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configuring-network-segmentation-with-vlans

Configures VLAN-based network segmentation on managed switches with hardening and inter-VLAN access control.

954|172|Updated Mar 13, 2026
Search Tags:#network security#VLAN#network segmentation#802.1q#switch hardening#dhcp snooping#access control lists
One-click install
npx skills add https://github.com/xalgord/xalgorix --skill configuring-network-segmentation-with-vlans
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: configuring-network-segmentation-with-vlans
Source: https://github.com/xalgord/xalgorix/tree/main/internal/tools/skills/data/network-security/configuring-network-segmentation-with-vlans
Command: npx skills add https://github.com/xalgord/xalgorix --skill configuring-network-segmentation-with-vlans

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Flat enterprise networks allow unrestricted lateral movement, letting a single compromised host reach sensitive systems like payment terminals or servers. This Skill guides the design and implementation of VLAN-based segmentation on managed switches so network zones are isolated and traffic between them is explicitly controlled.

Core Features & Use Cases

  • VLAN Architecture Design: Defines security zones (corporate, servers, DMZ, guest, IoT, management, quarantine) with subnets and a traffic flow matrix.
  • Switch Hardening: Disables DTP, sets an unused native VLAN, and enables DHCP snooping, Dynamic ARP Inspection, IP Source Guard, port security, and BPDU guard to prevent VLAN hopping.
  • Inter-VLAN Access Control: Configures SVIs and extended ACLs on a Layer 3 switch or firewall, plus per-VLAN DHCP pools.
  • Use Case: A retail chain must isolate POS terminals for PCI-DSS compliance; the Skill produces a CDE VLAN reachable only by the payment processor on port 443, verified by cross-VLAN ping tests that must fail.

Quick Start

Ask the AI to design and configure VLAN segmentation for your network, including switch hardening commands and inter-VLAN ACLs for your switch platform.

Frequently Asked Questions about configuring-network-segmentation-with-vlans

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I configure VLAN segmentation on Cisco switches?▼

Create named VLANs, assign access ports with switchport mode access and switchport nonegotiate, and configure trunks with an unused native VLAN and explicit allowed VLAN lists. Then add SVIs and ACLs on a Layer 3 switch for controlled inter-VLAN routing.

How to prevent VLAN hopping attacks on a network?▼

Disable DTP with switchport nonegotiate on all ports, set the native VLAN to an unused ID like 998 on every trunk, and avoid VLAN 1. Enable DHCP snooping, Dynamic ARP Inspection, and IP Source Guard to block spoofing-based hops.

Does VLAN segmentation alone meet PCI-DSS requirements?▼

No, VLANs must be combined with Layer 3 filtering such as ACLs or firewall rules restricting CDE traffic to specific hosts and ports. The Skill explicitly warns against using VLANs as the sole security control without inter-VLAN access control.

Why is my inter-VLAN traffic still passing after applying ACLs?▼

ACLs may be applied in the wrong direction on the VLAN interface or lack a terminating deny ip any any log statement. Verify hit counts with show ip access-lists and run negative tests like cross-VLAN pings, which must fail.

When should VLANs not be used for network isolation?▼

VLANs are unsuitable as the sole control for networks requiring air-gapping or when switches are not hardened against VLAN hopping. High-assurance isolation of critical systems demands physical separation or dedicated firewalls instead.

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