The Functions of MAC Sublayer ( IEEE 802.3)

Welcome to the study class conducted by CoreNetworkZ Tech Solutions on the OSI Reference Model. Today, I will teach you the MAC Sublayer in the OSI Reference Model. You will learn about the duties and importance of this sublayer in the OSI.

During the development of IEEE Ethernet, IEEE divided the Data Link layer into two. They are the MAC sublayer and LLC sublayer. MAC sublayer functions are performed in hardware and are the bottom part of the data link layer.

MAC sublayer defines how data is transmitted in an Ethernet environment and defines framing, MAC address, etc.

So, what are the duties of the MAC sublayer in the OSI reference model? Let us check the functions of the MAC sublayer in the details below.

Sijo John asked me in the comments about the functions of the MAC sublayer in the OSI Reference Model. The four functions of this sublayer are:

1. Defines how an Ethernet environment transmits information.

2. MAC Sublayer defines framing

3. This Sublayer defines the working of Ethernet and MAC addressing.

4. CSMA/CD works in the MAC Sublayer.

We know Ethernet has two versions, and we must understand how to differentiate both versions of Ethernet. The primary difference between Ethernet II (developed by DIX) and IEEE 802.2/3 is the frame value.

The frame value of Ethernet II is higher than 1500. The IEEE version of Ethernet uses frames with a value of less than 1500.

So, a network engineer must know the difference between the DIX and IEEE versions of Ethernet while troubleshooting. Only the IEEE version of the Ethernet has two sublayers in the data link layer.

The DIX version of Ethernet (Ethernet 2) does not have sub-layers for the data link layer.

If you learned about the MAC sublayer, I recommend you read about the LLC sublayer. To read more about LLC Sublayer, visit the link below.

Without studying the OSI Reference Model, you cannot start computer networking. To read about the OSI Reference Model and its seven-layered structure, visit the link below.

I have covered the basics of the MAC Sublayer (OSI) in this tutorial. If you are looking for a detailed guide, I recommend you read this Cisco PDF.