What is Network Protocol, and How Does It Work?
A network protocol is an established set of rules that determine how data is transmitted between different devices in the same network.
The OSI
model: How network protocols work
To understand the nuances of
network protocols, it's imperative to know about the Open Systems
Interconnection (OSI) model first. Considered the primary architectural model
for internet working communications, the majority of network protocols used
today are structurally based on the OSI model.
7. Application Layer
The application layer is used by end-user software such as web
browsers and email clients. It provides protocols that allow software to send
and receive information and present meaningful data to users. A few examples of
application layer protocols are the HTTP, File Transfer
Protocol (FTP), Post Office Protocol (POP), Simple Mail Transfer Protocol
(SMTP), and Domain Name System (DNS).
6.
Presentation Layer
The presentation layer prepares data for the application layer. It
defines how two devices should encode, encrypt, and compress data so it is
received correctly on the other end. The presentation layer takes any data
transmitted by the application layer and prepares it for transmission over the
session layer.
5. Session Layer
The session layer creates
communication channels, called sessions, between devices. It is responsible for
opening sessions, ensuring they remain open and functional while data is being
transferred, and closing them when communication ends. The session layer can
also set checkpoints during a data transfer—if the session is interrupted,
devices can resume data transfer from the last checkpoint.
4. Transport Layer
The transport layer takes
data transferred in the session layer and breaks it into “segments” on the
transmitting end. It is responsible for reassembling the segments on the
receiving end, turning it back into data that can be used by the session layer.
The transport layer carries out flow control, sending data at a rate that
matches the connection speed of the receiving device, and error control,
checking if data was received incorrectly and if not, requesting it again.
3. Network Layer
The network layer has two
main functions. One is breaking up segments into network packets, and
reassembling the packets on the receiving end. The other is routing packets by
discovering the best path across a physical network. The network layer uses
network addresses (typically Internet Protocol addresses) to route packets to a
destination node.
2. Data Link Layer
The data link layer
establishes and terminates a connection between two physically-connected nodes
on a network. It breaks up packets into frames and sends them from source to
destination. This layer is composed of two parts—Logical Link Control (LLC),
which identifies network protocols, performs error checking and synchronizes
frames, and Media Access Control (MAC) which uses MAC addresses to connect
devices and define permissions to transmit and receive data.
1. Physical Layer
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