Trunking

Overview

Trunking is a network security tool that appears across network security workflows in this knowledge base. It is referenced as part of higher-level security analysis, investigation, monitoring, or validation activity rather than as an end in itself.

What It Is

Trunking is best understood as a network-security tool in this knowledge base. Its role is conceptual and system-facing rather than procedural: it gives analysts or defenders a structured way to examine evidence, model system behavior, or reason about security state.

How It Works

Trunking works by turning technical inputs into more interpretable outputs at the system level. Across the source skills, it appears as part of larger analysis, investigation, monitoring, or validation loops rather than as a standalone end state.

Core Concepts

• network security
• vlan
• network segmentation
• switch security
• 802.1q

Typical Workflow

• VLAN 10 - CORPORATE (10.10.10.0/24) - Employee workstations
• VLAN 20 - SERVERS (10.10.20.0/24) - Internal servers
• VLAN 30 - DMZ (10.10.30.0/24) - Internet-facing servers
• VLAN 40 - GUEST (10.10.40.0/24) - Guest WiFi
• VLAN 50 - IOT (10.10.50.0/24) - IoT/OT devices
• VLAN 60 - VOIP (10.10.60.0/24) - VoIP phones
• VLAN 100 - MANAGEMENT (10.10.100.0/24) - Switch/AP management
• VLAN 999 - QUARANTINE (10.10.99.0/24) - Isolated/compromised hosts
• VLAN 998 - NATIVE_UNUSED - Native VLAN (no traffic)

Use Cases

• Segmenting an enterprise network into isolated security zones (corporate, servers, DMZ, guest, IoT)
• Meeting compliance requirements (PCI-DSS, HIPAA, SOC 2) that mandate network isolation for sensitive data
• Reducing blast radius of security incidents by preventing lateral movement between network segments
• Isolating high-risk devices (IoT, BYOD, legacy systems) from critical infrastructure
• Implementing defense-in-depth by combining VLANs with firewall rules and access control lists
• Leaving DTP enabled on access ports, allowing VLAN hopping to reach the CDE
• Using VLAN 1 as the native VLAN, enabling double-tagging attacks

Limitations

• Output still depends on context, data quality, and surrounding analysis.
• The tool should be interpreted as part of a broader workflow, not as a complete answer by itself.
• Capabilities and visibility vary depending on environment, integrations, and available inputs.

Related Tools

• And Network Topology, And Security Feature Support, Cisco Catalyst, HP Aruba CX, IP Addressing, NetBox, Nmap, PfSense

Sources

• configuring-network-segmentation-with-vlans