Why are MAC addresses needed?

+49 votes
asked May 25, 2015 in Computers & Electronics by GregorioYaga (230 points)
I’m trying to learn more about computers and the specifics of the internet. It’s something I’ve always been interested in, and there are a lot of good careers involving computers! So far it’s going pretty well, but some of the details really get bogged down. One thing I don’t understand is what purpose MAC addresses serve for. Why are MAC addresses needed?

3 Answers

+29 votes
answered Sep 9, 2015 by RachelleSaye (350 points)
MAC addresses are just one of the basic components of Ethernet networks, but even though they serve a low level function, they are important for the internet’s local network to work. MAC addresses are needed for a device to connect with and communicate with a machine on this local level. They only work on this physical local network level though, often called a LAN. This is different from how an IP address works because they can cover the whole internet. Routers use these to figure out where to direct data, even across several different areas or connections. These don’t really affect your physical connection though, which is where the MAC address takes over. So these two different addresses have to work together to help you access the world of the internet from your personal location.
+7 votes
answered Sep 18, 2015 by CorneliusMar (330 points)
Sometimes wireless devices and wireless connections need MAC addresses to control the access of other devices. All devices have a unique MAC address, so these wireless access points can use this to identify that a known device with the correct password is seeking access. This storage is why your iPhone or computer will automatically connect to internet somewhere that you’ve already entered the password for. It stores this information, and the wireless access point identifies that it’s connected with this device before because of the address.
+6 votes
answered Jul 28, 2015 by TrinaDunford (360 points)
Network switches will access and store a list of MAC addresses that they come in contact with for easy access. So guess why are MAC addresses needed? These addresses are needed so that these switches know where to send what packets and what ports need access to these packets. So in this case they operate a lot like cues for a conductor to see where everything is going and to make sure it gets where it needs to go.
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