Frequent disconnection caused by ADSL telephone line Interference (1)

The network is often dropped, and many technical staff think it is caused by unstable vrouters. This is not the case. Sometimes, improper setup of a small part of the Network may affect the network stability.

The following is an enterprise network administrator who explains his experience in solving network disconnection:

A small network company in Guangzhou uses an ALPHA G3 router for commercial Internet access. The company proposed that during use, all computers in the LAN would lose 5 or 6 times per hour. As a result, they could not access the Internet normally. After receiving a call, I arrived at the site with great technical support.

Network Structure Analysis

First, I learned about the company's network. They paid the annual fee for the 2 m broadband ADSL package applied for by China Telecom. The ADSL used is provided by China Telecom when applying for broadband. The company's telephone lines and network segments are shown in the figure). The company's connection method is: the requested 2 m broadband line is connected to the WAN port of the router after ADSL, the four LAN ports at the bottom of the router are connected to four Taiwanese computers. After careful observation, there is no error in this method.

Figure 1

Eliminate network instability

The customer said that the line would be dropped four or five times per hour on average, that is, there would be a Line Disconnection every 10 minutes, for this reason. I first use a computer in the LAN to enter the WEB interface of the router. It uses PPPOE serial numbers to access the Internet, and the vro can also dynamically obtain the DNS and IP addresses of China Telecom, and other basic configurations in the vro are normal. In order to further clarify the cause of the disconnection, I use the PING function: a computer can continuously PING the DNS and router gateway of China Telecom. As shown in figure 2 ).

Figure 2

Normally, the average response time obtained by pinging the DNS of China Telecom should be around 17.5ms, and the response from PING the other end of the router should be less than or equal to 1 ms. If the PING Telecom response time is short, it indicates that the ISP's city control switch has a stronger CPU processing capability. On the contrary, the response time is too long, for example, 80 ~ Ms indicates that the ISP's city-controlled switch CPU processing speed is not strong and most of the users are allocated, or the distance between the destination and the ISP's carrier is too long.