Configuring Generation 2 Switches and Modules
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
For an example of the configuration of the this example, see
Channel Switching Module Example" section on page
24-port 4-Gbps Fibre Channel Module BB_Credit Buffers
BB_Credit Buffer Allocation Type
User configurable BB_credit buffers
1. ISL = E port or TE port.
The following considerations apply to BB_credit buffers on 24-port 4-Gbps Fibre Channel switching
Each port group on the 24-port 4-Gbps Fibre Channel switching module consists of six ports. The ports
in shared rate mode have bandwidth oversubscription of 2:1 by default. However, some configurations
of the shared ports in a port group can have maximum bandwidth oversubscription of 4:1 (considering
that each port group has 12.8-Gbps bandwidth). The following example configurations are supported by
the 24-port 4-Gbps Fibre Channel switching modules:
OL-16184-01, Cisco MDS SAN-OS Release 3.x
Example Speed and Rate Configuration on a 48-Port 4-Gbps Switching Module
lists the BB_credit buffer allocation for 24-port 4-Gbps Fibre Channel switching modules.
24 Port 4-Gbps Switching Module BB_Credit Buffer Allocation Defaults
BB_credit buffers for ISL connections can be configured from a minimum of 2 buffers to a
maximum of 250 buffers for dedicated rate mode or 16 buffers for shared rate mode.
BB_credit buffers for Fx port mode connections can be configured. The minimum is 2 buffers and
the maximum of 250 buffers for dedicated rate mode or 16 buffers for shared rate mode.
Performance buffers are not supported on this module.
Six ports with shared rate mode and 4-Gbps speed (2:1 oversubscription) (default)
Cisco MDS 9000 Family CLI Configuration Guide
Buffer Credit Allocation
"Configuring a 48-port 4-Gbps Fibre
BB_Credit Buffers Per Port Defaults
Dedicated Rate Mode
Shared Rate Mode