48-Port 4-Gbps Fibre Channel Module BB

Table 14-5 lists the BB_credit buffer allocation for 48-port 4-Gbps Fibre Channel switching modules.

Table 14-5 48-Port 4-Gbps Switching Module BB_Credit Buffer Allocation
BB_Credit Buffer Allocation	BB_Credit Buffers Per Port
	Dedicated Rate Mode 4-Gbps Speed		Shared Rate Mode 4-Gbps Speed
	ISL¹	Fx Port	Fx Port
Default BB_credit buffers	125	16	16
Maximum BB_credit buffers	250	250	16
Total number of BB_credit buffers per module	6000

¹ISL = E port or TE port.

The following considerations apply to BB_credit buffers on 48-port 4-Gbps Fibre Channel switching modules:

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.

Each port group on the 48-port 4-Gbps Fibre Channel switching module consists of 12 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 48-port 4-Gbps Fibre Channel switching modules:

Twelve ports with shared rate mode and 4-Gbps speed (4:1 oversubscription) (default)

One port with dedicated rate mode and 4-Gbps speed plus
11 ports with shared rate mode and 4-Gbps speed (5:1 oversubscription)

One port with dedicated rate mode and 4-Gbps speed plus
11 ports with shared rate mode and 2-Gbps speed (2.5:1 oversubscription)

Two ports with dedicated rate mode and 2-Gbps speed plus
10 ports with shared rate mode and 4-Gbps speed (5:1 oversubscription)

Two ports with dedicated rate mode and 2-Gbps speed plus
10 ports with shared rate mode and 2-Gbps speed (2.5:1 oversubscription)

Twelve ports with dedicated rate mode and 1-Gbps speed

Three ports with dedicated rate mode and 4-Gbps speed plus
four ports with shared rate mode and 1-Gbps speed plus
five ports put out-of-service

Six ports with dedicated rate mode and 2-Gbps speed plus
four ports with shared rate mode and 1-Gbps speed plus
two ports put out-of-service

48-Port 4-Gbps Fibre Channel Module BB_Credit Buffers