The Practical Application of Virtual Local Area Network
Distributed monitoring based on a virtual local area network includes an upper computer (industrial computer, network communication components), lower computer (industrial computer, network communication components, signal acquisition components), and monitoring terminal (office computer), the upper computer is responsible for data monitoring, the lower computer is responsible for on-site monitoring, and the monitoring terminal is responsible for management and analysis. In the network configuration mode, it is necessary to set several lower computer external network IP addresses and upper computer IP addresses in the same network segment to form a virtual local area network.
In the virtual local area network, the lower computer can be connected to the driver through the terminal block, read the instrument setting parameters, and convert the parameters into displayable values, such as pressure, temperature, etc. At the same time, the on-site collected data will be sent to the INT network via ADSL MODEM. The INT network can transmit data to the upper computer through routers, fiber optic transceivers, and network switches. The upper computer can transmit the data to the monitoring terminal, and send the analyzed instructions of the monitoring terminal to the lower computer to realize distributed monitoring. The monitoring terminal can check the site, historical operation data, and various charts at any time, discover site faults in time and propose solutions based on data trends.
Process Level Management
The intelligent network architecture includes three levels of station control, interval, and process layer, involving station control and process layer networks. The process layer network gathers intelligent terminals and merging units, reduces the length of the loop, and can transmit information through optical media and interval layer equipment. interact. In the process layer network, SV (sampling value information) is the main transmission information, which requires a transmission rate of 4000 frames/s, and the transmission volume is large, which can easily cause broadcast storms. Based on this, IEEE802 can be used. 1Q is additionally marked with virtual LAN information to divide virtual LANs, filter packets, and avoid broadcast storms. The virtual local area network information in the message is identified as target MAC address, source MAC address, TPID, TCP, type, data part, and CRC, where the target MAC address is 6 bit/s; the source MAC address is 6 bit/s; TPID (0 × 8 100) is 2 bit/s; TCP (contains 12 bit/s VLAN information identification) is 2 bit/s, including User priority( 3 bit/s), CFI( 1 bit/s), VLAN ID ( 12 bit / s ) ; type is 1 bit / s; data part is 46 ~ 15 006 bit / s; CRC is 4 bit / s.
In order to filter packets smoothly, you can set several switch VLAN IDs to only correspond to 1 Port – base VLAN ID, so that when an untagged data packet is received, the VLAN label will be automatically “pasted”, and the untagged port of the switch will receive the data packet or send the untagged data Bag. At this time, when the dynamic query message information does not increase, the switch is not responsible for the Layer 2 multicast management protocol, nor will it dynamically change the network division, and the network message flow is significantly reduced.
After inserting the VLAN TAG tag field in the standard Ethernet frame, the construction of a virtual local area network can be realized. In essence, Virtual LAN is a technology that logically divides a real broadcast domain LAN in physical space into several completely isolated sub-broadcast domains, which can prevent the leakage of security information and reduce the risk of viruses while reducing the consumption of host hardware resources.
Flood the risk of spreading and provide users with a good experience. Therefore, corresponding technicians can use ACL, PAT, and DHCP technologies to logically divide and isolate sub-broadcast domains according to the application requirements of virtual local area networks, so as to provide a secure network environment for the development of various industries.
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