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Lesson 2 Internet Protocol
Objective Identify the properties of Internet Protocol.

Internet Protocol Properties

Imagine you wake one morning in a strange land where everything is written in a language you do not understand. As you venture out, you quickly find you cannot accomplish even basic tasks.
Language is a protocol, and its rules tell us how to interpret what others say. The Internet has a protocol too, and its rules make sure data gets from computer to computer.
Internet Protocol
Internet Protocol (IP) underlies all communication over the Internet. It is responsible for:
  1. Describing an addressing mechanism for Internet computers
  2. Breaking data up into manageable pieces and moving them from source to destination

Internet Protocol version 4 (IPv4) became standard in 1981. Today, IP version (IPv6) is gaining acceptance as the next generation IP standard.


When you send data (email, for example), Linux breaks the data into little pieces called packets. Every packet contains information on where it's going (destination address), where it came from (source address), and a data payload.
Packet: A unit of information, usually composed of two parts: a header with controlling information and a body with actual information.
Gateways: Intermediate gateways route the IP packet to its destination host. Once there, the operating system reassembles all the packets into one unit and gives it to the appropriate program.
Gateway:An entrance into another network, responsible for routing packets into its own network or onto a peer network.

IP is a simple protocol, and thus does not take address all the possible problems in delivering messages. For instance, Internet Protocol can not:
  1. Guarantee packet delivery
  2. Guarantee packets arrive in the order they were sent
  3. Establish a reliable connection between destination and source
Other protocols, which you will learn about in the next few lessons, build on Internet Protocol and make it more reliable.
The next lesson describes an IP address.