Virtual LAN

Virtual LAN
Michel Bakni · CC BY-SA 4.0 · source
Name	Virtual LAN
Caption	Network diagram illustrating VLAN segmentation
Introduced	1990s
Type	Networking technology
Standard	IEEE 802.1Q

Virtual LAN

Virtual LAN is a network segmentation technology that creates logically separated broadcast domains on shared physical infrastructure. It appears in enterprise Cisco Systems deployments, Juniper Networks fabrics, Dell EMC datacenters, and service-provider environments such as AT&T and Verizon Wireless to isolate traffic for compliance, tenancy, and performance. VLANs integrate with switching products from Hewlett Packard Enterprise and routing platforms from Arista Networks while interoperating with standards bodies like IEEE and management frameworks from IETF and SNIA.

Overview

VLANs implement layer-2 segmentation in switched networks manufactured by vendors including Cisco Systems, IBM, Extreme Networks, Huawei Technologies, and Brocade. Administrators in organizations such as Walmart, Bank of America, University of Oxford, and NASA use VLANs to separate departments, tenants, research labs, and operational networks. Designs often reference textbooks by authors like Andrew S. Tanenbaum and resources from IEEE 802.1 working groups, and are taught in courses at institutions such as Massachusetts Institute of Technology and Stanford University.

Technology and Operation

VLAN operation relies on Ethernet switching hardware from Cisco Systems and Juniper Networks and on tagging methods standardized by IEEE 802.1Q and extended by vendors including Extreme Networks and Arista Networks. Frames are tagged with 12-bit identifiers (VLAN IDs), a mechanism specified by Institute of Electrical and Electronics Engineers committees, enabling trunk links between switches from Dell EMC and Hewlett Packard Enterprise to carry multiple logical networks. Inter-VLAN routing requires routers or Layer-3 switches from Cisco Systems or virtual routers such as those from VMware and Microsoft Azure to forward traffic between VLANs while preserving isolation policies defined by orchestration tools from Red Hat and Ansible.

Configuration and Management

Configuration of VLANs is performed via command-line interfaces on switches from Cisco Systems, graphical interfaces from Ubiquiti Networks, or centralized controllers from Aruba Networks and Fortinet. Management integrates with directory and identity systems like Active Directory and automation platforms from Puppet Labs, Chef (software), and HashiCorp tools; monitoring employs solutions from SolarWinds, Nagios, and Splunk. Policies are often versioned in repositories similar to practices at GitHub and audited under compliance frameworks used by ISO and PCI SSC.

Security and Isolation

Security models for VLANs include access control lists on switches from Cisco Systems and Juniper Networks, 802.1X port-based authentication developed with contributors like Microsoft and Oracle Corporation, and integration with identity providers such as Okta and Ping Identity. Threats mitigated include VLAN hopping incidents analyzed by researchers from SANS Institute and mitigations recommended by groups like CISA; additional isolation arises from overlay technologies by VMware and NVIDIA (formerly Mellanox Technologies). Network segmentation using VLANs supports regulatory regimes enforced by GDPR, HIPAA, and Sarbanes–Oxley Act standards.

Performance and Scalability

Scalability considerations encompass VLAN ID limits (4094 usable IDs) defined in IEEE 802.1Q, aggregation technologies such as link aggregation standardized by IEEE 802.3ad and proprietary stacking from Cisco Systems and HPE Aruba. High-performance switching for low-latency environments is provided by vendors like Arista Networks and Juniper Networks, and is benchmarked in labs at ETSI and research at CERN. Large-scale multitenant fabrics use virtualization and overlay protocols to circumvent VLAN limits, leveraging platforms from VMware, OpenStack Foundation, and cloud providers Amazon Web Services and Google Cloud Platform.

Standards and Protocols

Key standards include IEEE 802.1Q for tagging, IEEE 802.1ad (Q-in-Q) for provider bridging, and IEEE 802.1X for port authentication; control-plane protocols such as VTP (vendor-specific), GVRP, and integration with LACP for aggregated links are widely used. Interoperability testing is performed at events hosted by IETF and Unix Network Programming communities; best practices reference documentation from IEEE working groups and vendor interoperability matrices provided by Cisco Systems and Juniper Networks.

Use Cases and Deployment scenarios

Common deployments include enterprise campus networks at corporations like Siemens, multitenant cloud datacenters run by Equinix and Digital Realty, service-provider metro-Ethernet offerings from AT&T and Verizon Communications, and virtualized overlays in environments operated by VMware and Microsoft Azure. VLANs are used to segregate voice traffic for systems from Avaya and Polycom, isolate storage networks interoperating with EMC Corporation and NetApp, and partition lab and research networks at institutions such as Harvard University and University of Cambridge.

Category:Computer networking