Software Loopback with Connected Stack Cables: Examples • 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. # show switch stack-ports summary # Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In Status Length OK Active OK To LinkOK Loopback -------- ------ -------- -------- ---- ------ ---- --------- -------- 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 • Stack ports with a cable that works properly # show switch stack-ports summary # Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In Status Length OK Active OK To LinkOK Loopback -------- ------ -------- -------- ---- ------ ---- --------- -------- 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. Software Loopback with no Connected Stack Cable:
Example # show switch stack-ports summary # Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In Status Length OK Active OK To LinkOK Loopback -------- ------ -------- -------- ---- ------ ---- --------- -------- 1/1 Absent None No cable No No No 1 Yes 1/2 Absent None No cable No No No 1 Yes Finding a Disconnected Stack Cable: Example Stack cables connect all stack members. Port 2 on Switch 1 connects to Port 1 on Switch 2. This is the port status for the members:
# show switch stack-ports summary # Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In Status Length OK Active OK To LinkOK Loopback -------- ------ -------- -------- ---- ------ ---- --------- -------- Managing Switch Stacks Software Loopback with Connected Stack Cables: Examples Managing Switch Stacks 20