Network Packets

The information tranmitted across a network is a combiniation of the numbers one and zero. In order for these numbers to be meaningful, rules are established regarding the organization of the numbers. These rules are based on a basic unit of information called a packet.

Packets may have the following components:

The above components are combined into three sections: header, data, and trailer.

Header Data Field Trailer
Generic Packet Format

The rules for the format of each section depend upon which network protocol is being used. In many cases there are several protocols involved. Each protocol would add additional information to the packet.

Destination
Address
Source
Address
Protocol
Type Field
IP Header IP Data CRC
Error Checking
Ethernet Frame around IP datagram

Every Protocol has a method for distingishing computers from each other. This process is called addressing. This address information must be included in the packets so that the information goes to the correct destination. The addressing methods vary between the different protocols.