Cisco Systems DSC9148D8G48PK9 manual Extended BBcredits on Generation 1 Switching Modules

Chapter 4 Configuring Interface Buffers

Information About Interface Buffers

All ports on the Generation 2 and Generation 3 switching modules support extended BB_credits. There are no limitations for how many extended BB_credits you can assign to a port (except for the maximum and minimum limits). If necessary, you can take interfaces out of service to make more extended BB_credits available to other ports.

You can use the extended BB_credits flow control mechanism in addition to BB_credits for long-haul links.

This section includes the following topics:

•Extended BB_credits on Generation 1 Switching Modules, page 4-18

•Extended BB_credits on Generation 2 and Generation 3 Switching Modules, page 4-19

Extended BB_credits on Generation 1 Switching Modules

The BB_credits feature allows you to configure up to 255 receive buffers on Generation 1 switching modules. To facilitate BB_credits for long haul links, you can configure up to 3,500 receive BB_credits on a Fibre Channel port on a Generation 1 switching module.

To use this feature on Generation 1 switching modules, you must meet the following requirements:

•Obtain the ENTERPRISE_PKG license. See the Cisco MDS 9000 Family NX-OS Licensing Guide.

•Configure this feature in any port of the full-rate 4-port group in either the Cisco MDS 9216i Switch or in the MPS-14/2 module (see Figure 4-9).

Figure 4-9 Port Group Support for the Extended BB_Credits Feature

12

LINK- LINK-

1	2	3	4		5	6	7	8	9	10	11	12	13	14
STATUS														GIGABIT E THERNET
LINK—			—SPEED	LINK—					—SPEED	LINK—				—SPEED
	Group 1					Group 2				Group 3

Extended credits

not supported

120479

The port groups that support extended credit configurations are as follows:

–Any one port in ports 1 to 4 (identified as Group 1).

–Any one port in ports 5 to 8 (identified as Group 2).

–Any one port in ports 9 to 12 (identified as Group 3).

Note The last two Fibre Channel ports (port 13 and port 14) and the two Gigabit Ethernet ports do not support the extended BB_credits feature.

•Explicitly enable this feature in the required Cisco MDS switch.

•Disable the remaining three ports in the 4-port group if you need to assign more than 2,400 BB_credits to the first port in the port group.

–If you assign less than 2,400 extended BB_credits to any one port in a port group, the remaining three ports in that port group can retain up to 255 BB_credits based on the port mode.

	Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
4-18	OL-29284-01, Release 6.x