ISO-OSI 7-Layer Network Architecture
This lecture introduces the ISO-OSI layered architecture of Networks. According to the ISO standards, networks have
been divided into 7 layers depending on the complexity of the fucntionality each of these layers provide. The detailed
description of each of these layers is given in the notes below. We will first list the layers as defined by the
standard in the increasing order of function complexity:
- Physical Layer
- Data Link Layer
- Network Layer
- Transport Layer
- Session Layer
- Presentation Layer
- Application Layer
This layer is the lowest layer in the OSI model. It helps in the transmission of data between two machines that are
communicating through a physical medium, which can be optical fibres,copper wire or wireless etc. The following are the
main functions of the physical layer: