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Fibre Channel Interfaces
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m .
Performance Buffers
Regardless of the configured receive BB_credit value, additional buffers, called performance buffers,
improve switch port performance. Instead of relying on the built-in switch algorithm, you can manually
configure the performance buffer value for specific applications (for example, forwarding frames over
FCIP interfaces).
For each physical Fibre Channel interface in any switch in the Cisco MDS 9000 Family, you can specify
the amount of performance buffers allocated in addition to the configured receive BB_credit value.
The default performance buffer value is 0. If you use the default option, the built-in algorithm is used.
If you do not specify this command, the default option is automatically used.
To configure performance buffers for a Fibre Channel interface, follow these steps:
Command
Step 1
switch# config t
Step 2
switch(config)# interface fc1/1
switch(config-if)#
Step 3
switch(config-if)# switchport
fcrxbbcredit performance-buffers 45
switch(config-if)# switchport
fcrxbbcredit performance-buffers default
Use the show interface bbcredit command to display performance buffer values and other BB_credit
Note
information.
Extended BB_credits
The BB_credits feature allows you to configure up to 255 receive buffers. This number is insufficient for
long haul links. To facilitate BB_credits for long haul links, you can use the extended BB_credits flow
control mechanism. This feature allows you to configure up to 3,500 receive BB_credits on a Fibre
Channel port.
Cisco MDS 9000 Family Configuration Guide
11-14
Chapter 11
Purpose
Enters configuration mode.
Configures the specified interface.
Assigns a performance buffer of 45 to the selected
interface. The value ranges from 1 and 145.
Reverts to the factory default of using the built-in
algorithm.
OL-6973-03, Cisco MDS SAN-OS Release 2.x
Configuring Interfaces
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