I’m aware that the mac address is part of the data link layer, but why can’t I just use my MAC address as IP address, too?
Why do I need both addresses?
In: 14
IP addresses are used when communicating in an IP network. (Duh.)
MAC addresses are used when communicating over an ethernet (or ethernet based) network.
It is perfectly possible to communicate over IP, where one (or both) of the hosts are not connected to an ethernetbase network and therefore also don’t have a MAC address.
Ex: Your mobile device that uses IP over a cellular network, doesn’t have a MAC address on its cellular interface.
If you want to talk over IP to a device on a local network, the MAC address is required and there is a translation protocol (ARP) to discover the local MAC address based on the IP address.
A big difference between IP and MAC addresses is that IP is a routing based protocol, you can address devices outside of your own local network.
MAC addresses are only used locally, you can only reach things that are in your own network. (If you connect to an IP address outside of your local network, on ethernet it connects to the MAC address of your local router.)
In more advanced settings you can have a single IP address being used by multipe devices (and MAC addresses) to provide redundancy/clustering and other fun things.
As there is not always a 1-to-1 relationship between IP and MAC, you can’t really skip it and need both.
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