1.9. Summary

This chapter has been a whirlwind tour of concepts in network architecture and design in general, plus the TCP/IP protocol suite in particular that we discuss in detail in later chapters. The Internet architecture was designed to interconnect different existing networks and provide for a wide range of services and protocols operating simultaneously. Packet switching using datagrams was chosen for its robustness and efficiency. Security and predictable delivery of data (e.g., bounded latency) were secondary concerns.

Based on their understanding of layered and modular software design in operating systems, the early implementers of the Internet protocols adopted a layered design that employs encapsulation. The three main layers in the TCP/IP protocol suite are the network layer, transport layer, and application layer, and we mentioned the different responsibilities of each. We also mentioned the link layer because it relates so closely with the TCP/IP suite. We shall discuss each in more detail in subsequent chapters.