What shotuld the interface status show when troubleshooting a bad T1 serial card with a loopback plug?
I had a guy disconnect the T1 cable from the router, plug in the loopback and did a show interface brief and saw the interface in question (s0/0/0) showing UP/DOWN. I did have the guy unplug everything and when I checked again the same interface was DOWN/DOWN. I expected to see it show UP/UP with the loopback so I could run extended pings but obviously when an interface is UP/DOWN you cannot ping the interface IP address and expect replys. Why would a serial interface show UP/DOWN with a loopback plug in the serial port? Could the loopback plug be improperly terminated? or does UP/DOWN mean something?
