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I am currently learning about networking. I am going through the TCP IP and OSI model and try to pick apart what protocol belongs to which layer. I am a bit confused over Media Access Control. Does it just refer to the hardware id of the network card or is it the name of the protocol responsible for it? I tried to find any RFCs for MAC on IETF to provide some definitions for me, but I couldn't find anything.

TheNextman
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bitcasual
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2 Answers2

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"MAC" stands for media access control - it's a sublayer of the data link layer (L2) in the OSI model.

One of the most popular protocols in this layer is Ethernet which covers the physical layer and the data link layer. You can find all about Ethernet at IEEE 802.3 (requires registration but is free).

Another extremely popular L1/L2 protocol stack is WiFi (IEEE 802.11) but that's a lot more complicated and hard to start with.

Zac67
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  • Aha thanks. That makes sense. I always assumed Ethernet just referred to the cable itself. :) Makes much more sense that it being a protocol – bitcasual Mar 29 '18 at 12:55
  • @bitcasual, don't make the mistake of equating ethernet and cabling. Ethernet runs on a variety of media, including different categories of UTP, S/FTP, and fiber optic cabling. The various cables can also be used for many different things, such as POTS, audio, token ring, etc. – Ron Maupin Mar 29 '18 at 13:25
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No, the MAC is not a protocol in that you won't find any 'MAC spec' that you can implement. MACs are typically embedded in hardware devices and expose functionality to send and receive frames to the media that they're controlling.

How they expose that functionality is up to the manufacturer of the MAC. They don't follow any standard protocol. You might find simple SPI interfaces, register-based access, DMA transfer or others.

Andy Brown
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  • Don't confuse MAC with MAC address. The IEEE defines MAC (Media Access Control) as a function for its LAN protocols. MAC uses MAC addresses to perform this function. – Ron Maupin Mar 28 '18 at 14:59
  • @Ron Maupin No confusion here. I was trying to keep it simple without explaining the internals of an ethernet MAC (which can be googled). Thanks for pointing out the distinction though. – Andy Brown Mar 28 '18 at 15:03
  • But you will find specifications for MAC in the IEEE standards. You claim that there isn't any. Part of MAC is handled in the OSI layer-2 of the software. – Ron Maupin Mar 28 '18 at 15:05
  • The OP asked if it was a protocol, not a standard. It isn't a protocol. – Andy Brown Mar 28 '18 at 15:07
  • No, it's not a protocol, but your claim, "_you won't find any 'MAC spec' that you can implement._" is incorrect. You will find the specifications from the IEEE, and they are implemented all the time. It's not just a hardware thing. You are free to write your own drivers for any hardware, and the drivers implementing MAC are standardized per OS. – Ron Maupin Mar 28 '18 at 15:14