Learning Resources
Lesson
Networks have many different kinds of hardware and software. They need to be able to communicate with each other. For example, they need to have a common language, a common way of sending and receiving information, and a way to let the other device know when something is received and if it was ok.
All of these commonalities are collected into sets of rules called protocols. There are many different types of protocols. Generally speaking, they operate on 7 different network layers. The layers, defined by the International Organization for Standardization, are called the Open Systems Interconnection (OSI) model. Each layer has to communicate with the ones below and above it.
Figure OSI Network Layers
Physical layer. This is the parts of the device and the cables connecting devices together. The electrical signals that carry data are also part of this layer. The protocol describes how they need to communicate with each other and with the next layer.
Data Link Layer. This layer assigns meanings to the signals. It decides the size of data that can be sent, the format, and sets the way errors in the data are detected and corrected.
Network Layer. This layer defines how two different kinds of networks talk to each other
Transport Layer. Breaks data into smaller packets for distribution to other nodes (remember, node means computer, router, switch, etc)
Session Layer. Creates the sessions that allow data to be sent to another node
Presentation Layer. Codes and decodes data that is sent to a node
Application Layer. Allows the user to run an application such as email a browser, or word processor. The application makes a request for data, or sends data. This is the layer you normally interact with.
The internet, and many local area networks communicate using a protocol called IP or Internet Protocol. The diagram below shows how IP networks relate to the OSI model.
Figure IP Network and the OSI Model
Physical is the same as in the OSI model
Media Access Control (MAC) is the network adapter driver. Often referred to as the MAC address of the network card. The Mac address is a 48 bit number unique to each card and is of the form nn:nn:nn:nn:nn:nn (for example 11:5C:05:F4:40:55). LAN Drivers are operating system protocols. This is how Windows, for example, talks to the network card.
IP is Internet Protocol. It describes how the networks communicate with each other. The IP address uniquely defines each device on the network. IP addresses (covered in Unit 2) are of the form nnn.nnn.nnn.nnn, for example 203.141.5.21
TCP is Transport Control Protocol. It is provides the means for applications to access the network. It manages multiple events simultaneously. It takes care of error correction.
SNMP (Simple Network Management Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transport Protocol), and Telnet are sessions that run on the computer and access the network through TCP/IP. These protocols are used by the NFS (next layer) to give access to the network by other applications such as browsers and email.
Network File System (NFS) provides the protocols for file organization and access on a TCP/IP network
For Additional Information
If you would like additional information, the following are good starting points
Activity
Please complete all activities
- Create an animated gif that moves a coloured circle up and down the TCP/IP network layers
- Create an entry in your course portfolio and import the graphic
- Publish the entry to your course web
Test Yourself
There is no self test for this lesson.