Originally Posted by creatorrr
I know the switchport, want to find hostname or IP or Mac address of the coresponding host, anything. Would like to avoid tracing the cable or packet sniffing utilities, if that is posible...
show vlan - will show you switchport to vlan mapping.
show mac-address-table - will show you the learned MAC address of each device connected to the switch ports along with MAC addresses learned from other VLAN's via any trunked ports.
show arp - will tell you the IP address to MAC mapping. But if the switch is configured as layer 2 only, then show arp will not be of much use.
FWIW: When I see switchports flapping (as compared to a routing protocol like OSPF flapping), its usually one of the following:
1) Cable is bad (rj45 pins might be corroded, bad crimp on pins 1,2,3,6)
2) NIC card of device connected to flapping port
3) Speed mismatch (set the speed/duplex manually at both ends)
There are other possibilities that might cause port flapping, but I always check the above first. Especially the cable and NIC