Configuring Performance Buffers; Buffer Pools - Cisco MDS 9000 Series Configuration Manual

Chapter 4 Configuring Interface Buffers
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
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.

Configuring Performance Buffers

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.

Buffer Pools

In the architecture of Generation 2 and Generation 3 modules, receive buffers shared by a set of ports
are called buffer groups. The receive buffer groups are organized into global and local buffer pools.
The receive buffers allocated from the global buffer pool to be shared by a port group are called a global
recieve buffer pool. Global receive buffer pools include the following buffer groups:
•
•
•
•
The 48-port and 24-port 8-Gbps modules have dual global buffer pools. Each buffer pool in the 48-port
Note
modules support 24 ports and in the 24-port modules each buffer pool supports 12 ports.
OL-19445-02, Cisco MDS NX-OS Release 4.2(x)
Reserved internal buffers
Allocated BB_credit buffers for each Fibre Channel interface (user configured or assigned by
default)
Common unallocated buffer pool for BB_credits, if any, to be used for additional BB_credits as
needed
Performance buffers (only used on 12-port 4-Gbps and 4-port 10-Gbps switching modules)
Purpose
Enters configuration mode.
Selects a Fibre Channel interface and enters interface
configuration submode.
Assigns a performance buffer of 45 to the selected
interface. The value ranges from 1 to 145.
Reverts to the factory default of using the built-in
algorithm.
Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
Buffer Pools
4-3