re's a longer period of time from the point at which the bus's nose enters an intersection and its tail exits, resulting in more latency. On the other hand, the Ferrari will take much less time to make it through the intersection. Similarly, if there is mass congestion at the intersection, the bus will have to wait until the traffic clears before it can cross, while the police officer is likely to let the Ferrari use the shoulder to bypass the congestion. Similarly, in packet switching, each packet basically defines the number of passengers that can be carried (the number of bits) and the level of navigational controls (the control information in the overhead defin- ing how to handle congestion and loss). Connectionless Versus Connection-Oriented Packet-Switched Networks There are two forms of packet-switched networks: connectionless and connection oriented. Connectionless Packet-Switched Networks You can picture connectionless net- works by using a postal service analogy: Bob writes a letter, puts it in an envelope, and addresses the envelope. His carrier does not care in the least what it says on the envelope because she knows where she is taking that envelope. It's going to the next point of presence, which is the local post office. The local post office will be concerned with the destination zip code, but it doesn't care at all about the name or street address on the envelope. It simply wants to know what regional center to route it to. The regional center cares about the destination city, and the destination local post office cares about the actual street address because it needs to assign the letter to the right carrier. The carrier cares about the name SO that the letter finds its way into the right mailbox. If the letter ends up in someone else's mailbox, the Chapter 3 Establishing Communications Channels unintended recipient holds the ultimate responsibility for error control because he or she is the endpoint. In comparison, if Bob sends that letter via fax, it is connection- oriented: The connection to 