Table of Contents
Physical Layer of OSI Model
Lowest layer of OSI model is physical layer. Major concerns of this layer is to deal with the physical medium which is used for data communication between sender and receiver node or host or devices. This physical medium is also known as transmission media this may be copper wire, fiber in case of wired network and wireless network etc.
Functions of Physical Layer
Different functions of physical layer are as follow
1.Specification of Hardware: Physical layer keeps the track of the transmission media such as physical cables, network interface cards, wireless radios, etc.
2. Encoding and Signaling: Encoding of bits in the medium is also decided by physical layer.
3. Data Transmission and Reception: Physical layer is also responsible for transmitting each bit of data and ensures the transmission of each bit with a high probability. The transmission of the bits is not completely reliable as their is no error correction in this layer.
4.Topology and Network Design: The network design is also a part of the physical layer. Different issues related to this part are such as Which part of the network is the router going to be placed, where the switches will be used, where we will put the hubs, how many machines is each switch going to handle, what server is going to be placed where, and many such concerns are to be taken care of by the physical layer.
Basic Terminology used at Physical Layer
Bit Rate , Baud rate, Frequency, Bandwidth , transmission media are some basic terms used at this layer. Let us see the meaning of each term one by one.
Bit rate : In computer network bit rate means number of bits transmitted per second.
Baud rate: Baud rate is number of changes in signal per second.
Frequency: Frequency refers the number of periods in one second here the term period denotes the amount of time a signal needs to complete one cycle it means frequency is cycles per second. It is measured in Hertz or HZ.
Bandwidth : Bandwidth is speed of bits transmission in a channel means how many bits can be transferred in one second. It also represents the channel capacity.
