When I unplug LAN cable from interface fa0/0 why interface still up but protocol down ?
It is default ? or we can set ?
Thank you in advance.
It is the default behavior of IOS routers such as the 1841 that if the FastEthernet interface is not plugged into some device then the interface will show as interface up and line protocol is down.
If you have keepalives disabled, then the link will stay up.
Check your config, under that interface, for a "no keepalive" statement
Also make sure you are looking at the right interface ....