Network Software
By the end of this lesson, you should be able to: state the network application software state and explain the seven layers of OSI model
Network software
include:
Network Operating Systems
Most servers run on Network Operating System. This OS is used to control and serve client computers
Functions of Network Operating Systems
Examples of Network Operating System
Network Protocols
A protocol is a set of rules used that guide communication of networked devices
Due to the fact that computers and various devices on a network may be running on the different operating systems, the ISO came up OSI (Open Systems Interconnection ) model to enable such devices to interoperate.
The OSI model has 7 main layers:
NB: Each of the above layers uses a package of protocols:
Application Layer
This layer uses protocols such as HTTP, SMTP, FTP, Telnet, etc. It provides services for network applications. This is the layer at which network applications operate e.g internet browsers, email apps,
HTTP/S - used for web surfing through browsers
SMTP - used for email through email apps
FTP - File transfer
Presentation Layer
This layer receives data from the application layer. It converts this data to machine-readable form. So, this layer does more of data translation. It also compresses the translated data so as to be transmitted faster. This layer encrypts data before transmission. Secure Socket Layer (SSL) Protocol is for encryption and decryption.
Session Layer
This layer helps in:
This layer uses APIs to help it perform the above functions. NETBIOS is an example of API(Application Programming Interface)
Note: The web browsers perform all functions of the application, presentation, and session layer
Transport Layer
Controls the reliability of communication through:
Protocols at this layer include: TCP and UDP
UDP(User Datagram Protocol) is faster than TCP
TCP - Deals with a connection-oriented transmission
UDP - Deals with a connectionless transmission
Network Layer
Functions of the network layer:
Data Link Layer
Functions
Physical layer