In the world of industrial networks, VLANs (Virtual Local Area Networks) are like independent "office areas", and devices in different VLANs are like employees working in different offices, unable to communicate directly with each other by default. However, in practical production scenarios, it is often necessary to break this restriction and enable devices with different VLANs to communicate, at which point industrial switches play a critical role. Next, we will delve into how industrial switches achieve cross VLAN communication.
1、 What is VLAN and cross VLAN communication
VLAN is a software technology that logically divides a physical LAN into multiple broadcast domains. After dividing VLANs, devices in different VLANs are like being separated in different network "small rooms" and cannot communicate directly with each other, which can improve network security and management efficiency. For example, in a factory, the production department, monitoring department, and office department can be assigned to different VLANs to avoid mutual interference.
However, in practical applications, different departments sometimes need to share data and collaborate, which requires breaking down the "isolation wall" between VLANs and achieving cross VLAN communication. For example, equipment on the production line (located in the production VLAN) needs to transmit data to servers in the monitoring room (located in the monitoring VLAN), which involves cross VLAN communication.
2、 Common methods for achieving cross VLAN communication in industrial switches
1. Single arm routing
Single arm routing is like building a shared "corridor" between different VLAN "rooms". Industrial switches are connected to routers through a physical interface, which is configured as a trunk interface and can carry data from multiple VLANs. Create sub interfaces for each VLAN on the router, with each sub interface corresponding to a gateway for a VLAN. Data is forwarded through the router's sub interfaces to achieve cross VLAN communication.
In practical operation, the first step is to set the port connected to the router on the industrial switch to trunk mode, similar to the command switchport mode trunk. Then, on the router, create sub interfaces for each VLAN and configure the IP address as the gateway for the VLAN, for example interface GigabitEthernet0/0.1 、encapsulation dot1Q 10 、ip address 192.168.10.1 255.255.255.0 （ Assuming VLAN ID is 10.
However, single arm routing also has its drawbacks, as all cross VLAN data must pass through a physical interface of the router, which can easily create a network bottleneck. Moreover, once the router fails, the entire cross VLAN communication will be interrupted.
2. Three layer exchange
Layer 3 switching technology is like installing "intelligent navigation" on industrial switches, giving them routing capabilities. The three-layer switch integrates a routing module internally, which can directly configure the IP address of the VLAN interface on the switch as a gateway for each VLAN. When data needs to be transmitted across VLANs, layer 3 switches directly forward the data internally by searching the routing table, without the need for external routers.
When configuring layer 3 switching to achieve cross VLAN communication, first create VLANs on the switch, such as VLAN 10 and VLAN 20; Then divide the corresponding ports into VLANs, such as interface Gigabit Ethernet 0/1, switchport access VLAN 10; Then configure IP addresses for each VLAN, such as interface Vlan10 and IP address 192.168.10.1 255.255.255.0.
The advantages of layer 3 switching are obvious, with fast data forwarding speed, high performance, no bottleneck problems like single arm routing, relatively simple configuration, and higher reliability. It is currently a commonly used method for achieving cross VLAN communication in industrial networks.
3. Multi interface routing of routers
This method is to configure a physical interface for each VLAN on the router, with each interface connected to the corresponding VLAN port on the industrial switch, and each interface serving as a gateway for the corresponding VLAN. When data is transmitted from one VLAN to another, it is forwarded through different physical interfaces of the router.
When configuring, it is necessary to configure IP addresses for each interface on the router, such as interface Gigabit Ethernet 0/0, IP address 192.168.10.1 255.255.255.0 (assuming corresponding to VLAN 10), and configure the ports connected to the router interface in Access mode on the switch and assign them to the corresponding VLAN. However, this method requires more router interfaces, is costly, and has poor scalability.
3、 Choose an appropriate cross VLAN communication solution
When choosing an industrial switch to implement cross VLAN communication, it is necessary to comprehensively consider factors such as network size, budget, and performance requirements. If the network scale is small and cost sensitive, single arm routing is an economical choice; For medium-sized networks with certain performance requirements, layer 3 switching is a better solution; The multi interface routing of routers is generally suitable for some special small network scenarios due to cost and scalability issues.
By understanding the methods of implementing cross VLAN communication through these industrial switches, we can build more efficient and flexible industrial networks according to actual needs. I hope this article can help you understand the principles and implementation methods of cross VLAN communication. If you have any problems in practical operation, please feel free to communicate and discuss at any time.
The above introduces cross VLAN communication solutions for industrial switches from various perspectives. If you want to know the specific case of a certain solution or have any other network technology issues, please feel free to let me know at any time.