Cisco Systems DSC9148D8G48PK9 manual Default BBcredit buffers 500 Maximum BBcredit buffers

Chapter 4 Configuring Interface Buffers

Information About Interface Buffers

•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

24-Port 8-Gbps Fibre Channel Module BB_Credit Buffers

Table 4-3lists the BB_credit buffer allocation for the 24-port 8-Gbps Fibre Channel switching module.

Table 4-3 24-Port 8-Gbps Switching Module BB_Credit Buffer Allocation

	BB_Credit Buffers Per Port
	Dedicated Rate Mode		Shared Rate Mode
	8-Gbps Speed		8-Gbps Speed
BB_Credit Buffer Allocation	ISL	Fx Port	Fx Port
Default BB_credit buffers	500	32	32
Maximum BB_credit buffers	5001	5001	32

Total Number of BB_Credit Buffers per Module

Ports 1 through 12

Ports 13 through 24

6000

6000

1. When connected to Generation 1 modules, reduce the maximum BB_credit allocation to 250.

The following guidelines apply to BB_credit buffers on 24-port 8-Gbps Fibre Channel switching modules:

•BB_credit buffers allocated for ports 1 through 12 and 13 through 24 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.

Each port group on the 24-port 8-Gbps Fibre Channel switching module consists of three 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 24-port 8-Gbps Fibre Channel switching modules:

•Three ports with shared rate mode and 8-Gbps speed (2:1 oversubscription) (default)

•One port with dedicated rate mode and 8-Gbps speed plus

two ports with shared rate mode and 8-Gbps speed (4:1 oversubscription)

•One port with dedicated rate mode and 8-Gbps speed plus one port with dedicated rate mode and 4-Gbps speed plus

one port with shared rate mode and 8-Gbps speed (10:1 oversubscription)

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

one port with shared rate mode and 8-Gbps speed (2:1 oversubscription)

	Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
4-8	OL-29284-01, Release 6.x