Networking Primer – Part 6.1: Data Link Layer, Ethernet and MAC

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In previous posts we’ve covered logical addressing and moving IP packets of data across our network from source to destination. We’re now going to take a further shift towards the bits and bytes details of how that logical addressing and routing relates to the more tangible physical media that is used to transmit the data. This is where the Data Link Layer becomes applicable. “The Data Link Layer” is a bit of a mouthful, so this is often dropped and the OSI stack layer number is substituted, Layer 2. From this point forward I will use “Data Link Layer” and “Layer 2” as interchangeable terms which mean exactly the same thing.

The Data Link Layer breaks down into two sub-layers. Firstly, we have the upper sub-layer, called Logical Link Control (LLC) and beneath it we have the Media Access […]