POE (Power Over Ethernet) refers to the technology that existing Ethernet Cat.5 cabling infrastructure without any changes can transmit data signals for some IP-based terminals (such as IP telephones, wireless LAN access point AP, network camera Etc.) while transmitting data signals, but also provide DC power supply for such devices. POE technology can ensure both the safety of existing structured cabling and normal operation of existing networks, which minimizes costs.POE power supply principleThe standard Category 5 cable has four pairs of twisted pairs, but only two of them are used in 10M BASE-T and 100M BASE-T. IEEE80 2.3af allows two kinds of usage, the application of idle feet power supply with, 4,5 feet connected to the positive and 7,8 feet connected to the negative.When the application of data feet power supplies power, the DC power supply in the midpoint of transmission transformer does not affect the data transmission. In this way the pair 1, 2 and the pair 3, 6 can b..
A simple definition of the fourth layer exchange is that it is a function that determines transmission based not only on the MAC address (the second layer network bridge) or source/destination IP address (the third layer routing) but also on TCP / UDP (the fourth layer) application port number. The fourth layer exchange's function is like a virtual IP, pointing to the physical server. It transmits services that are subject to a variety of protocols, including HTTP, FTP, NFS, Telnet, or other protocols.The principle of the fourth layer switchThe fourth layer of the OSI model is the transport layer. The transport layer is responsible for end-to-end communication, that is, communication coordinated between the network source and the target system. In the IP protocol stack, this is the protocol layer where TCP (a transport protocol) and UDP (user packet protocol) are.In the fourth layer, the TCP and UDP headers contain the port number, which uniquely differentiates which application protoc..
How to choose the switch for the HD monitor application?
Posted on Jun 30, 2017 by cozlink.com
Network monitoring system in our security occupies an absolute position. In the high-definition network video surveillance system, customers often have a feedback of the delay, Caton and other phenomena, caused for many reasons, but in most of the situation, they are caused by unreasonable switch configuration resulting in insufficient bandwidth. The switch is an indispensable device for the whole system. Whether it is properly configured or not directly affects the later stability of the network monitoring system.When selecting a switch, the backplane bandwidth and packet forwarding rate should be considered. The backplane bandwidth marks the total data exchange capacity of the switch. The higher the backplane bandwidth is, the stronger the ability to process the data. Packet forwarding rate also known as port throughput refers to the packet forwarding capacity of the router in a port. The higher the packet forwarding rate is, the better the performance.From the network topology, a la..
The difference between industrial switch and general switch
Posted on Jul 04, 2017 by cozlink.com
In terms of performance, industrial Ethernet switches and ordinary switches are not much different. From the network level, there are two switches, of course, there are three switches. Industrial Ethernet switch has a stress in its product design and component selection, which meets industrial field use needs. In the mechanical, climate, electromagnetic and other relatively poor circumstances, it is still able to work properly, so it can often widely used in the more harsh conditions of industrial production scenarios. So, what are the differences between industrial Ethernet switches and ordinary switches in the end?1. ComponentsThe selection requirements of industrial Ethernet switch components are higher, which should be able to better meet the needs of the industrial production site.2. Mechanical environmentIndustrial Ethernet switches are better able to adapt to harsh mechanical environments, including vibration resistance, impact resistance, corrosion resistance, dust prevention, ..