I have an extremly annoying question that I cannot seem to find the answer to. I know that when an interface is shut down or the cable is removed, the interfaces will immediately go down. But what technology ensures that the other side knows that the link is down?
I mean, the router/switch that you issue the shutdown command on will know that the interface is down because you issued the shutdown command on it, but how does the other side of the link know what you just did?
And is it the same technology that makes sure that you know if the cable has been removed or damaged so that the routers/switches know that the link is down?