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Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
Chapter 4 Configuring Interface Buffers
Information About Interface Buffers
Cisco MDS 9124 Fabric Switch BB_Credit Buffers
Table 4-12 lists the BB_credit buffer allocation for MDS 9124 Fabric Switches.
Cisco MDS 9222i Multiservice Modular Switch BB_Credit Buffers
Table 4-13 lists the BB_credit buffer allocation for 18-port 4-Gbps Multiservice Modular switches.
Extended BB_Credits
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, Generation 3 and Generation 4 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.
Note Extended BB_credits are not supported on the Cisco MDS 9148 Fabric Switch, Cisco MDS 9134 Fabric
Switch, Cisco MDS 9124 Fabric Switch, the Cisco Fabric Switch for HP c-Class BladeSystem, and the
Cisco Fabric Switch for IBM BladeCenter.
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.
Note The ENTERPRISE_PKG license is required to use extended BB_credits on Generation 2, Generation 3
and Generation 4 switching modules. Also, extended BB_credits are not supported by ports in shared
rate mode.
Ta b l e 4-12 MDS 9124 Fabric Switch BB_Credit Buffer Allocation Defaults
BB_Credit Buffer Allocation Type
BB_Credit
Buffers Per
Port Group
BB_Credit Buffers Per Port
Defaults
ISL
1
1. ISL = E port or TE port.
Fx Port
Maximum user-configurable BB_credit buffers 64 61 61
Minimum user-configurable BB_credit buffers 2 1
Default BB_credit buffers 64 16 16
Ta b l e 4-13 18-Port 4-Gbps Fabric Switch BB_Credit Buffer Allocation Defaults
BB_Credit Buffer Allocation Type
BB_Credit
Buffers Per
Port Group
BB_Credit Buffers Per Port
Defaults
ISL
1
1. ISL = E port or TE port.
Fx Port
User-configurable BB_credit buffers 4509 250 16
