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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter5 Managing Switch Stacks
Troubleshooting Stacks
Software Loopback Example: No Connected StackWise Cable
Catalyst 3750 switch port status:
Switch# show switch stack-ports summary
Switch#/ Stack Neighbor Cable Link Link Sync # In
Port# Port Length OK Active OK Changes Loopback
Status To LinkOK
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 Absent None No cable Yes No Yes 1 Yes
1/2 Absent None No cable Yes No Yes 1 Yes
Catalyst 3750-E switch port status:
Switch# show switch stack-ports summary
Switch#/ Stack Neighbor Cable Link Link Sync # In
Port# Port Length OK Active OK Changes Loopback
Status To LinkOK
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 Absent None No cable No No No 1 Yes
1/2 Absent None No cable No No No 1 Yes
Software Loopback Examples: Connected StackWise Cables
On Port 1 on Switch 1, the port status is Down, and a cable is connected.
On Port 2 on Switch 1, the port status is Absent, and no cable is connected.
Switch# show switch stack-ports summary
Switch#/ Stack Neighbor Cable Link Link Sync # In
Port# Port Length OK Active OK Changes Loopback
Status To LinkOK
-------- ------ -------- -------- ---- ------ ---- --------- --------
1/1 Down None 50 Cm No No No 1 No
1/2 Absent None No cable No No No 1 No
In a physical loopback, a cable connects both stack ports on a switch. You can use this configuration
to test
Cables on a switch that is running properly
StackWise ports with a cable that works properly
Switch# show switch stack-ports summary
Switch#/ Stack Neighbor Cable Link Link Sync # In
Port# Port Length OK Active OK Changes Loopback
Status To LinkOK
-------- ------ -------- -------- ---- ------ ---- --------- --------
2/1 OK 2 50 cm Yes Yes Yes 1 No
2/2 OK 2 50 cm Yes Yes Yes 1 No
The port status shows that
Switch 2 is a standalone switch.
The ports can send and receive traffic.