Manually Inserting Entries Into Alpa Cache; Displaying The Alpa Cache Contents; Clearing The Alpa Cache; Buffer Credits - HP Cisco MDS 9020 - Fabric Switch Configuration Manual

Buffer Credits

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

Manually Inserting Entries into ALPA Cache

To manually insert entries into the ALPA cache, follow these steps:
Command
Step 1
switch# config t
Step 2
switch(config)# tlport alpa-cache interface
fc1/2 pwwn 22:00:00:20:37:46:09:bd alpa 0x02
Step 3
switch(config)# tlport alpa-cache interface
fc1/3 pwwn 22:00:00:20:37:46:09:bd

Displaying the ALPA Cache Contents

The show tlport alpa-cache command displays the contents of the ALPA cache.
switch# show tlport alpa-cache
---------------------------------------------------------
alpa
---------------------------------------------------------
0x02
0x04
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:
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•
•
•
•
•
•

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.
Cisco MDS 9000 Family CLI Configuration Guide
12-32
pWWN
22:00:00:20:37:46:09:bd
23:00:00:20:37:46:09:bd
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
Purpose
Enters configuration mode.
Configures manual entries into the ALPA cache.
Removes this entry from the ALPA cache.
Interface
fc1/2
fc1/2
Chapter 12 Configuring Interfaces
OL-16184-01, Cisco MDS SAN-OS Release 3.x