Cisco Systems DSC9148D8G48PK9 manual Port 4-Gbps Fibre Channel Module BBCredit Buffers

Chapter 4 Configuring Interface Buffers

Information About Interface Buffers

24-Port 4-Gbps Fibre Channel Module BB_Credit Buffers

Table 4-6lists the BB_credit buffer allocation for 24-port 4-Gbps Fibre Channel switching modules.

Table 4-6 24-Port 4-Gbps Switching Module BB_Credit Buffer Allocation

	BB_Credit Buffers Per Port
	Dedicated Rate Mode		Shared Rate Mode
	4-Gbps Speed		4-Gbps Speed
BB_Credit Buffer Allocation	ISL1	Fx Port	Fx Port
Default BB_credit buffers	250	16	16
Maximum BB_credit buffers	250	250	16
Total number of BB_credits buffers per module	6000

1. ISL = E port or TE port.

The following considerations apply to BB_credit buffers on 24-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 24-port 4-Gbps Fibre Channel switching module consists of six ports. The ports in shared rate mode have a bandwidth oversubscription of 2:1 by default. However, some configurations of the shared ports in a port group can have a 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:

•Six ports with shared rate mode and 4-Gbps speed (2:1 oversubscription) (default)

•Two ports with dedicated rate mode and 4-Gbps speed plus

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

•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

•Three ports with dedicated rate mode and 4-Gbps speed plus

three ports with shared rate mode and 1-Gbps speed (see Figure 4-8)

Note For detailed configuration steps of this example, see the “Configuration Example for 24-Port4-Gbps Module Interfaces” section on page 3-49.

	Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
4-12	OL-29284-01, Release 6.x