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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 5 Managing Switch Stacks
Troubleshooting Stacks
Hardware Loopback
The show platform stack ports buffer privileged EXEC command output shows the hardware loopback
values.
Switch# show platform stack ports buffer
Stack Debug Event Data Trace
==============================================================
Event type LINK: Link status change
Event type RAC: RAC changes to Not OK
Event type SYNC: Sync changes to Not OK
==============================================================
Event Stack Stack PCS Info Ctrl-Status Loopback Cable
Count Port IOS / HW length
========= ===== =================================== =========== ======== ========
Event type: LINK OK Stack Port 1
0000000011 1 FF08FF00 860302A5 AA55FFFF FFFFFFFF 1CE61CE6 Yes/Yes No cable
0000000011 2 FF08FF00 86031805 55AAFFFF FFFFFFFF 1CE61CE6 Yes/Yes No cable
Event type: LINK OK Stack Port 2
0000000012 1 FF08FF00 860302A5 AA55FFFF FFFFFFFF 1CE61CE6 Yes/Yes No cable
0000000012 2 FF08FF00 86031805 55AAFFFF FFFFFFFF 1CE61CE6 Yes/Yes No cable
Event type: RAC
0000000013 1 FF08FF00 860302A5 AA55FFFF FFFFFFFF 1CE61CE6 Yes/Yes No cable
0000000013 2 FF08FF00 86031805 55AAFFFF FFFFFFFF 1CE61CE6 Yes/Yes No cable
On a Catalyst 3750 member,
• If at least one stack port has an connected stack cable, the Loopback HW value for both stack ports
is No.
• If neither stack port has an connected stack cable, the Loopback HW value for both stack ports is Yes.
On a Catalyst 3750-E or Catalyst 3750-X member,
• If a stack port has an connected stack cable, the Loopback HW value for the stack port is No.
• If the stack port does not have an connected stack cable, the Loopback HW value for the stack port
is Yes.
Hardware Loopback Example: LINK OK event
On a Catalyst 3750 switch:
Switch# show platform stack ports buffer
Stack Debug Event Data Trace
=========
=====================================================
Event type LINK: Link status change
Event type RAC: RAC changes to Not OK
Event type SYNC: Sync changes to Not OK
==============================================================
Event Stack Stack PCS Info Ctrl-Status Loopback Cable
Count Port IOS / HW length
========= ===== =================================== =========== ======== ========
Event typ
e: LINK OK Stack Port 1
0000000008 1 FF08FF00 8603F083 55AAFFFF FFFFFFFF 0CE60C10 No /No 50 cm
0000000008 2 FF08FF00 0001DBDF 01000B00 FFFFFFFF 0CE60C10 No /No No cable
Event type: RAC
0000000009 1 FF08FF00 8603F083 55AAFFFF FFFFFFFF 0CE60C10 No /No 50 cm
0000000009 2 FF08FF00 0001DC1F 02000100 FFFFFFFF 0CE60C10 No /No No cable
