Physical layer co-ordinates the functions required to transmit a bit stream over a physical medium. It deals with the mechanical and electrical specifications of the interface and transmission medium.
The lowest layer of the OSI reference model is the physical layer. It is responsible for the actual physical connection between the devices. The physical layer contains information in the form of bits. It is responsible for transmitting individual bits from one node to the next.
Functions of physical layer :
- Data Rate –
This layer defines the rate of transmission which is the number of bits per second.
- Interface –
The physical layer defines the transmission interface between devices and transmission medium.
- Representation of Bits –
Data in this layer consist of stream of bits. The bits must be encoded into signals for transmission.It defines the type of encoding i.e.how 0’s and 1’s are changed to signals.
- Line configuration –
This layer connects devices with the medium either it can be point to point configuration or Multipoint configuration.
- Transmission Modes –
Physical layer defines the direction of transmission between two devices such as Simplex, Half duplex, Full duplex.
- Topologies –
Devices must be connected through any topologies either it can be Mesh, Star, Bus And Ring.
Design Issues in Physical Layer :
- The physical layer is basically concerned with transmitting raw bits over a communication channel.
- Mainly the design issues here deal with electrical, mechanical, timing interfaces, and the physical transmission medium, which lies below the physical layer.
- Design issue has to do with making sure that when 1 bit send from one side, it is received 1 bit by other side also not as a 0 bit.
Some questions are here like :
- How many nanoseconds a bit lasts ?
- How many volts should be use to represent a 1 bit and how many for a 0 ?
- How many pins the network connector has and what each pin is used for ?
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- Design Issues in Network Layer
- Design Issues in Presentation Layer
- Design Issues in Data Link Layer
- Design Issues of Distributed System
- Responsibilities and Design issues of MAC Protocol
- Difference between Secure Socket Layer (SSL) and Transport Layer Security (TLS)
- Difference between layer-2 and layer-3 switches
- Physical and Logical Data Independence
- Physical Components of Computer Network
- Difference between Physical and Logical Topology
- Cisco Discovery Protocol (CDP) and Link Layer Discovery Protocol (LLDP) in Data Link Layer
- Wireless Media Access Issues in Internet of Things
- Mapping Virtual Addresses to Physical Addresses
- TCP and UDP in Transport Layer
- Transport Layer responsibilities
- Devices used in each layer of TCP/IP model
- Traceroute in Network Layer
- Protocols in Application Layer
- Supernetting in Network Layer
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