LAN test and troubleshooting experience-traditional and classic technology

If you are a network administrator, I believe you will certainly be troubled by network failures as much as the author. The biggest difference between a network and a single machine is the characteristics of the whole body. The problem on a single machine is likely to be mapped to a link in the network, or even destroy all network operations. So when the network, especially the LAN of home and enterprise users, fails, how should we face it and how should we deal with it? Haha, there is a hard way, soft and soft, the solution may involve many aspects, and even there are related hardware testing tools abroad, but the price ...... This article is only widely used in domestic LAN Discuss the network testing tools built in the Windows 98 / NT / 2000 operating system with netizens Zhu Jun.

1. Ping's technique believes that the buddies who have played the Internet will know the command "Ping" well. The Ping command is a detection tool dedicated to TCP / IP protocol integrated in Windows 95/98 / NT. Generally, it is a local or wide area network that uses the TCP / IP protocol. Whether you are a home, office LAN that only manages a few computers internally, or a campus network, an enterprise network, or even the Internet international Internet network, when the client is not When access is normal or there are various unstable situations in the network work, it is recommended that you first try to use the Ping command to confirm and eliminate the problem, and sometimes it will work once.

1. Syntax format of Ping command

Since it is a technique, of course, it is necessary to introduce the specific syntax format of the Ping command to the buddies who do not understand the Ping command: ping destination address [parameter 1] [parameter 2] ...

The destination address refers to the IP address or domain name of the computer under test. The main parameters are:

a: Resolve the host address.

n: data: the number of test packets sent, the default value is 4.

l: value: the size of the sent buffer.

t: Continue to execute the Ping command until the user presses Ctrl + C to terminate.

For other parameters of Ping, you can run Ping or Ping- at the MS-DOS prompt. Command to view.

2. Ping command application skills

When using the Ping tool to check the operation of the TCP / IP protocol on the network server and any client, just ping the IP address of the computer on any other computer in the network. For example, to check whether the TCP / IP protocol on the network file server 192.192.225.225 HPQW is working properly, just type Ping 192.192.225.225 in the "Run" sub-item under the Start menu. If the TCP / IP protocol of HPQW is working properly, the following information will be displayed in DOS screen mode:

Pinging 192.192.225.225 with 32 bytes of data:

Reply from 192.192.225.225:bytes=32 TIme = 1ms TTL = 128

Reply from 192.192.225.225:bytes=32 TIme <1ms TTL = 128

Ping statistice for 192.192.225.225:

Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)

Approximate round trip times in milli-seconds:

Minimum = 0ms, Maximum = 1ms, Average = 0ms

The above returned 4 test data packets, where bytes = 32 means that the size of the data packet sent in the test is 32 bytes, time <10ms means that the time used to travel to and from the opposite host is less than 10 milliseconds, and TTL = 128 means the current test The TTL (Time to Live) value is 128 (the system default).

If there is a problem with the network, the response failure message shown below is returned:

Pinging 192.192.225.225 with 32 bytes of data

Request timed out.

Ping statistice for 192.192.225.225:

Packets: Sent = 4, Received = 0, Lost \ = 4 (100% loss),

Approximate round trip times in milli-seconds

Minimum = 0ms, Maximum = 0ms, Average = 0ms

When this happens, as the network administrator, you must carefully analyze the causes of network failures and possible problematic online nodes. It is recommended to investigate from the following aspects: First, see if the computer being tested has TCP installed / IP protocol; the second is to check whether the network card of the tested computer is installed correctly and is connected; the third is to see if the TCP / IP protocol of the tested computer is effectively bound to the network card (the specific method is by selecting "Start â†’ Settings" â†’ Control Panel â†’ Network â€to check); Fourth, check if the network service function of the Windows NT server has been started (you can findâ€œ Server â€in the dialog box that appears by selectingâ€œ Start â†’ Settings â†’ Control Panel â†’ Services â€ Item, see if the displayed under "Status" is "Started"). If you have not found the crux of the problem through the above four steps, I suggest that you reinstall and set up the TCP / IP protocol. If it is a problem with the TCP / IP protocol, it can definitely be solved completely.

According to the above method, we can also use the Ping command to check the operation of TCP / IP on any client computer. For example, if we want to check the configuration and working status of the TCP / IP protocol on any client "Computer Room 01" on the network, we can directly ping the IP address of the machine on the machine. If a successful message is returned, the IP address configuration is correct. If it fails, you should check the IP address configuration. This can be done by the following steps: first check the entire network, focusing on whether the IP address is being used by other users, and then see if the workstation is correctly connected to the network (in many cases, this will also occur if the user is not logged in to the network) In this case, this is a low-level error). Finally, check the network card's I / 0 address | IRQ value and DMA value, whether these values â€‹â€‹conflict with other devices. The inspection of the last item is very important, and is often overlooked by many users. Even after Ping is successful, this item should be checked. Because after successfully pinging the IP address of the machine, it only shows that there is no problem with the IP address configuration of the machine, but it does not mean that the configuration of the network card is completely correct. At this time, although the computer name of the machine can be seen in the "Network Neighborhood" of the machine, it can not communicate with other users. I don't know where the problem is. In fact, the problem is often on the network card.

In fact, the focus of the above application techniques is still the application of the Ping command in the local area network. In fact, the Ping command is not only widely used in the local area network, but also often used in the Internet to detect the remote connection of the network. Usually, when we encounter the following two situations, we need to use the Ping tool to test the network connectivity. For example, when the webpage of a certain website cannot be accessed, the Ping command can be used for detection. For example, when you cannot access the homepage of CCID.com, you can use the "Ping" command line to test. If you return a message similar to "Pinging ns. Ccidnet.com with 32 bytes of data: ...", the other party's host It has been turned on. On the contrary, it indicates that there may be a fault in a link of the network connection, or the host of the other party is not turned on. In addition, we can also test the network connectivity before sending E-mail. Many Internet users often receive messages such as "Returned mail: User unknown" after sending E-mail, which means that your mail has not been sent to the destination. In order to avoid such incidents from happening again, it is recommended that you develop the habit of pinging the other party's mail server address before sending E-mail. For example, when you send an email, you can first type "ping 188.net" to test, if it returns a message similar to "Bad IP address cniti.com" or "Request times out", it means that the other party's host is not open or the network Not connected. At this time, even if the mail is sent, the other party cannot receive it.

Although the Ping command is simple, it is very effective in practical use. It is believed that flexible use will definitely bring unexpected surprises to your network management career.

2. The technique of Ipconfig / Winipcfg is different from that of Ping. Use Ipconfig and Winipcfg tools to view and modify the configuration of TCP / IP protocol in the network, such as IP address, gateway, and subnet mask. These two tools can be used in Windows 95/98, the function is basically the same, but the character form of Ipconfig jc DOS is displayed, and Winipcfg is displayed with a graphical interface. At the same time, there is only Ipconfig tool running in DOS mode in Windows NT.

1. Ipconfig command syntax format

Ipconfig can be run in the DOS prompt of Windows 95/98 / NT, the command format is:

Ipconfig [/ parameter 1] [/ parameter 2] ......

Two of the most practical parameters are:

all: Displays all details related to the TCP / IP protocol, including the host name, node type, whether IP routing is enabled, the physical address of the network card, and the default gateway.

Batch [Text File Name]: Store the test results in the specified text file name for easy viewing item by item.

Other parameters can be viewed at the DOS prompt by typing the "Ipconfig /?" Command.

Ipconfig should be said to be a weapon for network reconnaissance, especially when DHCP (Dynamic IP Address Configuration Protocol) is set in the user's network, using Ipconfig can let users easily understand the actual configuration of IP addresses. If we run "Ipconfig / all / batch kunpeng.txt" on the 01 client of the computer room, open the kunpeng.txt file, the following content will be displayed, and the configuration of the TCP / IP protocol is displayed in great detail.

Windows 98 IP configuration

Host Name.........: Nts01

DNS Servers.........: 192.192.225.225

Node Type........:

IP Routing Enabled....: No

WINS Prony Enabled......: No

NetBIOS Resolution Uses DNS.: Yes

0 Ethernet adapter:

Description........: Accton EN1207D-TX PCI Fast Ethe

Physical Address.....: 00-00-E8-39-3A-27

DHCP Enabled......: No

IP Address........: 192.192.225.225

Subnet Mask.........: 255.255.255.0

Default Gateway......... .192.192.225.225

Primary WINS Server.....:

Secondary WINS Server....:

Lease Obtained.......:

Lease Exprires........:

2. Application Skills of Winipcfg Command

The function of the Winipcfg tool is basically the same as Ipconfig, but Winipcfg is more convenient in operation, and can be displayed in the 32-bit graphical interface of WINDOWS. When users need to check the configuration of TCP / IP protocol on any machine, they only need to select â€œStart â†’ Runâ€ on Windows 95/98, enter the command â€œwinipcfgâ€ in the dialog box that appears, and the test results will appear. Click the "Details" button, you can view and change the configuration parameters of TCP / IP in the subsequent dialog box. When multiple network cards are installed on a machine, you can find the physical address and each network card. Regarding the binding of the agreement, this is particularly useful to us at certain times. If you want to get more information, you can click the "details" button in the figure, you can see more comprehensive information in the dialog box that appears.

3. The technique of Netstat is similar to the above network detection software. The Netstat command is also a tool that can be run at the DOS prompt of Windows 95/98 / NT. With this tool, you can display statistics and current TCP / IP network connections The situation, users or network managers can get very detailed statistical results. When no special network management software is installed in the network, but it is necessary to have a detailed understanding of the entire network usage, it is time for Netstat to show its talents.

1. The syntax of the Netstat command

Netstat [-parameter 1] [-parameter 2] ......

The main parameters are:

a: Display the information of all ports established with this host.

e: Display the statistical residence of the Ethernet. This parameter is generally used together with the S parameter.

n: Display address and port information in digital format.

s: Display the statistics of each protocol. These protocols mainly include TCP (Transfer Control Protocol, Transmission Control Protocol), UDP (User Datagram Protocol, User Datagram Protocol), and ICMP (Internet Control Messages Protocol). ) And IP (Internet Protocol, Internet Protocol), the first three protocols are generally rarely used, but it is very useful in the analysis of network performance. Other parameters can be viewed at the DOS prompt by typing the "netstat-?" Command. In addition, a tool called Nbtstat is integrated under Windows 95/98 / NT. The function of this tool is basically the same as Netstat. If you need it, you can type "nbtstat-?" To view its main parameters and usage. When using it, if the user wants to count the detailed information in the current LAN, it can be viewed by typing "netstat-es", it is very simple.

There is a saying that "workers want to do the right thing, they must first sharpen their tools", a good network management software may bring endless fun and incomparable ease to your network management career, but more critical is whether you have mastered In addition to one or more of these tools, I hope this article can be helpful to the junior network administrators.

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