Ping Command-Network Fault Diagnosis Assistant

Article No.: 1005-6033 (2006) 18-0230-02
Abstract: A convenient and practical ping command for Network Fault Diagnosis tool is introduced. The working principle, usage method and practical application in Network Fault Elimination are discussed.
Key words: Ping Command; network fault; IP Address
Graph classification: tp393.08 document identification code:
Sichuan Radio and Television University has built a gigabit backbone network and a campus network of 100 MB to the desktop, which provides great convenience for teachers and students to share online resources. However, sometimes users may encounter a situation where they suddenly cannot access the Internet. In this case, using the Ping Command provided by the window system allows users to detect and eliminate the cause of network congestion, to quickly resolve network faults.
1. How the ping command works
The Ping (packet Internet groper) command is an internal command in Windows ME, Windows2000, and Windows XP operating systems. It is the most commonly used Fault Diagnosis and troubleshooting command in network faults. The Ping Command is mainly composed of a group of ICMP (Internet-controlled Message Protocol) response request packets. It is a test tool for TCP/IP protocol, determine whether the local host can exchange (send and receive) data with another host. Currently, Internet users use the TCP/IP communication protocol to access the Internet. ICMP is a sub-Protocol of the TCP/IP protocol cluster. It is located at the IP layer of the network structure and provides the ability to transmit error packets, control packets, and Query Packets. The ping command uses the request message and Request Response Message from many ICMP packets to test whether the sink is reachable. This command sends a send-back request data packet to the target host (address), requesting the target host to receive a response after receiving the request to determine whether the host is connected to the target host (address, the response time of the network and the loss rate of data packets during transmission are used to determine whether the TCP/IP protocol parameters are set correctly and whether the network runs normally.
2. Ping Command Format
The Ping Command is generally in the following format: ping [-T] [-A] [-N count] [-l size] [-F] [-I TTL] [-V TOS] [-r count] [-s count] [[-J host-list] | [-K host-list] [-W timeout] destination-list Ping [parameter] (target address)
The target address is the IP address or domain name of the tested computer. The combination of parameters in the ping command allows us to manage the network more flexibly and conveniently. The functions of common parameters in the ping command are shown in table 1.
3. Ping command usage
Ping Command is very convenient to use, in the Windows System "start" menu "run", Options dialog box and MS-DOS mode can be entered in the format of ping command, wait for the delivery information to understand the network working conditions, so as to detect and maintain network faults or analyze network performance. Take Baidu search site address www.baidu.com as an example, In the MS-DOS under the C directory down to use this command to see what the results are.
C: \ Ping Baidu.com
If the computer can communicate with the website address after the Ping, the test is successful as follows:
"Pinging Baidu.com [220.181.18.114] with 32 bytes of data:
Reply from 220.181.18.114: bytes = 32 time = 54 ms ttl = 51
Reply from 220.181.18.114: bytes = 32 time = 54 ms ttl = 51
Reply from 220.181.18.114: bytes = 32 time = 54 ms ttl = 51
Reply from 220.181.18.114: bytes = 32 time = 54 ms ttl = 51
Ping statistics for 220.181.18.114,
Packets: Sent = 4, stored ED = 4, lost = 0 (0% loss)
Approximate round trip times in Milli-seconds:
Min imum = 54 MS, maximum = 53 MS, average = 53 Ms"
The first statement shows that the IP address of www.baidu.com is 220.181.18.114, and bytes = 32 indicates that the size of the Test message is 32 bytes. In the displayed information, there are four statements including reply, which indicate four responses after four data packets are sent to the IP address 202.108.22.33, meaning no packet loss. Time = 54 ms indicates that the time used for a round-trip between the original host and the target host is 54 MS, the shorter the time, the more smooth the line between the host. The change in the return time of each packet is called the jitter (jitter). If the change is large, it indicates that the network connection is poor and the work is unstable. TTL = 51 indicates the lifetime of the currently used data packets in the network is 51 Ms. "Ping statistics for 220.181.18.114" shows the result analysis. "packet: Sent = 4, sorted ED = 4, lost = 0 (0% loss)" indicates four data packets are sent, four data packets are received, so there is no loss in the process. The loss rate of a natural packet is 0%. "Minimum = 53 MS, maximum = 54 MS, average = 53 Ms" indicates that the four datagram texts return the fastest speed of 53 MS, the slowest is 54 MS, the average speed is 53 Ms.
If the computer cannot communicate with the domain name (or IP address) after Ping, the ping failure information is displayed, and "request time out" or "unknow host... Or "destination host unreachable. Different error messages mean that the network cannot communicate because of errors in different links on the network.
4. Ping Command Application
The packet sent by ping command is very small, and the transmission speed on the network is very fast. It can quickly detect whether the site you want to access is accessible. If the ping operation fails, the fault may be caused by network cable failure, incorrect network adapter configuration, or unavailable IP address. If the ping operation succeeds, the network is still unavailable, the problem may be due to the software configuration of the network system. Therefore, in order to quickly diagnose the process of network faults, there is a basic sequence of using the ping command for network fault detection.
4.1 check the TCP/IP protocol configuration of the Local Machine
Run the "Ping 127.0.0.1" command to perform a loop test on the local machine to verify whether the local TCP/IP protocol is correctly installed. When executing this command, the test data packet is transmitted only on the local computer and not sent to the network. If the test is successful, the TCP/IP protocol is successfully installed. Otherwise, the installation or operation of TCP/IP is faulty. Perform fault analysis according to the following steps: 1. Check whether the computer has installed the TCP/IP protocol. 2, whether the NIC of the computer is correctly installed (including checking whether the NIC or modem is in good contact with the host); 3. Whether the TCP/IP protocol of the computer is effectively bound to the NIC; 4, if it is an NT Network, check whether the network function of the Windows NT Server is enabled.
If the problem persists after performing the preceding steps, delete and reinstall the TCP/IP protocol.
4.2 check the configuration of the local IP Address
If you do not know the IP address of the local machine, you can find the IP address of the local machine in the MS-DOS with the ipconfig (winipcfg in Windows) command. Enter the ipconfig command at the command prompt and the IP address, subnet mask (subnet mask), and gateway (Default Gateway) of the local machine on the network will be returned ). Take the address 192.168.10.16 as an example. Run the "Ping 192.168.10.16" command for testing. This command is sent to the IP address configured on the local computer. The computer should always respond to this command. If not, it indicates that the local address configuration is faulty. You can perform fault analysis according to the following steps:
(1) check whether the IP address of the machine has been used by other users. To check whether the network has a duplicate IP address with the local machine, use the ping command (for example, Ping 192.168.10.16) when the network is connected. If no response is received, use this command after disconnecting the local machine from the network. If the response is correct, you can preliminarily determine that there are duplicate IP addresses in the network.
(2) check whether the I/O address, IRQ value, and DMA value of the NIC conflict with other devices. When the IP address of the local machine is successfully pinged, it only indicates that the IP Address Configuration of the local machine is correct, but it does not indicate that the NIC configuration is completely correct. For example, although the computer name of the local machine can be seen in the "Network Neighbor" of the local machine, but it cannot be connected to other users, the problem often lies in the network card.
4.3 check whether the network line is smooth
Ping the IP address of a computer in the same CIDR block. If the "request time out" prompt appears, it indicates that there is a problem with the network route. You should troubleshoot network devices and communication media in segments one by one, including cables, NICS, and loose crystal headers.
4.4 check DNS configurations
If the IP address can be used in the ping command and the domain name (DNS) corresponding to the IP address cannot receive the correct response, it indicates that the Domain Name of the host cannot be converted to the corresponding IP address of the host. Then, it can be preliminarily determined that the DNS server is faulty or the domain name is incorrect.
4.5 check gateway configurations
A gateway is the IP address of a router device that connects to other networks. If there is no problem with the communication with the host on the same subnet, but the communication with the host outside the subnet still cannot be established, the problem may be caused by the configuration method of the router and its address. If you want to communicate with a host outside the subnet, a router address must match the default gateway address of the client on the local subnet. Generally, there are other ports on the router, different ports are configured with different addresses and can be connected to different subnets accordingly. Ping the default gateway to check the subnet Address Configuration and router Problems of the client. If the ping to the default gateway fails, perform the following Fault Analysis: 1. Check whether the subnet mask of the local machine is correctly configured; 2. Check whether the default gateway address of the Local Machine matches the vro address; third, check whether the subnet of the local machine is connected to the router smoothly and whether the router is faulty.
When a network failure occurs, as long as the user finds the Cause according to the above detection sequence, the problem will be quickly located.
5 conclusion
The Ping Command is the most commonly used command in Network Fault Diagnosis. Any computer that uses the TCP/IP protocol can use the ping command to test the network connectivity of the computer. If the ping operation is correct, faults in the input/output lines, cables, and routers of the network access layer, network adapter, and modem can be basically ruled out. Through the above introduction to the working principle, usage, and analysis and application of the ping command in actual network faults, we can see that the ping command is very powerful. As long as we continue to practice the function and parameter usage of the command, pay attention to the normal running status of the network, and analyze the fault phenomenon calmly when the network fails, the command is used to obtain the diagnostic information, determine the network fault point, and eliminate the fault.
References
[1] Zhou tomorrow, Wang wenyong. TCP/IP network principles and technology [M]. Beijing: Tsinghua University Press, 2002: 81-85.
[2] Ma Xinwen. Use the ping command to troubleshoot network faults [J]. Computer Learning, 2005 (3): 17.
[3] Chen wangfeng. Application of fault detection tool Ping in network management [J]. Journal of Yangzhou Vocational University, 2002 (4): 21.
(Intern Editor: Li Min)
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Introduction to the first author: Zhang Jing, female, born in September 1972, graduated from the University of Electronic Science and Technology in 1996, engineer, Information Center, Sichuan Radio and Television University, No. 3, third-section west, yihuan Road, Chengdu 610073, Sichuan province.
Ping Command -- an assistant of Network Fault diagnosiszhang jingabstract: This paper introduces the ping command, a convenient and practical tool for network fault diagnosis, and discusses on its working principle and usage and its practical application in removing network faults.
Key words: Ping Command; network fault; IP Address