L3 Segmentation vs L2 VLANs
Introduction
Since the introduction of VLANs (802.1q), networks have become increasingly complex. Cloud adoption, IoT proliferation, and heightened security needs have exposed the limitations of traditional Layer 2 segmentation approaches.
Broadcast domain limitations, complex management overhead, and insufficient security boundaries hinder scalability, agility, and the ability to enforce granular access controls.
This document explores how dynamic, policy driven Layer 3 segmentation, a foundational innovation of the Nile Access Service (NaaS), addresses these challenges, enabling organizations to build secure, dynamic, and future-proof networks.
Shiv> One key concept we are trying to drive towards is zero trust should not be based on IP's. VLANs were invented to limit broadcast storms and hence limit number of devices in a VLAN. They got misused as a security tool where people started using it for segmentation. So we should differentiate between segments and segmentation ideally. In our world devices on the same subnet a.k.a are also segmented. We did segments so we can fit in the current model of VLANs as customers think that way. But with our new micro-segmentation (phase 1 will be out soon) our north star is one large subnet and all users and devices in that subnet. We will do segmentation based on Users, devices and apps as opposed to IP's. Customers may not adopt this but that is what we will recommend.
Everything i mentioned above will be part of the zero trust page but I wanted to point it out here so that we don't present segments as segmentation e.g. I would say "What is a Layer 3 only network?" as opposed to What is Layer 3 Segmentation?". We can chat if you prefer.
What is Layer 3 Segmentation?
Layer 3 segmentation in the Nile Access Service is an approach to logically dividing a network into secure, isolated segments at the network layer (Layer 3) of the OSI model. It leverages hybrid cloud technologies, dedicated Nile Access Service hardware, and OSPF routing to create logical subnets that can span across multiple physical networks and locations Shiv> If i understand your statement correctly are you saying a subnet spans locations? If so, that is not correct. The segment name like Employee can span locations but for each location there is usually a unique subnet unless they plan to use NAT at every site and use the same subnet. Layer 3 segmentation also solves the inherent complexity of managing and securing traditional VLANs, as segments are created in the Nile Customer Portal and applied to devices and users wherever they connect.
Unlike traditional VLANs, which operate at the data link layer (Layer 2) and are confined to broadcast domains, Layer 3 segmentation transcends these limitations by separating the logical network topology from the underlying physical infrastructure. This separation enables greater flexibility, scalability, and enhanced security compared to VLAN-based segmentation methods.
Key advantages of Nile's Layer 3 segmentation include:
- Scalability: Layer 3 segmentation can accommodate a large number of logical segments without the limitations of broadcast domains or VLAN ID exhaustion, making it suitable for large-scale deployments, multiple geographic locations, or a hybrid.
- Security: By default, each segment, device and user is isolated from all others, mitigating the spread of threats and reducing the attack surface. For instance, unkown devices accessing the network are isolated by default, mitigating any threat of malware entering the domain. Layer 3 segmentation is fundamental to Nile's Zero Trust Campus.
- Flexibility: Logical segments can be created, modified, or removed dynamically, independent of the underlying physical network infrastructure, enabling agile and responsive network management.
- Centralized Management: Layer 3 segmentation by Nile delivers centralized management and policy enforcement, simplifying the configuration and administration of network segmentation across distributed environments.
- Location Independence: Network access and connectivity are no longer tied to physical locations or switch ports. Instead, users and devices can be assigned to logical segments based on policies, identities, or application requirements, enabling secure access from anywhere. For example; a college faculty member will often connect their laptop via Ethernet and Wi-Fi at multiple locations across the campus. Regardless of port o used or location, they will be automatically placed in their faculty segment. If a student plugged into that same port vacated by the faculty member, they would automatically join the student segment.
Layer 3 segmentation in the Nile Service Block operates at the network layer by leveraging OSPF to facilitate communication between segments. Each segment functions as a separate logical subnet or virtual network, with upstream security appliances or routers handling inter-segment traffic. The Nile Access Service integrates closely with security vendors like Palo Alto, Fortinet and zScaler, ensuring policies are consistently applied to all traffic.
This approach enables organizations to implement granular access controls, microsegmentation, and continuous authentication and authorization, aligning with our principles of the zero-trust campus and enhancing overall network security posture.
Layer 2 vs Layer 3
| Characteristic | VLAN (Layer 2) | Layer 3 Segmentation |
|---|---|---|
| Scope of Segmentation | Confined to the broadcast domain | Creates logical subnets isolated at the network layer |
| Role of Routing | Requires external routers for inter-VLAN communication | Inherently leverages routing for inter-segment traffic |
| Configuration Complexity | Accelerating configuration overhead across multiple devices and vendors | Centralized configuration enabling granular, policy-based enforcement aligned with zero-trust principles |
| Security Vulnerabilities | Susceptible to attacks within shared broadcast domains and at the physical port layer. |
Default isolation between segments, users and devices, mitigating the spread of threats |
| Redundant Connectivity | Implementing redundant links is cumbersome | OSPF routing enables optimized path selection |
| Broadcast Domain Issues | Prone to broadcast storms and performance degradation in large networks | Significantly reduces broadcast traffic, enhancing performance |
| Connectivity Approach | Often tied to physical location or switch port | Enables policy-based connectivity based on user identity, device type, or application |
The dynamic Layer 3 segmentation provided by the Nile Access Service, provides a robust foundation for implementing zero-trust architectures. This is due to its ability to enable granular network microsegmentation, policy-driven access controls, and continuous authentication and authorization.