About Extended Bb_Credits - Cisco MDS 9000 Series Configuration Manual

Chapter 4 Configuring Interface Buffers
S e n d d o c u m e n t a t i o n c o m m e n t s t o m d s f e e d b a c k - d o c @ c i s c o . c o m
Table 4-11
BB_Credit Buffer Allocation Type
User-configurable BB_credit buffers
1. ISL = E port or TE port.

About Extended BB_Credits

Extended BB_credits are not supported on the Cisco MDS 9124 Fabric Switch, Cisco MDS 9134 Fabric
Note
Switch, the Cisco Fabric Switch for HP c-Class BladeSystem, and the Cisco Fabric Switch for IBM
BladeCenter.
To facilitate BB_credits for long-haul links, the extended BB_credits feature allows you to configure the
receive buffers above the maximum value on all Generation 2 and Generation 3 switching modules.
When necessary, you can reduce the buffers on one port and assign them to another port, exceeding the
default maximum. The minimum extended BB_credits per port is 256 and the maximum is 4095.
In general, you can configure any port in a port group to dedicated rate mode. To do this, you must first
release the buffers from the other ports before configuring larger extended BB_credits for a port.
The ENTERPRISE_PKG license is required to use extended BB_credits on Generation 2 and Generation
Note
3 switching modules. Also, extended BB_credits are not supported by ports in shared rate mode.
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
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:
•
OL-19445-02, Cisco MDS NX-OS Release 4.2(x)
18-Port 4-Gbps Modular Switch BB_Credit Buffer Allocation Defaults
Extended BB_credits on Generation 1 Switching Modules, page 4-17
Extended BB_credits on Generation 2 and Generation 3 Switching Modules, page 4-18
Obtain the ENTERPRISE_PKG license (see the Cisco MDS 9000 Family NX-OS Licensing Guide).
BB_Credit
Buffers Per
Port Group
4509
Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
About Extended BB_Credits
BB_Credit Buffers Per Port
Defaults
1
ISL Fx Port
250 16
4-17