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We know MAC address is unique in each devices.So why can't we just send/receive data using MAC address only?

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  • Fundamentally, MAC addressees are used for hop to hop delivery and IP addresses are used for end to end delivery. Both of these roles are crucial for moving a packet through a network.
    – Eddie
    Jun 19, 2016 at 19:44
  • I didn't know that.And the site is useful to understand better.Thanks...
    – Tanvir Rahman
    Jun 19, 2016 at 19:58
  • I would point out that for IPv6, if the host uses EUI-64 addressing, you can actually communicate just knowing their MAC by translating their MAC into an EUI-64 address.
    – Elliot Gorokhovsky
    Dec 7, 2016 at 16:36

2 Answers 2

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MAC is Media Access Control which provides physical connectivity only. IP Address provides Host or Network interface Identification and Location addressing.

For your second question, Let we have two connections, one is for Local connection and other is for internet or virtual machines are running in the system. what happen the IP of both connection will be different but the physical address of machine same. In this case what will you do? In this case IP address defines the address where the system will communicate.

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    Can you please elaborate your first paragraph? Why couldn't MAC addresses be used for network interface addressing? Also, your second paragraph is not clear. How can one connection be "for internet"? Also, @Tanvir Rahman is imagining that we use only MAC addresses, but your hypothetical situation still involves IP addresses.
    – Cameron Hudson
    Feb 10, 2020 at 3:21
  • The other answer is actually way better than this accepted one. I know what MAC is used for, question is, what is the crucial quality, that MAC is missing and disqualifies it from being used as the Internet address? Main reason is, IP address encodes a tree structure which helps routing, but MAC is random, doesn’t encode such structure.
    – hackape
    Apr 2, 2021 at 12:17
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The reason for that is the routing. If you have an IP, for example 104.103.84.161 for the www.microsoft.com, every router on the Internet knows, where to send packets to this IP address. They are organized into a tree-like structure in the Internet, where the IP networks of the organizations have a global registry.

In the case of the MAC addresses, there is no such thing. From a MAC address you can only see which company manufactured the chip, but no more.

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MAC addresses are normally fixed in the NIC firmware, while IP addresses can be freely set everywhere.

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There is also a deeper reason: in the cases of the NIC, there is no guarantee that you want to make IP traffic on them, it is only a quasi-common standard. Earlier existed different protocols (for example, IPX, or the microsoft win2000 servers also had one) which didn't use IP, but another protocol over the NIC cards.

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IP is the standard of the Internet, while the MAC is the standard of the Ethernet. It is not obligatory to use IP from Ethernet, for example in the ancient times there were ARCNET cards which used a quite different protocol (as I know, their "MAC" were much shorter, too).

Or there are VPN protocols which also traffic only IP packets without an Ethernet frame.

So, IP is the common of the Internet, and you can connect into it with everything. Most people connects with Ethernet packets but it is not needed.

Btw, having an "Internet" which uses MAC addresses instead of IP, would be possible, although it would require to develop the complex protocols and shared databases on every protocol layer to use them. They are developed for IP in the times where the Ethernet didn't even existed. So, the final answer to your question is the social inertia.

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    IP actually stands for Internet Protocol, so it was developed for creating internets, including the Internet. IP and ethernet were develop independently, at approximately the same time, for two different reasons.
    – Ron Maupin ♦
    Jun 20, 2016 at 13:31
  • Well explained..
    – West
    Jan 2, 2022 at 15:27
  • 1 & 2 seem to be reasons against your argument. MAC addresses are assigned to the NIC - perfect! That means we know exactly who is who, and those numbers are unique! Who does 1.2.3.4 belong to? As you say, could be anyone! That address can be re-assigned at will! But we know exactly what specific device has such and such MAC address. That seems much better for networking.
    – Mike B
    Sep 6, 2022 at 20:50
  • @mblakesley Knowing who is who does not mean that you also know the route to it anywhere on the world. You would need to develop the required protocols for that. I think it would be possible and maybe it could even lead to a better internet, but it was not done. Note, nothing obliges us to use ethernet below IP, i.e. it is quite possible, and sometimes happens, that no physical network card, or a hardware without a mac address, exists behind an IP.
    – peterh
    Sep 7, 2022 at 11:38

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