Ethernet can be divided into 2 sublayers; MAC and LLC. For WAN protocols like PPP, HDLC and frame relay, it is not discussed in regards to protocol sublayer for media access control. On serial interface, the encapsulation can be chosen from PPP, HDLC, frame relay, etc.

My question is, do WAN protocols like PPP, HDLC and frame relay have their own media access control protocol or do they use the same media access control protocol?

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    – Ron Maupin
    Jan 5, 2021 at 1:33

3 Answers 3


No, PPP, HDLC, FR do not have their own MAC. In the OSI model, MAC is associated with layer 2. PPP, HDLC, FR are on L2 as well. But LLC is associated with L1, the physical layer. MAC is not just a theoretical concept like a sublayer, MAC is a protocol by itself. There are many LLC protocols, but there is only one MAC, with the exception of a VLAN tag field.

Let us have a look at the third and the fourth field of a MAC portion of an Ethernet frame: Destination MAC Address; Source MAC Address. An address is 6 bytes long. In comparison, an HDLC address is 1 byte long. FR and PPP frames reach their destination very differently from MAC or HDLC.

In a nutshell, Ethernet formats network data on both L2 and L1, while PPP, HDLC, FR stay on L2. That is why none of them needs an extra sublayer.


Ethernet can be divided into 2 sublayers; MAC and LLC.

No and no!

802.3 Ethernet is a stack of protocols :

It includes MAC 802.3 which is a level 2 sublayer and a physical layer specific to 802.3 IEEE

The physical layer is divided in : the RS sublayer, and the PHY 802.3 sublayer

Now, you can have non 802.3 Ethernet, for example ETH over FR over SDH. This is another story.


A media access control address (MAC address), also called physical address, is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet and WiFi. Logically, MAC addresses are used in the media access control protocol sublayer of the OSI reference model. you can find more information about a media access control address on the website http://wlan-wifi.com/mac-address

  • You are answering about LAN protocols, but the question is specific to WAN protocols.
    – Ron Maupin
    Mar 13, 2016 at 19:28

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