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What is your answer to "What is Ethernet?"

January 14, 2025 , , ,

 

What is your answer or explanation if someone asks, “What is Ethernet?” Sometimes new learner don’t get the precise answer to this question. Let’s try to learn what Ethernet is here in this small article.

Ethernet is the group of network technologies that are used at layer 1 and layer 2 of the OSI layer. Ethernet at layer 2 provides the physical addressing to the Network Interface Cards in a networking device. Yes you are right this physical address is called the MAC address.

MAC Address is a 6-byte or 48-bits long address that is written in hexadecimal format. If you notice your MAC address you can see that each byte has two hexadecimal characters separated by either colon or hyphen character.

Let’s see how my computer's MAC Address looks like. You can get it from the command prompt using the “ipconfig /all” command and find the "Ethernet adapter" section:

Figure 1: My Computer MAC Address

The physical address in the output is your computer's MAC address. Notice each byte is separated with a hyphen (-) character and there are a total 6 bytes and 12 hexadecimal characters.

This MAC address is globally unique address. I mean there is no other computer that has same MAC address globally. You may question how this is possible. It is possible by following the standard rules define by standard bodies.

One of the rule is that the manufacturer should use only the address assigned to it by the standard body. Each manufacturer is assigned a unique address – first 3 bytes in any MAC address (also known as most significant bytes) are the OUI address assigned to manufacturers.

In my case 50-81-40 is the OUI assigned to HP Inc. if you want to verify your system vender using MAC address you can go to https://macvendors.com site. Just paste your MAC address and it will show you the vendor name.

Second part of the MAC address, I mean next 3 bytes after OUI, represent to the NIC serial number. Every NIC serial is the unique value. A manufacturer cannot assign the same serial number to two NICs. This way a MAC address is globally unique address.

Sometimes there are networking software when installed on the systems also get the MAC address. If you see a MAC address starting with x2, x4, xA or xE, it is the private address. It is same as private IP address defined in RFP 1918. Now a days products form popular vendors like Apple, Microsoft can pseudo-randomize their device MAC address for higher privacy. They utilize the private MAC ranges to achieve the same.

Hope you find this small article informative. 

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