Module 9: TCP/IP Protocol Suite and IP Addressing Overview

Overview
The Internet was developed to provide a communication network that could function in wartime. Although the Internet has evolved from the original plan, it is still based on the TCP/IP protocol suite. The design of TCP/IP is ideal for the decentralized and robust Internet. Many common protocols were designed based on the four-layer TCP/IP model.


It is useful to know both the TCP/IP and OSI network models. Each model uses its own structure to explain how a network works. However, there is much overlap between the two models. A system administrator should be familiar with both models to understand how a network functions.

Any device on the Internet that wants to communicate with other Internet devices must have a unique identifier. The identifier is known as the IP address because routers use a Layer 3 protocol called the IP protocol to find the best route to that device. The current version of IP is IPv4. This was designed before there was a large demand for addresses. Explosive growth of the Internet has threatened to deplete the supply of IP addresses. Subnets, Network Address Translation (NAT), and private addresses are used to extend the supply of IP addresses. IPv6 improves on IPv4 and provides a much larger address space. Administrators can use IPv6 to integrate or eliminate the methods used to work with IPv4.

In addition to the physical MAC address, each computer needs a unique IP address to be part of the Internet. This is also called the logical address. There are several ways to assign an IP address to a device. Some devices always have a static address. Others have a temporary address assigned to them each time they connect to the network. When a dynamically assigned IP address is needed, a device can obtain it several ways.

For efficient routing to occur between devices, issues such as duplicate IP addresses must be resolved.

This module covers some of the objectives for the CCNA 640-801, INTRO 640-821, and ICND 640-811 exams.

Students who complete this module should be able to perform the following tasks:

• Explain why the Internet was developed and how TCP/IP fits the design of the Internet
• List the four layers of the TCP/IP model
• Describe the functions of each layer of the TCP/IP model
• Compare the OSI model and the TCP/IP model
• Describe the function and structure of IP addresses
• Understand why subnetting is necessary
• Explain the difference between public and private addressing
• Understand the function of reserved IP addresses
• Explain the use of static and dynamic addressing for a device
• Understand how dynamic addresses can be assigned with RARP, BootP, and DHCP
• Use ARP to obtain the MAC address to send a packet to another device
• Understand the issues related to addressing between networks