Cisco Systems DSC9148D8G48PK9 manual BBCredit Buffers Per Port, Shared Rate Mode, Fx Port

Chapter 4 Configuring Interface Buffers

Information About Interface Buffers

When you configure port mode to auto or E on a Generation 3 module, one or two of the ports will not come up for the following configuration:

•Port Mode: auto or E for the first half of the ports, the second half of the ports or for all of the ports

•Rate Mode: dedicated

•Buffer Credits: default value

When you configure port mode to auto or E for all ports in the global buffer pool, you need to reconfigure buffer credits on one or more of the ports. The total number of buffer credits configured for all the ports in the global buffer pool should be reduced by 64.

48-Port 8-Gbps Advanced Fibre Channel Module BB_Credit Buffers

Table 4-1lists the BB_credit buffer allocation for the 48-port 8-Gbps Advanced Fibre Channel switching module..

Table 4-1	48-Port 8-Gbps Advanced 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		250 for 48	32	32
		port
		500 for 32
		port
Maximum BB_credit buffers		500	500	32

The following guidelines apply to BB_credit buffers on 32/48-port Advanced 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 500 buffers for dedicated rate mode or 32 buffers for shared rate mode.

•Performance buffers are not supported on this module.

•The buffers should not be allocated automatically.

Each port group on the 32/48-port Advanced 8-Gbps Fibre Channel switching module consists of four/six ports. The ports in shared rate mode in a port group can have a maximum bandwidth oversubscription of 1.5:1 considering that each port group has 32-Gbps bandwidth. In case of 32 Port version, each port group of 4 ports has sufficient bandwidth (32 Gbps) to handle the line rate traffic without any oversubscription.

The following example configurations are supported by the 48-port Advanced 8-Gbps Fibre Channel switching modules:

•Six ports with shared rate mode and 8-Gbps speed (1.5:1 oversubscription) (default).

•Two port with dedicated rate mode and 8-Gbps speed plus four ports with shared rate mode and 8-Gbps speed (2:1 oversubscription).

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