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Technical knowledge
Network fault troubleshooting we may encounter in the actual project, after encountering problems, we need a clear solution to the problem, in order to be able to find out the problem quickly and without panic, so let's take a look together.
First, the basic steps of network debugging
Eliminating network failures may soon be the problem for some older engineers who are more experienced and have a keen sense of smell.
But in fact, they are also a little bit of accumulated experience, constantly summarized in order to do so quickly and efficiently.
So for novices, we must not be too anxious, delusive step by step in place, should be implemented step by step to the basis, from the foundation slowly accumulated.
First of all, we must understand the five steps of network fault-shooting:
(1) See the symptoms first.
(2) List as many causes as possible.
(3) Then the investigation was carried out for each reason.
(4) Find out the reason.
(5) Solving problems.
The second step is critical, because the more possible reasons are found, the greater the success rate of error removal.
2. Error removal cases:
Sequential process is particularly important. It reflects a person's logical thinking. Here is a simple example to familiarize yourself with the specific steps.
First, the basic steps of network debugging
Eliminating network failures may soon be the problem for some older engineers who are more experienced and have a keen sense of smell.
But in fact, they are also a little bit of accumulated experience, constantly summarized in order to do so quickly and efficiently.
So for novices, we must not be too anxious, delusive step by step in place, should be implemented step by step to the basis, from the foundation slowly accumulated.
First of all, we must understand the five steps of network fault-shooting:
(1) See the symptoms first.
(2) List as many causes as possible.
(3) Then the investigation was carried out for each reason.
(4) Find out the reason.
(5) Solving problems.
The second step is critical, because the more possible reasons are found, the greater the success rate of error removal.
2. Error removal cases:
Sequential process is particularly important. It reflects a person's logical thinking. Here is a simple example to familiarize yourself with the specific steps.
As shown in the diagram, two AP are connected to a POE switch, a gateway device is connected to a POE switch, and a "cat" (modem) is connected to the gateway. Nowadays, customers only receive network signals on their mobile phones, but they can't connect to the Internet.
First of all, we should arrange errors in a certain order. Here we use the order from bottom to top to give an example.
When Wifi is not connected by mobile phone, we start from AP to analyze it step by step.
AP:
(1) POE switch does not supply power to AP, which will naturally lead to no signal after AP power off.
(2) In order to prevent rubbing, the SSID of AP is hidden and the signal can not be searched.
(3) AP performance, AP performance includes hardware and software, hardware is divided into CPU-function-antenna, if any part of the problem, may also lead to poor AP performance, so that no signal can be found.
POE switch:
(1) Hardware failure, resulting in power supply problems, AP no power, so no signal can be found.
(2) The problem of network leads to the problem of connection.
(3) The rate or mode of operation of switch ports do not match. Sometimes, when the traffic is too large, the rate is not enough, which leads to AP offline and no signal gateway can be found:
Gateway:
(1) Power failure, POE switch does not supply power.
(2) The unsuccessful dialing may be the incorrect username and password, the failure of dialing caused by the gateway's own configuration, or the arrears of network charges.
Analyzing so many reasons, we can test one by one, and the problem can be solved easily. However, now the customer situation is signal, can not access the Internet, so also have to go from bottom to top step by step. Mobile networking can actually be divided into two steps:
The first step is to scan SSID, that is, to find the name of the signal and the way of encryption, that is to say, to find the name of WIFI and enter the password.
The second step is to try to connect the mobile phone to the network.
(1) If signal instability occurs during the connection process, it may be the performance problem of AP, which includes the software part + the hardware part, or the signal instability caused by interference.
(2) If the IP acquisition is displayed in the connection process, which means that the mobile phone can access AP, that is, AP is electrified and works normally, then the AP and POE switches are normal;
(3) If IP can be acquired successfully, it means that DHCP function of the gateway intranet part, that is, the function of dynamically allocating IP address, is normal, then the gateway intranet part is no problem. However, the external part of the gateway can not be defined. Then only the gateway external network part to the "cat" section, can receive signals but can not access the Internet, analysis of the reasons, may be the wrong network plug-in, should plug in the gateway's external network interface (Wan port), otherwise can not access the external network, naturally can not access the Internet.
(4) Of course, there is also a common fault, that is, the problem of the wire. Problems occur in the process of making the crystal head of the wire, which will also lead to various situations that the network can not be connected.
First of all, we should arrange errors in a certain order. Here we use the order from bottom to top to give an example.
When Wifi is not connected by mobile phone, we start from AP to analyze it step by step.
AP:
(1) POE switch does not supply power to AP, which will naturally lead to no signal after AP power off.
(2) In order to prevent rubbing, the SSID of AP is hidden and the signal can not be searched.
(3) AP performance, AP performance includes hardware and software, hardware is divided into CPU-function-antenna, if any part of the problem, may also lead to poor AP performance, so that no signal can be found.
POE switch:
(1) Hardware failure, resulting in power supply problems, AP no power, so no signal can be found.
(2) The problem of network leads to the problem of connection.
(3) The rate or mode of operation of switch ports do not match. Sometimes, when the traffic is too large, the rate is not enough, which leads to AP offline and no signal gateway can be found:
Gateway:
(1) Power failure, POE switch does not supply power.
(2) The unsuccessful dialing may be the incorrect username and password, the failure of dialing caused by the gateway's own configuration, or the arrears of network charges.
Analyzing so many reasons, we can test one by one, and the problem can be solved easily. However, now the customer situation is signal, can not access the Internet, so also have to go from bottom to top step by step. Mobile networking can actually be divided into two steps:
The first step is to scan SSID, that is, to find the name of the signal and the way of encryption, that is to say, to find the name of WIFI and enter the password.
The second step is to try to connect the mobile phone to the network.
(1) If signal instability occurs during the connection process, it may be the performance problem of AP, which includes the software part + the hardware part, or the signal instability caused by interference.
(2) If the IP acquisition is displayed in the connection process, which means that the mobile phone can access AP, that is, AP is electrified and works normally, then the AP and POE switches are normal;
(3) If IP can be acquired successfully, it means that DHCP function of the gateway intranet part, that is, the function of dynamically allocating IP address, is normal, then the gateway intranet part is no problem. However, the external part of the gateway can not be defined. Then only the gateway external network part to the "cat" section, can receive signals but can not access the Internet, analysis of the reasons, may be the wrong network plug-in, should plug in the gateway's external network interface (Wan port), otherwise can not access the external network, naturally can not access the Internet.
(4) Of course, there is also a common fault, that is, the problem of the wire. Problems occur in the process of making the crystal head of the wire, which will also lead to various situations that the network can not be connected.