Cisco MDS 9000 Series Configuration Manual page 120

Buffer Pools
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
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24-Port 8-Gbps Fibre Channel Module BB_Credit Buffers
Table 4-2
Table 4-2
BB_Credit Buffer Allocation
Default BB_credit buffers
Maximum BB_credit buffers
Total Number of BB_Credit Buffers per Module
Ports 1 through 12
Ports 13 through 24
1. When connected to Generation 1 modules, reduce the maximum BB_credit allocation to 250.
The following guidelines apply to BB_credit buffers on 24-port 8-Gbps Fibre Channel switching
modules:
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Each port group on the 24-port 8-Gbps Fibre Channel switching module consists of three ports. The ports
in shared rate mode in a port group can have a maximum bandwidth oversubscription of 10:1 considering
that each port group has 12.8-Gbps bandwidth.
The following example configurations are supported by the 24-port 8-Gbps Fibre Channel switching
modules:
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Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
4-8
One port with dedicated rate mode and 4-Gbps speed plus
three ports with dedicated rate mode and 2-Gbps speed plus
two ports with shared rate mode and 4-Gbps speed (4:1 oversubscription)
Six ports with dedicated rate mode and 2-Gbps speed
lists the BB_credit buffer allocation for the 24-port 8-Gbps Fibre Channel switching module.
24-Port 8-Gbps Switching Module BB_Credit Buffer Allocation
BB_credit buffers allocated for ports 1 through 12 and 13 through 24 can be a maximum of 6000
each so that the load is distributed.
BB_credit buffers for ISL connections can be configured from a minimum of 2 buffers to a
maximum of 500 buffers for dedicated rate mode.
BB_credit buffers for Fx port mode connections can be configured. The minimum is 2 buffers and
the maximum of 500 buffers for dedicated rate mode or 32 buffers for shared rate mode.
Performance buffers are not supported on this module.
Three ports with shared rate mode and 8-Gbps speed (2:1 oversubscription) (default)
One port with dedicated rate mode and 8-Gbps speed plus
two ports with shared rate mode and 8-Gbps speed (4:1 oversubscription)
One port with dedicated rate mode and 8-Gbps speed plus
one port with dedicated rate mode and 4-Gbps speed plus
one port with shared rate mode and 8-Gbps speed (10:1 oversubscription)
Two ports with dedicated rate mode and 4-Gbps speed plus
one port with shared rate mode and 8-Gbps speed (2:1 oversubscription)
Chapter 4 Configuring Interface Buffers
BB_Credit Buffers Per Port
Dedicated Rate Mode Shared Rate Mode
8-Gbps Speed 8-Gbps Speed
ISL Fx Port Fx Port
500 32 32
1 1
500 500 32
6000
6000
OL-19445-02, Cisco MDS NX-OS Release 4.2(x)