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

2–Advanced Fabric Manager Capabilities
Fabric Unicast Routing
impacts of starting or completing multiple applications which are running on
the same fabric.
3. For Fat Tree topologies, an additional level of adaptive routing can be
enabled (Tier1FatTree) which permits even more flexible adaptive
routing and can better balance traffic among multiple core switches.
The configuration allows adaptive routing to be enabled for lost routes and
congestion, for lost routes only, and optionally support adaptive routing across
multiple switches in Fat Tree topologies (both FBB or oversubscribed fat trees).
The lost route parameter provides alternative routes to the switch firmware. When
routes are lost, the switch firmware has immediate access to an alternate route
instead of waiting for the Fabric Manager to reprogram the switch tables. If this
parameter is not set, the alternate routes are also used to redirect traffic during
periods of congestion.
For pure fat trees topologies, the switch has more options for traffic redirection. If
the Tier1FatTree parameter is enabled, tier1 routing is also enabled. When
Tier1FatTree parameter is enabled, it enables adaptive routing across different
spines. When Tier1FatTree parameter is disabled, adoption only occurs
among ISLs connected between pairs of switches. Tier1FatTree parameter is
ignored when DOR/UpDown routing is selected for Mesh/Torus.
The following is the adaptive routing section of the qlogic_fm.xml-sample file:
0
0
0
LMC, Dispersive Routing and Fabric Resiliency
The SM also supports LID Mask Control (LMC). LMC allows for more than 1 LID
to be assigned to each end node port in the fabric, specifically 2 LMC LIDs will be
assigned. This allows the SM to configure the fabric with multiple routes between
each end node port, allowing applications to load balance traffic (for example,
using algorithms such as PSM's dispersive routing) across multiple routes or
provide rapid failover using techniques like Alternate Path Migration (APM).
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