Industrial Ethernet Switches: In-Depth Practice of Network Segmentation and Security Isolation
In today's era of deep integration between intelligent manufacturing and the Industrial Internet, industrial Ethernet switches have evolved from mere data transmission devices into core infrastructure for ensuring industrial network security. Facing increasingly complex network threats in scenarios such as oil extraction, rail transit, and intelligent manufacturing, constructing a "defense-in-depth" system through network segmentation and security isolation strategies has become a critical proposition determining the reliability of industrial control systems.

1. Strategic Value of Network Segmentation: From Flat Networks to Three-Dimensional Defense
1.1 VLAN Technology: The Foundation of Logical Isolation
Virtual Local Area Networks (VLANs) achieve broadcast domain isolation by dividing physical networks into multiple logical subnets. In a DCS system upgrade project at a refinery, the USR-ISG series switches were used to segment the production network (VLAN10), office network (VLAN20), and monitoring network (VLAN30), combined with 802.1X authentication, resulting in zero occurrences of network security incidents. This isolation strategy effectively blocks the penetration path of office network viruses into production control systems.
At the technical implementation level, VLANs require coordination with Layer 3 switches to enable cross-subnet communication. For example, in an automotive manufacturing workshop, the USR-ISG1005's five Gigabit ports were used to segment the welding robot control network (VLAN100) and visual inspection network (VLAN200). Its 10Gbps backplane bandwidth ensures synchronized transmission of high-definition image data and motion control instructions.
1.2 Subnet Segmentation: Fine-Grained Traffic Control
Subnet segmentation restricts device access ranges through IP address planning. In an 800-kilometer natural gas pipeline project, a three-tier architecture of "control center-distribution station-valve chamber" was adopted: the control center's core switch segments the 10.0.0.0/16 production subnet, the distribution station's aggregation switch segments the 10.1.0.0/24 regional subnet, and the valve chamber's industrial switch segments the 10.1.1.0/28 terminal subnet. This design reduced leak detection response time from 30 minutes to 5 minutes and cut annual manual inspection mileage by 20,000 kilometers.
The choice of subnet masks requires balancing host quantity and security needs. In rail transit signaling systems, a 255.255.255.0 mask was used to segment station subnets, meeting the access needs of 254 devices while restricting cross-station access via ACLs, reducing signaling system failure rates by 67%.
1.3 Port Isolation: Security Boundaries Within the Same VLAN
Port isolation technology breaks through traditional VLAN limitations, enabling Layer 2 isolation of devices within the same subnet. In a smart manufacturing workshop project, the USR-ISG208S-SFP switch's port isolation function was used to segment PLCs (ports 1-4) and HMIs (ports 5-8) into different isolation groups. Even when physically connected to the same VLAN, PLC instructions could not be illegally tampered with. This design reduced the risk of misoperations during equipment debugging by 82%.
Configuration requires careful selection of isolation modes: L2 mode allows Layer 3 intercommunication, suitable for scenarios requiring cross-device data collection; ALL mode provides complete isolation, ideal for military production environments with high confidentiality requirements.

2. Three-Dimensional Defense of Security Isolation: From Boundary Protection to Defense-in-Depth
2.1 Firewall Integration: Intelligent Gateways at Network Boundaries
Modern industrial switches integrate firewall functions to achieve deep packet inspection. In a desert oilfield wellhead monitoring project, the firewall module of USR-ISG series switches could identify and block Modbus protocol injection attacks, with its stateful inspection engine achieving a 99.3% interception rate for unauthorized access. This embedded firewall reduces deployment costs by 30% compared to traditional hardware firewalls.
Policy configuration must adhere to the principle of least privilege. In power dispatching systems, firewall rules restrict dispatch terminals to accessing only specific ports of the SCADA system, reducing APT attack success rates by 76%.
2.2 ACL Access Control: Precision Guidance for Traffic Management
Access Control Lists (ACLs) finely control traffic through parameters such as source/destination IP, port numbers, and protocol types. In a steel enterprise's blast furnace control system, the USR-ISG switch's ACL function restricted engineer stations to accessing only PLC port 48899 (Profinet protocol), preventing the spread of ransomware targeting Windows systems. Rule configuration should adopt a "default deny, allow as needed" strategy, elevating security levels compared to traditional "default allow" modes.
Time-dimension control represents an advanced ACL application. In chemical reactor control systems, ACL rules restrict parameter modification operations to authorized IPs between 8:00-17:00, reducing misoperations during non-working hours by 91%.
2.3 Physical Isolation: The Security Baseline for Extreme Environments
For high-risk scenarios like explosion-proof areas, physical isolation remains the last line of defense. A refinery adopted the USR-BAG208BS-SFP explosion-proof switch, with its 6000V lightning protection design and IP67 protection rating ensuring stable operation in flammable gas environments. The combined use of physical and logical isolation has resulted in three consecutive years without network-induced safety incidents at this plant.
Fiber optic ring networks further enhance physical isolation. In long-distance pipeline projects, the USR-ISGX424-SFP switch's 80km single-mode fiber transmission constructs a physically isolated ring network of "control center-distribution station-valve chamber," limiting the impact range of single-point failures to within 20km.

3. Solution for Typical Scenarios: Bridging Theory and Practice
3.1 Petroleum Industry: High-Reliability Networking in Extreme Environments
In upstream oil and gas extraction scenarios, the USR-BAG208BS-SFP explosion-proof switch addresses summer overheating issues in desert oilfields through its -40℃~75℃ wide temperature design and ERPS ring network protocol (<50ms self-healing). After deployment, one oilfield achieved 18 consecutive months of zero-fault operation, reducing annual economic losses by 1.2 million yuan.
Midstream pipeline scenarios adopt a "fiber optic + industrial switch" hybrid architecture. The USR-ISGX424-SFP switch's 10Gbps SFP optical ports support 80km transmission, combined with EN 61000-6-2 electromagnetic compatibility rating to effectively resist strong electromagnetic interference along pipelines.
3.2 Intelligent Manufacturing: Balancing Real-Time Performance and Security
Automotive manufacturing workshops demand extremely low network latency. The USR-ISG1005 switch's 5μs packet forwarding delay meets the real-time transmission needs of welding robot motion control instructions. Its VLAN segmentation isolates the robot control network (VLAN100) from the AGV scheduling network (VLAN200), reducing production line downtime by 63%.
Edge computing integration represents the development direction. The next-generation USR-ISG series plans to integrate TSN (Time-Sensitive Networking) technology, achieving microsecond-level time synchronization through IEEE 802.1AS protocol to support high-precision control scenarios like multi-axis coordination.
3.3 Rail Transit: Ensuring High Availability
In metro signaling systems, the USR-ISG208S-SFP switch's dual power redundancy design (9.6~60V wide voltage input) and MSTP ring network protection ensure continuous operation of signaling systems during single power failures or link interruptions. After application in a city metro project, signaling failure rates dropped from 2.3 monthly incidents to 0.1.

4. Future Trends: From Passive Defense to Active Immunity
4.1 AI-Empowered Security Operations
Machine learning-based traffic anomaly detection is emerging. The next-generation USR-ISG series plans to integrate an AI engine, analyzing historical attack patterns to enable early warning of unknown threats. A pre-research project demonstrated that AI detection reduced discovery time for zero-day vulnerabilities from 72 hours to 15 minutes.
4.2 Deep Integration of Zero Trust Architecture
The Zero Trust concept mandates "default distrust, always verify." The USR-ISG series is developing a dynamic policy engine that adjusts access permissions in real-time based on contextual information such as device behavior, time, and location. Pilot implementations in power monitoring systems show an 89% reduction in lateral movement attack success rates.
4.3 Exploration of Quantum Encryption Technology
Facing quantum computing threats, research into post-quantum cryptography (PQC) algorithms has commenced. Subsequent USR-ISG series products may integrate the NIST-standardized CRYSTALS-Kyber algorithm, providing quantum-secure encryption protection for industrial control systems.

5. Building an Immune System for Industrial Networks
The network segmentation and security isolation strategies of industrial Ethernet switches have evolved from isolated technical measures into a three-dimensional defense system spanning the physical, data link, and network layers. Practices with the USR-ISG series switches in petroleum, manufacturing, and transportation sectors demonstrate that through comprehensive application of VLAN segmentation, subnet isolation, firewall integration, and other technologies, an industrial network immune system with "self-awareness, self-defense, and self-recovery" capabilities can be constructed.
With the convergence of TSN, AI, Zero Trust, and other technologies, industrial switches are evolving from data forwarding devices into intelligent security platforms. This evolution represents not merely technological iteration but a critical support for the transformation of industrial control systems from "passive protection" to "active security." In the wave of the Industrial Internet, mastering core technologies of network segmentation and security isolation has become a strategic imperative for enterprises to build digital competitiveness.