A router knows when the equipment attached to it changes, when it has problems, and when people change its configuration. When you make changes to your router via the console, or if a circuit has a problem, you'll probably notice messages such as
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial3/1, changed state to down
By default, these messages are dumped onto the console so that the administrator can figure out what is happening. If you're not staring at the console 24 hours a day, it's less than helpful. While the router can store log messages locally, it can also send these messages to another system for safekeeping. We'll start with the local logs and proceed to the more advanced remote logs.
The router can ...