[c-nsp] err-disable (Loopback test)

[Sam Stickland]

Hi,

We recently had a port on a C2950 go into the err-disable state for
failing the loopback test. Adding 'errdisable recovery cause loopback'
caused the switch to re-enable the port after a 300 second timer had
elasped.

But I'm curious - what is the loopback test that the port failed? It only
occured the once. Google failed to turn up any real answers.

Sam