Now we get to the fun, the world of routing. This chapter discusses router configurations, including static routing and dynamic routing protocols such as Routing Information Protocol (RIP), Enhanced Interior Gateway Routing Protocol (EIGRP), Open Shortest Path First (OSPF), and the Border Gateway Protocol (BGP). Routing can be compared to mail delivery. You identify the recipient of the mail by writing the name and address, and you identify yourself as the sender with your address. You put your letter in the mailbox to be picked up by the mailman. The mailman takes your letter to the post office, where it is determined how to route your letter to its destination. Your letter may pass through many post offices along the way. If there is a problem along the way, the letter is routed back to you as the sender.