Feature Introduction – Quality of Service (QoS) Prioritize Critical Communication on Premium Unmanaged Ethernet Switches
Author: Jonas Gesch
Job Title: Field Application Engineer
Industrial Ethernet networks are built to offer the best possible reliability when it comes to data availability for mission-critical processes. While features for traffic monitoring and management are commonly available in managed Ethernet switches, unmanaged switches typically don't offer any such features. This is why the Premium Unmanaged Ethernet Switch series offered by Volktek is in a unique position to provide improved reliability for industrial communication without the need to switch to more costly managed Ethernet switches.
These features work quietly in the background and don't require any configuration, keeping the switch plug&play. These premium features include Class of Service (CoS), industrial QoS (iQoS) and Port Priority, which all directly contribute to improving the Quality of Service (QoS) for network communication by prioritizing critical data packets.
If an industrial network experiences a high traffic load, this might fill the receive buffer of a switch faster than it is capable of sending out the data packets. Since a receive buffer is limited in size, it will eventually overflow and have no more space for additional incoming packets, forcing the switch to drop them. This can result in packet loss and communication disruptions, which in turn lead to delays in receiving data or even system downtime.
In industrial networks, these interruptions are to be avoided at all costs, especially for safety critical applications. Traffic loads have been steadily increasing in industrial networks with SCADA system retrieving high amounts of device data for monitoring and control processes starting to move from PLCs to IPCs, which is why it is important to proactively protect mission-critical communication.
QoS offers a way to mitigate unfavorable network conditions by identifying mission critical data packets and ensuring that the switch will handle and send them out first by prioritizing them over ordinary network traffic. This enhances the performance of industrial communication protocols.
Volktek's Premium Unmanaged Ethernet Switch series offers three QoS features which take effect on the following order:
Industrial Ethernet networks often utilize special industrial communication protocols for reliable and timely data transmission between end-devices. With Industrial QoS (iQoS), Volktek's Premium Unmanaged switches are capable of automatically detecting if a data packet belongs to an industrial protocol like PROFINET, Ethernet/IP or GOOSE. These packets are then sent to the front of the egress queue to ensure minimum delay and avoid packet loss.
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Figure 1: Prioritization of industrial protocols with iQoS
Another method of prioritizing critical data packets is defined in the IEEE standard 802.1p and is referred to as Class of Service (CoS). It can be applied to data packets with a 802.1Q VLAN tag by setting the value of the 3-bit field in the VLAN tag. This field is referred to as the Priority Code Point (PCP) and can hold values of 0 to 7, which refer to the priority with which the packets are handled. Packets with PCP 7 are treated with the highest priority used for network control and PCP 1 represents background traffic with the lowest priority while PCP 0 is the default priority and gets transmitted with best effort. The values in between are conventionally assigned to different classes of traffic like video, voice or critical applications.
Figure 2: Traffic prioritization with Class of Service
Since CoS is inherently tied to VLAN tagging, it relies on other network devices like managed switches to set those VLAN tags and assign the PCP value. To make the best use of CoS in an industrial network that contains both managed and unmanaged switches, it is highly beneficial to use Premium Unmanaged Ethernet Switches, that can both retain the VLAN tag and use the embedded CoS information to prioritize packets according to their PCP values.
The last prioritization criteria applied to packets on Volktek's Premium Unmanaged Ethernet Switches is Port Priority. This feature will prioritize ingress traffic on specific interface ports of the switch, offering enhanced performance for critical devices by simply physically connecting them to a prioritized port. Premium Unmanaged switches with 4-5 RJ45 ports will prioritize port 1, 8 RJ45 port switches prioritize ports 1-2 and switches with 16 RJ45 ports prioritize ports 1-4.
Figure 3: Critical devices connected to priority ports
A: No, the QoS features work silently in the background and don't need to be enabled.
A: QoS can improve critical communication during a high traffic load on the network to avoid packet loss and connection disruptions.
A: Industrial QoS prioritizes PROFINET, Ethernet/IP and GOOSE packets.
A: No, these features are not commonly available on basic unmanaged switches and are specifically implemented on Volktek's Premium Unmanaged switches to increase reliability in industrial networks.
Volktek Corporation is a Taiwan-based manufacturer specializing in industrial Ethernet networking solutions with more than three decades of experience in supporting industrial automation, building management system, maritime, transportation, energy, and critical infrastructure applications. Volktek focuses on delivering reliable, secure, and easy-to-deploy networking products that operate consistently in harsh industrial environments.
With in-house design, manufacturing, and quality control, Volktek supports customers worldwide through the full product lifecycle—from system design and deployment to long-term operation and technical support. Our portfolio emphasizes robustness, long product availability, and practical security features to help customers build resilient and future-ready OT networks.
