Virtual LAN (VLAN) and Inter-VLAN Routing Performance Analysis

Abstract

Virtual Local Area Networks (VLANs) are a foundational mechanism for logically segmenting switched networks into broadcast domains that align with organisational, security, or functional boundaries rather than physical wiring. Because hosts in different VLANs cannot communicate without a Layer 3 device, inter-VLAN routing is required whenever segmented networks must exchange traffic, and network designers commonly choose between two established approaches: Router-on-a-Stick (RoAS), in which a single router interface carries tagged traffic for multiple VLANs over sub-interfaces, and Switched Virtual Interface (SVI) routing on a Layer 3 switch, in which routing is performed in hardware using an internal virtual interface per VLAN. This paper presents a performance analysis of these two inter-VLAN routing architectures, evaluated through a simulation-based experimental design using packet-per-second throughput, end-to-end latency, jitter, and packet loss as the primary metrics under varying traffic loads. Building on configurations and metrics reported in existing networking literature and vendor documentation, this study develops a structured test topology, a repeatable measurement methodology, and a comparative analysis framework suited to a laboratory or campus-network setting. The analysis indicates that SVI-based inter-VLAN routing consistently outperforms Router-on-a-Stick in throughput and latency because routing decisions are made in application-specific hardware rather than in a shared-bandwidth software path, while Router-on-a-Stick retains advantages in initial cost and configuration simplicity for small networks with few VLANs. The paper concludes with practical selection guidelines for network administrators and polytechnic-level networking laboratories, and identifies directions for extending the analysis to physical hardware testbeds and higher VLAN counts.

Introduction

This paper compares two widely used inter-VLAN routing architectures—Router-on-a-Stick (RoAS) and Switched Virtual Interfaces (SVIs)—to determine their performance, scalability, and suitability for different network environments. While VLANs improve network security and reduce broadcast traffic by creating separate logical networks, communication between VLANs requires a Layer 3 routing device. The choice of routing architecture significantly affects network performance, cost, and scalability.

The study reviews the principles of VLAN segmentation and explains that:

• Router-on-a-Stick (RoAS) uses a single trunk connection between a switch and a router with multiple sub-interfaces, making it simple and inexpensive but limited by the shared trunk link and software-based routing.
• Switched Virtual Interfaces (SVIs) perform routing directly inside a Layer 3 switch using dedicated hardware (ASICs), resulting in much higher throughput, lower latency, and better scalability.

A simulation-based methodology is proposed using GNS3/EVE-NG (with Cisco Packet Tracer for configuration verification) to compare the two approaches. The experimental setup includes four VLANs (Administration, Faculty, Student Laboratory, and Server), with performance measured under light, moderate, and heavy traffic conditions. The evaluation metrics include:

• Throughput
• Latency
• Jitter
• Packet loss
• Scalability
• Cost and configuration complexity

Based on previous studies and architectural analysis, the expected results indicate that SVI-based routing consistently outperforms Router-on-a-Stick, especially under moderate and heavy network loads. SVI provides:

• Higher throughput through hardware-based wire-speed routing.
• Lower latency and jitter because packets remain within the Layer 3 switch.
• Better scalability for networks with many VLANs and high traffic volumes.
• Reduced packet loss under heavy load.

In contrast, Router-on-a-Stick remains a practical solution for small networks, branch offices, and educational laboratories due to its lower hardware cost and simpler configuration. It also offers a slight security advantage by routing traffic through an external device that can provide additional inspection and access control.

The paper recommends:

• Router-on-a-Stick for networks with fewer than ten VLANs, light to moderate traffic, limited budgets, and teaching environments.
• SVI routing for enterprise or campus networks requiring high performance, low latency, scalability, and support for many VLANs.
• A hybrid approach, where SVIs handle routine inter-VLAN routing while a dedicated router or firewall provides advanced security inspection.

The study concludes that SVI-based routing is the preferred solution for modern enterprise networks because of its superior performance and scalability, whereas Router-on-a-Stick remains valuable for smaller, cost-sensitive deployments. Future work proposes validating the simulation methodology with real hardware and extending the analysis to larger VLAN deployments, mixed traffic types (such as VoIP and video), and more detailed security evaluations.

Conclusion

This paper has reviewed the architectural principles of VLAN segmentation and inter-VLAN routing, and has developed a structured, simulation-based methodology for comparing Router-on-a-Stick and Switched Virtual Interface routing across throughput, latency, jitter, packet loss, scalability, and cost. Consistent with prior comparative literature, the analysis indicates that SVI-based routing on a Layer 3 switch offers substantially better performance than Router-on-a-Stick, particularly under moderate-to-heavy traffic load, while Router-on-a-Stick retains value for small networks and cost-constrained or teaching environments. This study\'s benchmark figures are drawn from the architecture\'s known characteristics and from previously published simulation results rather than from new experimental data collected for this paper. Future work should execute the proposed test methodology on a physical GNS3/EVE-NG or hardware testbed to generate original throughput, latency, jitter, and packet-loss measurements for verification, extend the comparison to larger VLAN counts and mixed traffic types (including VoIP and video), and evaluate the security implications of each architecture using penetration-testing techniques rather than qualitative assessment alone.

References

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Copyright

Copyright © 2026 Prof. Sunil Bhimrao Dabhade. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.