Physical Link Layer and Data Link Layer of OSI (Open System Interconnection) Model

Physical Layer:-

          The Physical Layer is responsible for sending bits from one computer to another computer. That is ,
it may convert the sequence of bits into electric signals, light signals, or electromagnetic signals, depending on whether the two nodes are on a cable circuit, fiber-optic circuit, or microwave circuit, respectively.

In addition, the physical layer protocols also deal with the mechanical details, such as the size and shape of the connecting plugs, the number of pins in the plugs, and the function of each pin.

Functions of the physical layer are following:-
1. This layer is responsible for sending bits from source computers to destination computer.
2. Bit transmission encoding
3. Transmission rate (i.e. the number of bits transmitted per second)
4. Line configuration
5. Transmission Mode
6. Topology
7. Multiplexing

Data Link Layer :-

Layer 2 of the OSI model provides the following functions: 

• Allows a device to access the network to send and receive messages
• Offers a physical address so a device’s data can be sent on the network
• Works with a device’s networking software when sending and receiving messages
• Provides error-detection capability 

Common networking components that function at layer 2 include: 

• Network interface cards
• Ethernet and Token Ring switches
• Bridges NICs have a layer 2 or MAC address. 

A switch uses this address to filter and forward traffic, helping relieve congestion and collisions on a network segment.

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