> # 4/44-Port 8-Gbps Host-Optimized Fibre Channel Module BB_Credit Buffers

> Table 14-4 lists the BB_credit buffer allocation for the 4/44-port 8-Gbps Fibre Channel switching module.

> Table 14-4 4/44-Port 8-Gbps Switching Module BB_Credit Buffer Allocation
> BB_Credit Buffer Allocation | BB_Credit Buffers Per Port
> --- | ---
> Dedicated Rate Mode 8-Gbps Speed | Shared Rate Mode 8-Gbps Speed
> ISL | Fx Port | Fx Port
> Default BB_credit buffers | 125 | 32 | 32
> Maximum BB_credit buffers | 250 | 250 | 32
> Total number of BB_credit buffers per module | 6000

> The following guidelines apply to BB_credit buffers on 4/44-port 8-Gbps Fibre Channel switching modules:

> - 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 250 buffers for dedicated rate mode or 32 buffers for shared rate mode.
> - Performance buffers are not supported on this module.

> Each port group on the 24-port 8-Gbps Fibre Channel switching module consists of 12 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 4/44-port 8-Gbps Fibre Channel switching modules:

> - Twelve ports with shared rate mode and 4-Gbps speed (5:1 oversubscription) (default)
> - One port with dedicated rate mode and 8-Gbps speed plus
>   eleven ports with shared rate mode and 4-Gbps speed (10:1 oversubscription)
> - One port with dedicated rate mode and 4-Gbps speed plus
>   three ports with dedicated rate mode and 3-Gbps speed plus
>   eight ports with shared rate mode and 4-Gbps speed (2:1 oversubscription)
> - Twelve ports with dedicated rate mode and 1-Gbps speed

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