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Architecture

This section explains the design decisions and technical architecture of the OpenWrt mesh network.

Overview

The mesh network is built on these core technologies:

Technology Purpose Why We Chose It
Batman-adv V Layer 2 mesh routing Protocol-agnostic, BLA for loop prevention, multi-interface
OpenWrt 24.10 Router operating system Open source, extensive package support, active community
TP-Link TL-SG108E Managed switches VLAN trunking, 802.1Q support, affordable
Ansible Configuration management Agentless, idempotent, human-readable

Section Contents

Document Description
Architecture Overview Complete technical deep-dive into the mesh design
Batman-adv Protocol How the mesh routing protocol works
Network Topology Physical and logical network structure
VLAN Architecture Network segmentation design
Switch Integration Managed switch configuration

High-Level Architecture

                    ┌─────────────────────────────────────┐
                    │           INTERNET                  │
                    └───────┬───────────┬───────────┬─────┘
                            │           │           │
                       ┌────┴────┐ ┌────┴────┐ ┌────┴────┐
                       │  WAN 1  │ │  WAN 2  │ │  WAN 3  │
                       │ Node 1  │ │ Node 2  │ │ Node 3  │
                       │10.11.12.1│10.11.12.2│10.11.12.3│
                       └────┬────┘ └────┬────┘ └────┬────┘
                       LAN3 │ LAN4 LAN3 │ LAN4 LAN3 │ LAN4
                            │           │           │
                       ┌────┴───────────┴───────────┴────┐
                       │     Switch A (All VLANs)        │
                       │  + Switch C (Mesh VLAN only)    │
                       │  + 2.4GHz Wireless Backup       │
                       └─────────────────────────────────┘
                                        │
        ┌───────────────────────────────┼───────────────────────────────┐
        │                               │                               │
   ┌────▼────┐                    ┌─────▼────┐                   ┌──────▼────┐
   │  5GHz   │                    │  5GHz    │                   │  5GHz     │
   │ HA-Client│                   │ HA-Client│                   │ HA-Client │
   │(802.11r)│                    │(802.11r) │                   │(802.11r)  │
   └─────────┘                    └──────────┘                   └───────────┘

VLAN Segmentation:

VLAN Network Subnet Purpose
200 Client 10.11.12.0/24 Main LAN, trusted devices
10 Management 10.11.10.0/24 Admin access, switches
20 Guest 10.11.20.0/24 Isolated guest WiFi
30 IoT 10.11.30.0/24 Smart home devices
100 Mesh - Batman-adv backbone

Key Design Decisions

Why Ring Topology?

  • Redundancy: Any single link failure doesn't partition the network
  • Low Latency: Maximum 2 hops between any two nodes
  • Simple Wiring: Only 3 cables needed for full mesh

Why Multi-Gateway?

  • No Single Point of Failure: Each node has its own WAN connection
  • Load Distribution: Clients automatically select best gateway
  • Bandwidth Aggregation: Total bandwidth = sum of all WANs

Why VLAN Segmentation?

  • Security: IoT devices isolated from main network
  • Management: Dedicated management network for switches and nodes
  • Flexibility: Easy to add new network segments

Why Bridge Loop Avoidance (BLA)?

  • Loop Prevention: Switches + mesh create L2 loop potential
  • High Availability: All nodes bridge switch VLANs (no SPOF)
  • Critical Requirement: Node interfaces MUST use static IPs (BLA doesn't protect node-originated DHCP)