Software Loopback: Examples In a stack with three members, stack cables connect all 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 -------- ------ -------- -------- ---- ------ ---- --------- -------- 1/1 OK 3 50 cm Yes Yes Yes 1 No 1/2 OK 2 3 m Yes Yes Yes 1 No 2/1 OK 1 3 m Yes Yes Yes 1 No 2/2 OK 3 50 cm Yes Yes Yes 1 No 3/1 OK 2 50 cm Yes Yes Yes 1 No 3/2 OK 1 50 cm Yes Yes Yes 1 No If you disconnect the stack cable from Port 1 on Switch 1, these messages appear: 01:09:55: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 3 has changed to state DOWN 01:09:56:
%STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 1 has changed to state DOWN # 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 No 1/2 OK 2 3 m Yes Yes Yes 1 No 2/1 OK 1 3 m Yes Yes Yes 1 No 2/2 OK 3 50 cm Yes Yes Yes 1 No 3/1 OK 2 50 cm Yes Yes Yes 1 No 3/2 Down None 50 cm No No No 1 No If you disconnect the stack cable from Port 2 on Switch 1, the stack splits. Switch 2 and Switch 3 are now in a two-member stack connected through stack cables:
# show sw stack-ports summary # Sw#/Port# Port Neighbor Cable Link Link Sync #Changes In Status Length OK Active OK To LinkOK Loopback -------- ------ -------- -------- ---- ------ ---- --------- -------- 2/1 Down None 3 m No No No 1 No 2/2 OK 3 50 cm Yes Yes Yes 1 No 3/1 OK 2 50 cm Yes Yes Yes 1 No 3/2 Down None 50 cm No No No 1 No Switch 1 is a standalone switch: # 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 Managing Switch Stacks Software Loopback:
Examples Managing Switch Stacks 19