From the course: Networking Foundations: Networking Basics
MAC addresses
From the course: Networking Foundations: Networking Basics
MAC addresses
- With so many different devices that populate our networks, how do we tell one device apart from another device? Well, the answer is addressing. And we're going to consider both physical and logical addressing beginning in this video with physical addressing. Now physical addresses, they're assigned to network devices when they're manufactured. And because of that, we often call those addresses burned in addresses. And the specific physical address that we want to consider is the media access control address, or the MAC address for short. Consider a network interface card, or NIC. When a company manufacturers the card, they assign it a unique MAC address, and no other device in the world should have that same MAC address. The way manufacturers keep from overlapping one another in their assignment of these MAC addresses is each manufacturer has their own unique code. It's called a vendor code, and that makes up the first half of the MAC address. In fact, let's consider the structure of a MAC address. A MAC address is made up of 48 bits. And those 48 bits, they're divided into two different groupings, 24 bits each. The first 24 bits, those are unique to the specific manufacturer or vendor. Those bits are called the OUI, or organizationally unique identifier. The OUI is also commonly referred to as the vendor code. And we're going to see a little bit later that there's a piece of networking gear called a switch that allows us to use those MAC addresses to make forwarding decisions for data as it flows through the network. But for now, I just want you to understand that a MAC address is a 48-bit physical address and the first 24 bits, they identify the manufacturer of that network device.
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