<TCP/IP> Remember about IP address and Mac Physical Address

Yes, from the first computer network class on March 6, I still have my own doubts about the knowledge points in this book for the first time today. Well, it seems like a good idea to read a book before, um, well, maybe a few more chapters will tell you what it's talking about.

But today has been self-taught to the network layer, this chapter mainly introduces the IP address and physical address, Mac, and the principle of routing protocol, see the ARP cache working principle can not help but feel this way and Ethernet switch is still a bit like.

The problem is that the ARP protocol is to convert IP to physical address, since there is already a physical address why should superfluous use IP address?

Know the reason why.

IP address, everyone image called house number, like map location to show their location, and Mac physical address like a human fingerprint, in the world unique existence. In the real world, if you want to be in contact with others (directly a little), but do not know where he is, you have a fingerprint is meaningless, then you need his location, go directly to the door, and then rely on the fingerprint information alone to identify the person.

I looked at the other big God's answer, some think, IP and Mac exists because the Internet is built on the basis of Ethernet, as a third layer of network layer, need to have a second layer of data link layer support, so the "conflict" is more historical reasons. Some feel that IP can be replaced, not like the NIC Bad lost Mac can not be online, for a network card to continue High,mac is the same, change a place to change a ip,mac can continue high ... There is the IP address can share the router storage Mac Physical address of the pressure, increase processing efficiency ... It makes sense to ask the teacher again when the class is over.

2018-03-26

　　

<TCP/IP> Remember about IP address and Mac Physical Address