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
12-32
Cisco MDS 9000 Family CLI Configuration Guide
OL-16184-01, Cisco MDS SAN-OS Release 3.x
Chapter 12 Configuring Interfaces
Buffer Credits
Manually Inserting Entries into ALPA Cache
To manually insert entries into the ALPA cache, follow these steps:
Displaying the ALPA Cache Contents
The
show tlport alpa-cache
command displays the contents of the ALPA cache.
switch#
show tlport alpa-cache
---------------------------------------------------------
alpa pWWN Interface
---------------------------------------------------------
0x02 22:00:00:20:37:46:09:bd fc1/2
0x04 23:00:00:20:37:46:09:bd fc1/2
The first entry indicates that if a device with a pWWN of 22:00:00:20:37:46:09:bd is exported on TL
port fc1/2, then the pWWN is allocated an alpa 0x02 (if available).
Clearing the ALPA Cache
The
clear tlport alpa-cache
command clears the entire content of the ALPA cache.
Buffer Credits
Fibre Channel interfaces use buffer credits to ensure all packets are delivered to their destination. This
section describes the different buffer credits available on the Cisco MDS Family switches and includes
the following topics:
•
About Buffer-to-Buffer Credits, page 12-32
•
Configuring Buffer-to-Buffer Credits, page 12-33
•
About Performance Buffers, page 12-34
•
Configuring Performance Buffers, page 12-34
•
About Extended BB_credits, page 12-34
•
Configuring Extended BB_credits, page 12-36
•
Displaying BB_Credit Information, page 12-37
About Buffer-to-Buffer Credits
Buffer-to-buffer credits (BB_credits) are a flow control mechanism to ensure that FC switches do not
run out of buffers, because switches must not drop frames. BB_credits are negotiated on a per-hop basis.
Command
Purpose
Step 1
switch#
config t
Enters configuration mode.
Step 2
switch(config)#
tlport alpa-cache interface
fc1/2 pwwn 22:00:00:20:37:46:09:bd alpa 0x02
Configures manual entries into the ALPA cache.
Step 3
switch(config)#
tlport alpa-cache interface
fc1/3 pwwn 22:00:00:20:37:46:09:bd
Removes this entry from the ALPA cache.
