Understanding the Relationship Between MAC Layer and Link Layer in Networking

The terms MAC layer and Link Layer (Data Link Layer) are related, but they are not exactly the same thing.

OSI Model Perspective

In the OSI 7-layer model:

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Layer 7  Application
Layer 6  Presentation
Layer 5  Session
Layer 4  Transport
Layer 3  Network (IP)
Layer 2  Data Link
Layer 1  Physical

The Data Link Layer (Layer 2) is often divided into two sublayers:

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Data Link Layer
├── LLC (Logical Link Control)
└── MAC (Media Access Control)

So:

Link Layer = Data Link Layer = Layer 2
MAC Layer = a sublayer of Layer 2

Strictly speaking, MAC is only part of the Link Layer.

Why people often say "MAC layer" when they mean "Link Layer"?

In modern networks, especially Ethernet and Wi-Fi:

Ethernet

The LLC sublayer is almost invisible today.

The functions developers usually care about are:

MAC address
Frame format
CRC/FCS
Medium access

All these belong to MAC.

As a result, engineers often use:

"MAC layer"

instead of

"Data Link layer"

because almost all Layer-2 implementation resides in MAC.

Wi-Fi Example

Looking at the page you currently have open about Wi-Fi MAC processes, the operations are:

Scanning
Authentication
Association
RTS/CTS
CSMA/CA
ACK
Retransmission
Frame exchange

These are all MAC-layer functions.

For Wi-Fi, Layer 2 is almost synonymous with the MAC protocol because:

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802.11 Layer 2
├── LLC (very thin)
└── MAC (very large and complex)

The MAC layer does most of the work.

Therefore, Wi-Fi engineers often say:

"The link layer handles retransmissions"

"The MAC layer handles retransmissions"

and both effectively mean the same thing.

What does MAC actually do?

MAC = Media Access Control

Its responsibilities include:

Function	Example
MAC addressing	48-bit MAC Address
Frame encapsulation	Ethernet Frame, 802.11 Frame
Medium access control	CSMA/CD, CSMA/CA
Error detection	CRC/FCS
ACK and retransmission	Wi-Fi ACK
Association/authentication	Wi-Fi STA ↔ AP
Power saving	Wi-Fi PS mode

Relationship with Physical Layer

For Wi-Fi:

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+-----------------------------+
| IP/TCP/UDP                  |
+-----------------------------+
| Wi-Fi MAC                   |
+-----------------------------+
| Wi-Fi PHY                   |
+-----------------------------+
| Radio (2.4G/5G)             |
+-----------------------------+

PHY handles:

Modulation (OFDM)
Channel coding
RF transmission

MAC handles:

Who can transmit
When to transmit
Retransmission
Acknowledgment
Association

That's why when discussing CSMA/CA , RTS/CTS , authentication , or association , you're really discussing the MAC layer , which is the major functional part of the link layer.

Simple takeaway

Think of it this way:

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Link Layer (Layer 2)
    ↓
    ├── LLC  (small)
    └── MAC  (large)

So:

Technically: MAC is a sublayer of the Link Layer.
Practically: In Ethernet and especially Wi-Fi, the MAC sublayer contains nearly all Layer-2 intelligence, so engineers often use "MAC layer" and "Link Layer" interchangeably.