VLAN 802.1Q is a networking standard that allows multiple virtual LANs (VLANs) to share a single physical network interface. It is the basis for VLAN tagging—an essential component in building secure, segmented, and scalable infrastructures.
What is VLAN 802.1Q? #
IEEE 802.1Q is the most widely used standard for implementing VLANs in Ethernet networks. It introduces a 4-byte VLAN tag into Ethernet frames to identify the VLAN to which the packet belongs. This mechanism allows network devices—such as switches, routers, and application delivery controllers (ADCs)—to properly segregate and route traffic.
- VLAN ID: A 12-bit field in the tag that supports up to 4094 VLANs (IDs 1–4094).
- Priority Code Point (PCP): A 3-bit field for traffic prioritization (used in QoS).
- Tag Control Information (TCI): Encapsulates VLAN ID and PCP for network processing.
What is VLAN Tagging? #
VLAN tagging is the process of inserting the 802.1Q tag into Ethernet frames as they traverse trunk ports between network devices. These tags are read and processed by compatible devices to ensure traffic remains isolated within its VLAN.
There are two key types of ports:
- Access Ports: Carry traffic for a single VLAN without tagging.
- Trunk Ports: Carry traffic for multiple VLANs using 802.1Q tags.
Why VLAN Tagging Matters in Load Balancing #
In modern networks—especially in multitenant architectures or when separating internal vs. external traffic—VLAN tagging is essential for maintaining traffic isolation and simplifying policy enforcement.
Use Cases with Load Balancing: #
- Multi-tenant ADC deployments: Each tenant’s traffic is isolated using different VLANs.
- Internal vs. DMZ segmentation: Separate backend server traffic from external client requests.
- High Availability across VLANs: Syncing stateful sessions in HA clusters across segmented networks.
RELIANOID and VLAN Tagging #
RELIANOID ADC supports 802.1Q VLAN tagging natively, allowing seamless deployment in complex network environments. This capability enables administrators to:
- Create virtual interfaces with specific VLAN IDs.
- Bind virtual services (VIPs) to VLAN-tagged interfaces.
- Route and load balance traffic per VLAN, applying specific rules and health checks.
- Integrate with both access and trunk port topologies.
Once the VLAN interface is created, it can be used as the source for Virtual IPs (VIPs) or backend server groups in RELIANOID’s configuration.
Architecture Diagram (Simplified) #
Example setup using VLANs and RELIANOID:
- VLAN 10 → Public client traffic (Internet)
- VLAN 20 → Internal application servers
- VLAN 30 → Monitoring and management network
RELIANOID can route and load balance between these VLANs securely, ensuring that backend communication is isolated while still providing availability and performance optimization to external clients.
Best Practices for VLAN + Load Balancing #
- Ensure switches are correctly configured to trunk the appropriate VLANs to the RELIANOID interfaces.
- Use consistent MTU settings across devices to avoid fragmentation issues.
- Isolate management VLANs from data VLANs for improved security.
- Use VLAN tagging in HA setups to separate sync and health-check traffic.
Conclusion #
802.1Q VLAN tagging is a foundational feature for designing secure, segmented, and high-performance networks. RELIANOID supports this natively, making it an ideal ADC platform for environments that require strong isolation, tenant separation, or flexible network design. Whether you’re scaling infrastructure or implementing Zero Trust principles, VLAN tagging with RELIANOID ensures you’re building on a robust and secure foundation.
Resources #
RELIANOID Enterprise Edition VLAN Tagging Configuration
