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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 type: 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