A LAN is connected to VLAN configured in sw3560 which usually gives error of loopback and shutting down the port.
when we go through CNA , a notification gives a msg
" check configuration of the switch , also make sure devices connected to the sw are not mirroring the traffic back to switch. Enable this port again.
Fastethernet 0/5 is down, line protocol is down (err-disabled)."
now after enabling the port, it is working fine again. this problem is coming only in single vlan (port) among 6 vlan's.
we have changed cable and even sw also.
so, loopback and mirroring concept is similar or differ, pse clear and also suggest the possible solution.