Welcome to the Computer Science and Technology Study Materials section from CoreNetworkZ EdTech Solutions, a leading mock test and competitive exam preparation platform, for students preparing for SSC, DSSSB, and Kerala PSC examinations. Today, I will explain MAC Sublayer ( IEEE 802.3).
Introduction
Welcome to the study class conducted by CoreNetworkZ EdTech 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.
IEEE 802.3 defines the MAC sublayer.
MAC sublayer defines how data is transmitted in an Ethernet environment and defines framing, MAC address, etc.
MAC Sublayer = Medium Access Control sublayer
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.
Functions of MAC Sublayer in IEEE Ethernet
Sijo John asked me in the comments about the functions of the MAC sublayer in the OSI Reference Model. Sijo is preparing for the Bank IT Officer examination. The four functions of this sublayer are:
Defines how an Ethernet environment transmits information.
MAC Sublayer defines framing
This Sublayer defines the working of Ethernet and MAC addressing.
CSMA/CD works in the MAC Sublayer.
| Function Category | Detailed Responsibility (IEEE 802.3) |
|---|---|
| Data Encapsulation | Assembles data into Frames before transmission and disassembles received frames (Framing). |
| Media Access Control | Governs how devices share the physical medium using CSMA/CD (Carrier Sense Multiple Access with Collision Detection). |
| Physical Addressing | Responsible for adding the MAC Address (Hardware Address) of the source and destination to the frame header. |
| Error Detection | Appends a Frame Check Sequence (FCS) using Cyclic Redundancy Check (CRC) to ensure data integrity during transit. |
| Interface with Physical Layer | Communicates directly with the Physical Layer (Layer 1) to transmit bits over the copper or fiber media. |
How does This Study Material help PSC, SSC, and DSSSB Aspirants?
SSC, DSSSB, and Kerala PSC conduct examinations for various IT posts.
Understanding MAC Sublayer ( IEEE 802.3) is essential for candidates appearing for the DSSSB PGT/TGT Computer Science, Kerala PSC Degree Level Exam, SSC Scientific Assistant (CS), VSSC Technical Assistant, and System Analyst posts. These networking fundamentals are core parts of the Computer Science syllabus.
Kerala PSC Degree Level examinations have a Computer Science section where students can expect questions that require them to explain the functions of MAC Sublayer ( IEEE 802.3). You can check the Kerala PSC Degree Level Common Prelims Syllabus under the Computer Science section. I recommend you download the syllabus using this official link.
Reference: https://www.keralapsc.gov.in/sites/default/files/2021-02/syllubus.pdf
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How to Differentiate Ethernet II and MAC Sublayer Frames?
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.
We use DIX and IEEE versions of Ethernet today.
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.
Reference
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.
- https://www.keralapsc.gov.in/sites/default/files/2021-02/syllubus.pdf
- https://www.cisco.com/c/en/us/td/docs/net_mgmt/prime/network/3-8/reference/guide/ethrnt.html
Author: Alex George
Alex George is the Chief Editor and founder of CoreNetworkZ EdTech Solutions. He is a software engineer and has 20 years of experience in the EdTech niche.
He graduated with a B.Tech in Computer Science & Engineering from CUSAT and worked with three leading IT companies before starting CoreNetworkZ EdTech Solutions.
He possesses sound knowledge of SOHO Network Engineering and has completed various IT certifications, including CCNA, RHCE, and CEH.
He developed and published more than twenty professional custom themes for Blogger and is an expert in software app development.
You can contact him at alex.george@corenetworkz.com.
Hi Alex,
ReplyDeleteIs MAC layer an independent layer?
It is a sublayer, Anagha.
DeleteCan you write more about the operations done in the MAC sublayer?
ReplyDeleteSure, I have added them.
DeleteHello Sir,
ReplyDeleteI am preparing for the upcoming CCNA examination. Is MAC Sub Layer an important topic to study?
Yes Vishnu. I recommend you study this topic well.
Delete