLogic Fabric Manager allows LMC>1 to be configured for
Mesh/Torus fabrics. In which case one LID is used for the Up/Down route and all
the remaining routes are used for DOR routes. So for example an LMC of two will
cause four LIDs per Channel Adapter. One will be for Up/Down and the remaining
three will be for optimized DOR routes. When the SM is queried for a PathRecord
it will report only the three DOR LIDs for non-disrupted paths and only the one
Up/Down LID for disrupted paths.
All alternate DOR routes will be optimized per the LMC and fabric resiliency
section above.
NOTE:
In order to take advantage of multi-path routing in a mesh/torus, there must
be more than one ISL between switches per dimension. In order to avoid
credit loops, all multi-path routes configured by the QLogic Fabric Manager
will obey the DOR routing rules. Use of distinct switch chassis is not
available for DOR alternate routes.
Switch and Host Channel Adapter VLs
When operating a Mesh/Torus fabric, more than one VL is always required. Many
devices ship by default with only one VL enabled. Prior to running with the
dor-updown algorithm, the switches and Host Channel Adapters must first be
configured for the proper number of VLs and the appropriate MTU. Refer to
Appendix D for more information on the number of VLs that are needed for
various combinations.
Bootstraping the fabric
For fabrics with QLogic Externally Managed switches, it will be necessary to have
the SM operational in order to configure the switches. Also other verification
operations, such as topology verification may be needed prior to putting the fabric
into normal operation.
Due to the stricter topology and VL requirements of the Fabric Manager for
Mesh/Torus fabrics, it can be helpful to pre-configure and verify this information
prior to enabling the dor-updown routing algorithm in the Fabric Manager.
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