Test Access Point (TAP)

Introduction

A Test Access Point (TAP) is generally a device used to monitor and analyze network traffic without disrupting the normal operation of the network. It is typically placed between two Ethernet devices and operates transparently, allowing it to capture and mirror all the data passing through the connection. 

They play a crucial role in ensuring reliable and efficient communication between various components, such as programmable logic controllers (PLCs), human-machine interfaces (HMIs), and supervisory control and data acquisition (SCADA) systems. By monitoring the network traffic, TAPs help identify and troubleshoot issues related to communication protocols like OPC UA and PROFINET, which are widely used in industrial automation. 

Technical features of TAPs

A Test Access Point (TAP) provides a passive and non-intrusive way to access network traffic, offering several technical features that make it an essential tool for network monitoring and security, as follow: 

  • Physical Design

    A TAP has at least three ports: A and B, which connect to the network being monitored, and at least one monitoring port, which connects to a separate monitoring or analysis device. The key feature of a TAP is its ability to passively copy and forward network packets to the monitoring device without introducing latency or affecting the network's performance. 

  • Passive Monitoring

    Unlike active monitoring solutions, such as inline security appliances, a TAP operates passively. It doesn't interfere with the network's normal operation, making it an ideal choice for situations where network visibility is crucial without disrupting the flow of data. 

  • Full-Duplex Monitoring

    They support full-duplex monitoring, meaning they can simultaneously capture both incoming and outgoing traffic. This capability ensures that the monitoring device receives a complete picture of the network's activities. 

  • Enhanced Visibility

    It provides a comprehensive view of network traffic, allowing organizations to identify and analyze potential security threats, monitor bandwidth usage, and troubleshoot network issues effectively. 

  • Security and Forensics

    In the realm of cybersecurity, they play a critical role in detecting and preventing security breaches. By capturing all network packets, organizations can conduct in-depth forensic analysis to identify the source and nature of security incidents. 

  • Troubleshooting and Performance Monitoring

    It aids in troubleshooting network problems by providing real-time visibility into the flow of data. This is particularly valuable for diagnosing issues related to latency, packet loss, and overall network performance. 

  • Compliance and Regulation

    Many industries and organizations are subject to strict regulatory requirements regarding data privacy and security. It assists in meeting these compliance standards by ensuring thorough monitoring and documentation of network activities. 

Applications

Test Access Points (TAPs) have a wide range of applications in industrial automation and communication systems: 

Network Monitoring and Troubleshooting

They provide complete visibility into network traffic, allowing engineers to monitor and analyze data flowing through the network. This is particularly useful for troubleshooting communication issues between devices like PLCs, HMIs, and SCADA systems that use protocols such as EtherCAT and EtherNet/IP. By capturing all network packets, TAPs enable in-depth analysis to identify the root cause of problems related to latency, packet loss, and overall network performance. This helps minimize equipment downtime and ensures efficient operation of industrial automation systems. 

Security and Compliance

In the context of industrial cybersecurity, it plays a crucial role in detecting and preventing security breaches. By monitoring network traffic, organizations can conduct forensic analysis to identify the source and nature of security incidents. They assist in meeting regulatory requirements regarding data privacy and security by providing thorough monitoring and documentation of network activities. This is particularly important for industries subject to strict compliance standards. 

Remote Monitoring and Control

It supports secure virtual private network (VPN) connections, enabling remote monitoring and control of industrial equipment. This feature simplifies network management by offering switch capabilities without the need for additional devices. The ability to establish VPN connections reduces the need for on-site visits, saving time and resources. It also allows for quick response to issues, minimizing equipment downtime. 

Wireless Mesh Networking

They can be equipped with integrated antennas or external antennas to support wireless mesh networking (IEEE 802.11s) with WPA3-SAE encryption. This feature is particularly useful in mobile applications, such as connecting two separate LAN networks or making machine data directly accessible on handheld devices like tablets. 

Media Conversion and Aggregation

TAPs are available in various media types, including copper or fiber, and can perform media conversion. This flexibility allows TAPs to be deployed in diverse network environments, ensuring compatibility with existing infrastructure. They can also aggregate multiple network links into a single monitoring stream, simplifying the setup and reducing the number of monitoring ports required. This feature is beneficial in scenarios where multiple network segments need to be monitored simultaneously. 

Hilscher's netMIRROR TAP solution

Ethernet networks are preferred in industrial environments for their speed, scalability, and robustness, essential for seamless communication between devices like controllers, sensors, and actuators. However, their complexity necessitates continuous, non-disruptive monitoring. Traditional methods that split Ethernet connections for analysis often cause disruptions. To address this, Hilscher developed the netMIRROR TAP, which integrates seamlessly into existing networks, providing real-time traffic mirroring without interruptions. Its passive construction ensures that network traffic remains unaffected even if the TAP or diagnostic device fails, maintaining critical network uptime. Unlike traditional network switches that may lose packets under high loads, the netMIRROR TAP maintains timing and data integrity, crucial for real-time control systems and video communications. Combined with separate analysis and diagnostic tools such as Hilscher's netANALYZER, the netMIRROR provides the data basis for robust diagnostic functions that enable network administrators to monitor performance, detect security threats and continuously analyze communication errors. 

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