Why does the Internet require an IP address and MAC address?

1 Basic Concepts

An IP address is an Internet protocol address, each Internet package must have an IP address, and each Internet service provider (ISP) must request a set of IP addresses from the organization concerned, and then generally dynamically assign it to its users.

The MAC address is the address on the Ethernet network card with a length of 48 bits. Each Ethernet NIC manufacturer must request a set of MAC addresses from the IEEE organization to write a unique MAC address in the serial EEPROM of the NIC when the network card is produced.

2 Why do I need an IP address and MAC address?

The first case: Broadband users via ADSL dial-up Internet

• The user/host (e.g. host A) does not have an IP address initially;
• Router A (PPPoE Client) may be the Tp-link wireless router, the IP address of each interface is also not;

(1) in the local area network composed of host a/b/c, how does each host communicate before acquiring an IP address? How to determine if a message is sent to itself? (2) in the actual network, there should be more than one PPPoE client connected to the same PPPoE server, thePPPoE server depends on what distinguishes each PPPoE client, how to establish contact with each PPPoE client?
To analyze the above problem, feel the MAC address is necessary, unique.
Second scenario: Router's routing table


As you can see, each row of the routing table contains the destination address, netmask, next-Hop IP address, and so on. It is because of the existence of the network mask that greatly simplifies the routing table.

Imagine that the routing table is based on the MAC address. The MAC address is the address on the Ethernet network card with a length of 48 bits. Each Ethernet NIC manufacturer must request a set of MAC addresses from the IEEE organization to write a unique MAC address in the serial EEPROM of the NIC when the network card is produced.

Then, the MAC address of all network devices in a region is different, and there is no connection. Not like the IP address is regular (IP address is assigned by the ISP, can be considered control), there is no "network mask" possible, each host may need a routing table entry, resulting in the core network router routing table is huge, is unacceptable.

Therefore, the IP address (logical address) is necessary.

3 Summary

This question has actually been thinking for a long time, but I have not made it very clear. In this paper, only two practical applications, IP address and MAC address are required.

Why does the Internet require an IP address and MAC address?