Choosing Shipping Options When Transporting the Goods over the (Network) Roadway

Chapter 9. Choosing Shipping Options When Transporting the Goods over the (Network) Roadway

What You Will Learn

After reading this chapter, you should be able to

• List the main features of TCP

• Explain the TCP error recovery process

• Describe why a computer needs to use multiple TCP port numbers

• Explain the need for well-known TCP port numbers

• Explain the process and benefits of segmentation

Tons of businesses around the world use transportation companies to distribute their products. For instance, most small retail stores order goods from wholesalers, but a third company, a shipping company, actually picks up the products at the wholesaler and delivers them to the retailer. Likewise, when you order something over the Internet, typically one of the larger shipping companies, such as FedEx and UPS in the U.S., actually transports the product to your house.

This business model works well. The shipping companies of the world can build large fleets of trucks, planes, boats, donkeys, or whatever is needed to deliver the packages. They can deliver the goods for much less than each company trying to build its own distribution system. So, the companies that need their goods shipped save money, and the shippers make money.

A similar thing happens with application layer protocols and transport layer protocols in networking. The application layer protocols need to send and receive messages to and from another computer. As seen in Chapter 8, "Shipping Goods over a (Network) Roadway," some of those messages are just overhead, and some contain the actual end user data. Lots of application layer protocols need the same basic services to transport their messages across the network to another computer. Similar to companies that use shippers, the application layer protocols do not want to worry about the details of how the data gets between the computers. They just want to give the data to someone else, with the expectation that the data will be delivered to the application layer software at the destination computer.

In this chapter, you'll learn about how transport layer protocols perform several important functions on behalf of the myriad of application layer protocols, including the delivery of application layer messages and data between two computers.