Brocade Communications Systems Brocade 8/12c Command Reference Manual page 178

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configure
Per-frame Route Priority
Long Distance Fabric
BB Credit
Insistent Domain ID Mode
Disable Default PortName
Edge hold time
Virtual Channel Settings
VC Priority specifies the class of frame traffic given priority for a virtual channel. The switch enables
fine-tuning for a specific application by configuring the parameters for eight virtual channels. The first two
virtual channels are reserved for switch internal functions and are not available for modification.
The default virtual channel settings have already been optimized for switch performance. Changing the
default values can improve switch performance but can also degrade performance. Do not change these
settings without fully understanding the effects of the changes.
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In addition to the eight virtual channels used in frame routing priority, support is
also available for per-frame-based prioritization when this value is set. When
Per-frame Route Priority is set to 1, the virtual channel ID is used in conjunction
with a frame header to form the final virtual channel ID.
When this mode is set to 1, ISLs in a fabric can be up to 100 km long. The exact
distance level is determined by the per-port configuration on the E_Ports of each
ISL. Both E_Ports in an ISL must be configured to run the same long-distance
level; otherwise, the fabric will be segmented.
An Extended Fabrics license is required to set this mode.
The buffer-to-buffer (BB) credit represents the number of buffers available to
attached devices for frame receipt. The range of allowed values varies depending
on other system settings (see Unicast-only Operation). Refer to the Fabric OS
Administrator's Guide for more information on platform-specific BB Credit
limitations.
When this mode is set, the switch attempts to acquire from the fabric the domain
number programmed in its "Switch Fabric Settings." If the operation fails, the
switch will segment from the fabric. There is no longer a need to disable the switch
before configuring this parameter.
When this mode is set, the switch does not generate a default port name.
Configures the maximum time a frame can wait after it is received on the ingress
port and before it is delivered to the egress port. If the frame waits in the egress
buffer for more than the configured hold time, the switch drops the frame,
replenishes sender's credit, and increments the counters sts_tx_timeout and
er_c3_timeout on the TX and RX ports respectively. The frame-timeout indicates a
slow draining or a congestion or bottleneck in the fabric. Decreasing hold time on
the Edge switches may reduce frame drop counts in the core switches. This
parameter is stored persistently in the configuration file. You can configure Edge
hold time only on the default switch. Choose one of the following options:
0
Low edge hold time (80 milliseconds).
1
Medium edge hold time (220 milliseconds).
2
High edge hold time (500 milliseconds). This is the default value.
Fabric OS Command Reference
53-1001764-01