Why we need both IP and MAC addresses?

Can't routers just forward packets to individual computers by IP addresses alone? This has been bothering me and I would like some explanations please.

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Comments

TechxWizard

Your IP Address can change. Your mac addresses doesn't change. (hardly ever)

DoubleNNs

I'm no Security professional, but I used to spoof MAC addresses for people in college so they could hook their video game systems to the Internet. Freshmen and sophomore year it was only allowed to connect one computer per student. You also had a bandwidth limit. I'd show students how to spoof the MAC addresses so that their laptop and video game systems would share the same MAC, how to switch with your roommate who is home 4/7 days of the week when you hit your bandwidth cap, and/or how to connect a switch/AP and have the system think the switch/AP was your laptop.

Once again, I'm no Security professional, nor am I a high level networking pro, but I know it's pretty easy and quick to spoof MAC addresses. Possibly easier than configuring a static IP address on a client machine.

scaredoftests

and you would get a 'duplicate IP address' warning message..

gespenstern

Theoretical abstract routers in vacuum certainly can. The thing is we live in a real world where everything changes. People die, new get born, protocols are designed with flaws, flaws in design get fixed, etc.

In order to address this changing nature without redesigning EVERYTHING each time someone in the past came up with a bright idea of a protocol stack. There you have several to a certain degree independent layers that carry information on their level of understanding how things work on a network. And if some layer doesn't suit your needs well you can kick it out of stack and replace with a similar layer protocol, that's how whole TCP/IP evolves.

Theoretically if they were gods and knew everything they could have designed a godly all-in-one protocol that addresses every communication need at all times during a lifespan of a Universe. But they were just human beings and their work in some parts eventually became obsolete. Thanks to modular structure obsolete parts could be replaced without breaking everything and rebuilding everything.