Summary

In this chapter, we focused on the transport layer (or Layer 4) of the OSI model, specifically the two predominant protocols in this layer, TCP and UDP. We started with an overview of the transport layer. We then evaluated TCP, a connection-oriented protocol. We saw that in order to achieve reliability, TCP sequences and acknowledges every octet. We now understand how, in addition to transporting data, TCP monitors the transmission, and provides not only flow control, but congestion control as well. We also took a closer look at the header, along with the eight control flags, then reviewed how window scaling works.

Along with TCP, we looked at the other predominant transport layer protocol, UDP, which ensures fast transportation of time-sensitive data and protocols such as DHCP and DNS. We reviewed the details of the four-field UDP header, which provides enough information to deliver data with no additional overhead.

Now that you have a solid understanding of TCP, the...