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This article will explain in detail what is the role of the ping command, and the content of the article is of high quality, so the editor will share it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

To put it simply, "ping" is a command used to detect whether it is reachable between the local machine and another host in the network. If the ping between the two hosts is not connected, it means that the two hosts cannot establish a connection. Ping is an important means to locate the disconnection of the network.

The ping command works based on the ICMP protocol, and the full name of "ICMP" is Internet Control message Protocol (Internet Control Message Protocol). The ping command sends an ICMP echo request message to the target host and waits for the target host to return an ICMP echo reply. Because the ICMP protocol requires the target host to return the ICMP reply message to the source host after receiving the message, if the source host receives the reply from the target host within a certain period of time, it indicates that the network between the two hosts is reachable.

Give an example to describe how the "ping" command works:

Suppose there are two hosts, host A (192.168.0.1) and host B (192.168.0.2). Now that we want to monitor whether the network between host An and host B is reachable, we enter the command on host A: ping 192.168.0.2

At this point, the ping command will build a request packet for ICMP on host A (the contents of the packet will be described later), and then the ICMP protocol will hand over the packet and information such as the destination IP (192.168.0.2) to the IP layer protocol.

After getting these information, the IP layer protocol constructs an IP packet from the source address (that is, native IP), destination address (that is, destination IP:192.168.0.2), and some other control information.

After the IP packet is built, it is not enough, and the MAC address needs to be added. Therefore, the MAC address corresponding to the target IP needs to be found through the ARP mapping table. When the MAC address and local MAC of the target host are obtained, they are given to the data link layer, assembled into a data frame, and sent out according to the media access rules of Ethernet.

When host B receives this data frame, it will first check whether its destination MAC address is local. If it is received and processed, it will check the data frame, take out the IP packet in the data frame and give it to the local IP layer protocol. Then, after the IP layer protocol has been checked, the ICMP packet will be taken out and handed over to the ICMP protocol. When this step is completed, the ICMP packet will be taken out and handed over to the ICMP protocol. An ICMP reply packet is constructed and sent back to host A.

Within a certain period of time, if host A receives the reply packet, the network between host An and host B is reachable, and if it is not received, the network is unreachable. In addition to monitoring whether it is reachable, the delay time of the packet can be calculated by using the difference between the reply time and the initiation time.

Through the process of ping, we can find that ICMP protocol is the basis of this process and is very important.

What is the role of the ping command to share here, I hope that the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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