Practical Guide to VLAN Division in Ethernet Switche: Configuration Tutorial for Isolating Traffic from Different Workshop Equipment
Introduction: The Urgent Need for Industrial Network Traffic Isolation
In today's era where smart manufacturing is sweeping across the globe, industrial networks have become the core hub connecting production equipment, monitoring systems, and management platforms. However, with the rapid increase in the number of devices and the diversification of business types, the traditional "one-network-for-all" deployment approach is facing severe challenges: traffic from devices in different workshops is mixed within the same broadcast domain, leading to frequent broadcast storms, increased latency for critical services, and even production accidents caused by unauthorized access. A case study from an automobile manufacturing plant revealed that in an unisolated industrial network, the downtime loss caused by a broadcast storm on a single production line could reach as high as 500,000 yuan per hour.
VLAN (Virtual Local Area Network) technology, by logically dividing the network, isolates traffic from devices in different workshops into independent broadcast domains, becoming a key tool to address this pain point. This article will combine practical cases to deeply analyze the configuration methods for VLAN division in Ethernet switche and recommend the USR-ISG series Ethernet switche as an implementation solution.

1. Core Value of VLAN Technology: From "Mixed Living" to "Separate Rooms"

1.1 The Terminator of Broadcast Storms

In traditional industrial networks, all devices share the same broadcast domain, leading to an ubiquitous presence of broadcast packets such as ARP requests and DHCP discoveries. For example, in a network composed of 200 devices in an electronics factory, the number of broadcast packets per second exceeded 5,000, occupying 30% of the bandwidth and directly causing video surveillance stuttering. Through VLAN division, the broadcast domain can be reduced to the workshop level, reducing the number of broadcast packets by over 90%.

1.2 The Firewall for Security Isolation

Devices in different workshops may involve data of different security levels. For instance, PLC control instructions in the welding workshop belong to core production data, while barcode scanner data in the packaging workshop is ordinary business traffic. Through VLAN isolation, low-security-level devices can be prevented from accessing high-security-level networks through means such as ARP spoofing. A practice in a chemical enterprise showed that VLAN isolation reduced the success rate of network attacks by 76%.

1.3 The Optimizer for Bandwidth Utilization

In mixed deployment scenarios, high-traffic devices (such as video transmissions from AGV trolleys) may squeeze the bandwidth of critical control instructions. By marking VLAN priorities (such as IEEE 802.1p), real-time control data (such as robot motion instructions) can be ensured to receive the highest transmission priority. Tests at a logistics center showed that the latency for critical services was reduced from 50ms to less than 5ms.

2. Methodology for VLAN Division: In-Depth Analysis of Three Mainstream Technologies

2.1 Port-Based VLAN: The Simplest and Most Direct Isolation Method

Principle: Physical ports of the switch are divided into different VLANs, and devices connected to these ports belong to the corresponding VLAN.
Applicable Scenarios: Workshops with fixed device locations and simple network topologies, such as assembly lines and painting lines.
Configuration Example (using USR-ISG switches as an example):

Advantages: Simple configuration, suitable for small to medium-sized networks; Limitations: Device movement requires reconfiguration of ports.

2.2 MAC Address-Based VLAN: Automatic Following for Mobile Devices

Principle: A device's MAC address is bound to a VLAN, and regardless of which port the device is connected to, it automatically joins the corresponding VLAN.
Applicable Scenarios: Devices that require frequent movement, such as AGV trolleys and handheld terminals.
Configuration Example:

Advantages: No reconfiguration required for device movement; Limitations: MAC addresses can be forged, requiring the use of 802.1X authentication in conjunction.

2.3 IP Subnet-Based VLAN: Intelligent Shunting of Multi-Service Traffic

Principle: VLANs are divided based on the source IP address or subnet of data packets, suitable for IP-enabled devices (such as smart cameras and IoT sensors).
Applicable Scenarios: Scenarios requiring isolation by business type, such as video surveillance networks and device control networks.
Configuration Example:

Advantages: Automatic shunting by business; Limitations: Requires device support for the IP protocol stack.

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3. USR-ISG Ethernet Switch: The Ideal Platform for VLAN Division

In industrial scenarios, the reliability, environmental adaptability, and functional integrity of switches are key to the successful deployment of VLANs. The USR-ISG series Ethernet switches are designed specifically for harsh environments and offer the following core advantages:
Industrial-grade protection: IP40 protection rating, wide temperature operation from -40°C to 85°C, and 6000V lightning protection, adapting to extreme environments such as outdoors and explosion-proof areas;
Flexible port configuration: Supports a hybrid topology of 8 electrical ports + 2 optical ports, meeting both short-distance device access and long-distance backbone transmission needs simultaneously;
Enhanced VLAN functionality: Supports VLAN division based on ports, MAC addresses, and IP subnets, and can configure inter-VLAN routing (requires Layer 3 switch support);
Intelligent management: Managed through multiple methods such as Web, CLI, and SNMP, supporting batch import/export of VLAN configurations, significantly reducing operational and maintenance costs.
Case Study from a Steel Plant: By deploying USR-ISG switches, traffic from devices in the blast furnace, rolling mill, and warehousing workshops was isolated into different VLANs, improving network availability to 99.99% and reducing annual fault occurrences from 12 to 1.

4. VLAN Configuration Pitfalls Guide: Key Details in Practical Applications

4.1 The "Allow List" Trap for Trunk Ports

Incorrect Configuration: port trunk allow-pass vlan all
Consequence: All VLAN traffic passes through the Trunk port, leading to isolation failure.
Correct Approach: Only allow necessary VLANs to pass through, such as:

4.2 The Dual Identity of Native VLAN

Risk: Traffic from the Trunk port's Native VLAN (default VLAN 1) is untagged and may be exploited by illegally connected devices.
Solution: Modify the Native VLAN to a non-business VLAN and disable VLAN 1:

4.3 The "Invisible Bottleneck" of Inter-VLAN Routing

Problem: Communication between different VLANs requires a Layer 3 device (such as a router or Layer 3 switch). If QoS is not configured, it may lead to latency for critical services.
Optimization Suggestion: Configure policy-based routing on the Layer 3 device to allocate dedicated bandwidth for high-priority VLANs (such as device control networks).

5. Future Outlook: The Deep Integration of VLANs and Industrial Networks

With the rise of technologies such as TSN (Time-Sensitive Networking) and SDN (Software-Defined Networking), VLANs are evolving from static isolation to dynamic intelligent management. For example:
Dynamic VLAN Assignment: Automatically assign VLANs based on user identity through a RADIUS server;
Micro-segmentation: Further isolate critical devices within VLANs to achieve a "zero-trust" security architecture;
AI-Driven Traffic Optimization: Analyze traffic patterns based on machine learning to dynamically adjust VLAN division strategies.

6. Take Immediate Action to Build a Secure and Efficient Industrial Network

VLAN technology is a core means to address issues such as mixed industrial network traffic, high security risks, and low bandwidth utilization. By reasonably planning VLAN topologies, selecting suitable division methods, and leveraging the powerful functions of industrial-grade switches like USR-ISG, enterprises can significantly improve network reliability, security, and operational and maintenance efficiency.
Contact PUSR to obtain:

• A free industrial network VLAN planning solution;
• The USR-ISG switch product manual and configuration guide;
• A 30-day trial period to experience the ultimate effects of VLAN isolation firsthand.
  Let every workshop and every device have its own dedicated "network room," and propel industrial networks from "chaos and disorder" to "intelligence and efficiency"!