Low-level protocols and High-level protocols Explained

This tutorial explains the differences between low-level protocols and high-level protocols. Learn what the lower-level and higher-level protocols are.

A protocol is a set of rules that control a specific part of data communication. Data communication is the exchange of data between computers on networks. It involves several steps. Let's take a simple example to understand these steps.

Suppose two PCs are connected to a network. PC1 wants to retrieve a file stored on PC2. To do so, PC1 has to locate the PC2 on the network, establish a connection with PC2 and request the file. If PC2 accepts the request and provides the file, then receive the file, verify the received file, and terminate the connection.

The whole process is controlled through a series of protocols. Some protocols handle the logical part of the process, while the remaining protocols handle the physical part. The protocols that control the logical part are known as the high-level protocols, while the protocols that control the physical part are known as the low-level protocols.

On PC1, high-level protocols generate a request message and give it to the low-level protocols. Low-level protocols attach the destination computer's address to the message and convert it into electronic signals and load them to the network's media.

All computers connected to the network's media see the signals, but all computers except the destination computer (PC2) will ignore the signals. To determine whether the signals are intended for them, lower-level protocols on every computer convert the signals into the message and check the destination address. If a computer sees its address in the destination address, it transfers the message to the higher-level protocols for further processing. If it sees another computer's address in the destination address, it discards the message.

On the destination computer (PC2), higher-level protocols process the request message. They check whether PC1 is allowed to access the requested file. If PC1 is allowed, they prepare the requested file for transmission and transfer it to lower-level protocols. Lower-level protocols attach the PC1's address to the file, convert it into electronic signals, and load them to the network's media.

Lower-level protocols on PC1 receive the signals, check the destination address, and transfer the file to higher-level protocols. Higher-level protocols perform various checks to verify that the file is received from the correct destination. If the file passes all checks, they transfer it to the corresponding application.


Lower-level protocols

low-level protocols control the physical part of data communication. There are many lower-level protocols. Each protocol uses a different method for computers to access the network. Three main lower-level protocols are Token Ring, ARCNET, and Ethernet.

Token ring

Token ring passes data packets into a circle from PC to PC until they reach their intended destination. It was a popular method in the earlier time of computer networking. Modern computer networks do not use this method.

ARCNET (Attached Resource Computer Network)

This protocol was used in the 1980s for office automation tasks. It is also an outdated protocol.


It is the most popular and mainly used lower-level protocol in modern computer networks. It defines the standards, rules, and mechanisms for wired connections within a network.

Higher-level protocols

High-level protocols control the logical part of data communication. They provide the following functionalities.

  • Initiate, establish, and terminate data connections with the destination devices
  • Control, authenticate, and manage data transmission
  • Provide logical addressing
  • Performing error checks and corrections

Over the years, many higher-level protocols were developed and used on computer networks. Some important higher-level protocols are AppleTalk, IPX/SPX, NetBEUI, and TCP/IP.

Protocol Description
AppleTalk Apple developed it for its computer networks. It is a proprietary protocol. It works only on Apple computers. It does not work on other computers.
IPX/SPX Novell developed it for its computer networks. It is also a proprietary protocol. It works only on NetWare networks. It does not work on another network.
NetBEUI This protocol was developed by Microsoft for its computer networks. It is also a proprietary protocol. It works only on Windows computers. It does not work on other computers.
TCP/IP This is a group of many protocols. It was mainly developed for the Internet. Currently, all companies use this suite as the default protocol suite for data communication.

AppleTalk, IPX/SPX, and NetBEUI are no longer used in modern computer networks. to support TCP/IP, they have been deprecated by their developer companies. Modern computer networks use only the TCP/IP protocol suite. It includes both higher-level and lower-level protocols.

To learn more about the TCP/IP protocol suite, you can check the following tutorial.

TCP/IP Reference Model Explained

Differences between higher-level protocols and lower-level protocols

High-level protocols Low-level protocols
Control the software part of the data communication Control the physical part of the data communication
Generate and process request messages Work on the network adapter
Authenticate request messages and provides the requested files and services Provide hardware addressing
Break large data files into smaller data pieces so they can fit into the attached media Attach hardware address to every message and data piece before converting it into electronic signals
Join data pieces back into data files before transferring them to applications Load electronic signals to the attached media
Provide and attach software address to every data piece Read electronic signals from the attached media. If signals are intended for the host computer, convert them into data pieces and transfer them to high-level protocols

That's all for this tutorial. In this tutorial, we learned about low-level protocols and high-level protocols.

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