Configuring Extended Bb_Credits; Enabling Buffer-To-Buffer State Change Number - 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
•
Note Extended BB_credits are not supported on the Cisco MDS 9124 Fabric Switch, Cisco MDS 9134 Fabric
Switch, the Cisco Fabric Switch for HP c-Class BladeSystem, and the Cisco Fabric Switch for IBM
BladeCenter.

Configuring Extended BB_credits

To configure extended BB_credits for a MDS-14/2 interface, for a Generation 2 switching module
interface (not including the Cisco MDS 9124 Fabric Switch), or for an interface in a Cisco MDS 9216i
switch, follow these steps:
Command
Step 1
switch# config t
switch(config)#
Step 2
switch(config)# fcrxbbcredit extended enable
switch(config)# no fcrxbbcredit extended
enable
Step 3
switch(config)# interface fc1/1
switch(config-if)#
Step 4
switch(config-if)# switchport fcrxbbcredit
extended 1500
switch(config-if)# no switchport
fcrxbbcredit extended 1500
Step 5
switch# do show interface fc3/2
fc3/2 is trunking
Hardware is Fibre Channel, SFP is short wave
laser w/o OFC (SN)
on

Enabling Buffer-to-Buffer State Change Number

The BB_SC_N field (word 1, bits 15-12) specifies the buffer-to-buffer state change (BB_SC) number.
The BB_SC_N field indicates that the sender of the port login (PLOGI), fabric login (FLOGI), or ISLs
(E or TE ports) frame is requesting 2^SC_BB_N number of frames to be sent between two consecutive
BB_SC send primitives, and twice the number of R_RDY primitives to be sent between two consecutive
BB_SC receive primitives.
OL-19445-02, Cisco MDS NX-OS Release 4.2(x)
Configure this feature in any port on a Generation 2 switch module. See the
BB_Credits" section on page 4-17
switching modules.
Port WWN is 20:82:00:05:30:00:2a:1e
Peer port WWN is 20:42:00:0b:46:79:f1:80
Admin port mode is auto, trunk mode is
Port mode is TE
Port vsan is 1
Speed is 2 Gbps
Transmit B2B Credit is 255
Receive B2B Credit is 1500
Receive data field Size is 2112
...
for more information on extended BB_credits on Generation 2
Purpose
Enters configuration mode.
Enables the extended BB_credits feature.
Disables (default) the extended BB_credits
feature.
Selects a Fibre Channel interface and enters
interface configuration submode.
Applies the extended BB_credit value of 1,500
credits to the selected interface. The valid range is
from 256 to 3,500 credits.
Clears the configured extended BB_credit
configuration for this port.
Displays the receive and transmit BB_credit
values along with other pertinent interface
information for this interface if the interface is in
the up state.
The receive BB_credit value reflects the
Note
extended BB_credit configuration, if
applicable.
Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
About Extended BB_Credits
"About Extended
4-19