Cisco MDS 9000 Series Configuration Manual page 119

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
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When you configure port mode to auto or E for all ports in the global buffer pool, you need to reconfigure
buffer credits on one or more of the ports. The total number of buffer credits configured for all the ports
in the global buffer pool should be reduced by 64.
48-Port 8-Gbps Fibre Channel Module BB_Credit Buffers
Table 4-1
Table 4-1
BB_Credit Buffer Allocation
Default BB_credit buffers
Maximum BB_credit buffers
Total Number of BB_Credit Buffers per Module
Ports 1 through 24
Ports 25 through 48
The following guidelines apply to BB_credit buffers on 48-port 8-Gbps Fibre Channel switching
modules:
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Each port group on the 48-port 8-Gbps Fibre Channel switching module consists of six 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 48-port 8-Gbps Fibre Channel switching
modules:
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OL-19445-02, Cisco MDS NX-OS Release 4.2(x)
Port Mode: auto or E for the first half of the ports, the second half of the ports or for all of the ports
Rate Mode: dedicated
Buffer Credits: default value
lists the BB_credit buffer allocation for the 48-port 8-Gbps Fibre Channel switching module.
48-Port 8-Gbps Switching Module BB_Credit Buffer Allocation
BB_credit buffers allocated for ports 1 through 24 and 25 through 48 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.
Six ports with shared rate mode and 8-Gbps speed (4:1 oversubscription) (default)
One port with dedicated rate mode and 8-Gbps speed plus
five ports with shared rate mode and 8-Gbps speed (10:1 oversubscription)
Two ports with dedicated rate mode and 4-Gbps speed plus
four ports with shared rate mode and 4-Gbps speed (4:1 oversubscription)
BB_Credit Buffers Per Port
Dedicated Rate Mode
8-Gbps Speed
ISL Fx Port
250 32
500 500
6000
6000
Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
Buffer Pools
Shared Rate Mode
8-Gbps Speed
Fx Port
32
32
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