Cisco Systems DSC9148D8G48PK9 Extended BB_credits on Generation 1 Switching Modules

4-18
Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
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
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.
—SPEED LINK—
LINK-
—SPEEDLINK—
STATUS
1 56789
LINK— —SPEED
10 11 12 13 14234
12
LINK-
GIGABIT E THERNET
120479
Group 1 Group 2 Group 3
Extended credits
not supported