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

3–Fabric Manager Configuration
Configuring the QLogic Fabric Manager
Fabric Programming
SwitchLifetime, HoqLife, and VLStallCount can be used to relieve fabric
congestion and avoid fabric deadlocks by discarding packets. Discards help
prevent back pressure from propagating deep into the core of the fabric, however
such discards will cause end nodes to need to timeout and retransmit.
If a packet stays at the Head of a Switch Egress Port for more than HoqLife, it is
discarded. Similarly a packet queued in a switch for more than SwitchLifetime is
discarded.
Specified as integer time using ns, us, ms, s, m, or h as units. SwitchLifetime and
HoqLife can also be set to infinite. VLStallCount controls a second tier more
aggressive discard. If VlStallCount packets in a row are discarded due to HoqLife
by a given VL on an egress port. That egress port's VL enters the VL Stalled State
and discards all that VL's egress packets for 8*HoqLife. Packets discarded for any
of these reasons will be included in the TxDiscards counter which is queryable via
FastFabric.
The parameters in Table 3-10 control Fabric Configuration and Programming.
Table 3-10. Sm Fabric Configuration Parameters
Parameter
Default
Value
Description
SmKey 0 64-bit key of SM, redundant SMs must have
same key
MKey 0 64-bit mkey to secure SMA ports this SM
manages
SwitchLifetime 33ms A packet queued in a switch for more than
SwitchLifetime is discarded. Specified
as integer time using ns, us, ms, s, m, or h
as units. Can also be set to infinite
HoqLife 8ms If a packet stays at the Head of a Switch
Egress Port for more than HoqLife, it is discarded.
Specified as integer time using ns,
us, ms, s, m, or h as units. Can also be set
to infinite
VlStallCount 7 Controls a second tier more aggressive discard.
If VlStallCount packets in a row
are discarded due to HoqLife by a given VL
on an egress port. That egress port's VL
enters the VL Stalled State and discards all
that VL's egress packets for 8*HoqLife.
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