After installing monitoring, the network often drops

yishuihanpo

After installing monitoring, the network often drops [Copy link]

 

The company has installed monitoring. There was no problem for some time, but in the past month, DNS service errors have frequently appeared, prompting to modify DNS. Various modification methods are useless. Refer to the picture for the structure of the network. You need to restart the router or optical modem frequently before you can access the Internet normally for a short while. For this reason, I changed the router and installed a switch, but it didn’t work. I unplugged the network cable of the hard disk drive yesterday, and the network speed returned to normal. It still doesn’t work after plugging it in Please take a look at this network structure. Is the switch placed in the right position?

aaron2018

1. DNS server error, on which device? 2. What is the network configuration of the DVR?

白丁

Is there a public IP?

qwqwqw2088

The problem should be on the optical modem and router, and then we can rule it out. Some time ago, a port failure on our router affected the entire network.

yishuihanpo

aaron2018 posted on 2018-8-6 19:13 1. DNS server error, on what device? 2. DVR network configuration?

Hi, it is prompted on the computer, and then the entire network cannot be used, but the LAN can be used.

yishuihanpo

Bai Ding posted on 2018-8-6 19:54 Is there a public IP?

Hello, there is no public IP.  

yishuihanpo

qwqwqw2088 posted on 2018-8-6 20:47 The problem should be on the optical modem and the router, and then we can rule it out. Some time ago, a port failure on our router affected the entire network

It's actually very strange. The problem started a few days after the telecom changed the optical modem. But the telecom people came and what they said made sense. It was fine to connect to the optical modem and dial up to the Internet for a whole day. But it stopped working when the hard drive for monitoring was connected.

qwqwqw2088

yishuihanpo posted on 2018-8-7 07:51 It is actually very strange. The problem started a few days after the telecom company replaced the optical modem. But the telecom people came and what they said made sense. Just connect the optical modem and dial...

Disconnect the hard drive temporarily and check if there is any problem with the connection cable. There must be a problem with some hardware. The most common problem with network equipment in summer is the connection, which may be caused by humidity, heat expansion, looseness, aging, etc.

yishuihanpo

qwqwqw2088 posted on 2018-8-7 07:56 Temporarily disconnect the hard disk drive and check if there is any problem with the connection cable. It must be a hardware problem. The most likely problem with network equipment in summer is...

Yes, the temperature is relatively high. I disconnected the hard disk drive since yesterday. So far, everything is normal, but the hard disk drive can't record~

chunyang

It is likely the result of a network broadcast storm, which is related to the poisoning of certain terminals, network port failure, configuration errors, etc. You may wish to use network packet monitoring software to see which terminals are sending data crazily when the fault recurs, and then focus on checking the corresponding terminal devices.

yishuihanpo

chunyang posted on 2018-8-7 12:12 It is probably the influence of network broadcast storm, which is related to the poisoning of some terminals, network port failure, configuration error, etc. You may want to use network packet monitoring software to...

Tested, there is no particularly obvious questionable data packet when the network has problems, but the router's 239.255.255.250 is quite frequent.

topwon

Repost: When learning how to capture packets with wireshark, I found that the router would send packets to 239.255.255.250 every 20 seconds. Baidu found out that it was because the UPnP service was enabled on the router, and this service would use SSDP (Simple Service Discovery Protocol), which is the multicast address port 1900 of 239.255.255.250, to discover the UPnp service. If there is a UPnP service on a computer in the LAN, this machine will announce to the multicast address that the service is available on the network at regular intervals, and the sending method is HTTP multicast based on UDP. Solution: Turn off the UPnP service in the forwarding protocol settings on the router.

chunyang

yishuihanpo posted on 2018-8-7 16:47 After testing, there are no particularly obvious suspicious data packets when the network has problems, but the router's 239.255.255.250 is quite frequent

For the sudden frequent multicast packets, it can be judged that a virus has been infected or a program containing a Trojan has been installed. Finding the source for processing means paying attention to analyzing the application software installation behavior and network access history of the problem node to find out the cause of the problem and prevent the problem from recurring.

无极限

The DVR may have a virus, causing a large number of broadcasts and increasing network pressure. Resetting and cleaning the DVR may solve the problem.