Advanced Networking

Synopsis #

This section presents advanced configuration patterns for building and operating complex OpenBSD networks. It focuses on high availability, multi-homing, tunneling, IPv6 at scale, quality of service, MPLS, large-scale network services, virtualization-aware designs, L2/L3 architecture, telemetry, hardening, reference topologies, and troubleshooting playbooks. Each chapter provides concise design guidance, annotated configurations, verification steps, and operator-focused troubleshooting procedures.

Relation to “Networking” and “OpenBGPD” #

The Networking section covers foundational interfaces, routing, and packet filtering concepts suitable for most single-host or small deployments. Advanced Networking builds on those foundations to address redundancy, scale, and operational safety across larger environments.

The OpenBGPD section focuses on external and internal BGP policy, peering, and route distribution. Where appropriate, this section references BGP as a control plane input (for example, anycast services or MPLS VPNs), but defers detailed BGP policy and session management to the dedicated OpenBGPD chapter at /openbgpd.

Contents #

The following chapters are ordered for incremental complexity. Each item links to its chapter and includes a one-line summary.

• High Availability and State Replication — Redundant gateways and firewalls using CARP, pfsync, relayd, and event-driven failover.
• Multi-WAN and Policy-Based Routing — Route-to, reply-to, monitoring, and inbound considerations for multi-provider edges.
• VPN and Cryptographic Tunneling — IKEv2 with iked, WireGuard-style tunnels, NAT traversal, and performance tuning.
• Classic and Lightweight Tunnels — gif, gre, and etherip for pragmatic overlays and migrations.
• IPv6 at Scale — Router Advertisements, ND, prefix delegation, NPTv6, and large-segment IPv6 operations.
• QoS and Traffic Shaping — Classification and queuing with PF for latency-sensitive and bulk traffic.
• MPLS and Label Distribution — mpls(4) data plane with LDP via ldpd, PE interfaces (mpe), and L2 VPLS pseudowires.
• Network Services at Scale — Authoritative DNS with nsd, validating recursion with unbound, DHCP roles, and time services.
• Virtualization and Host Networking — vmd, tap/vether, bridging/VLANs, and micro-segmentation with PF anchors.
• Large-Scale L2 and L3 Design — VLAN strategy, routed access, first-hop redundancy, and anycast service placement.
• Telemetry, Logging, and Flow Export — pflog analysis, pflow (NetFlow/IPFIX), snmpd, and time-series integration.
• Hardening and Operational Safety — Anti-spoofing, RPF, secrets management, and safe rollout procedures.
• Reference Architectures — End-to-end designs: redundant Internet edge, campus/branch, and POP patterns.
• Troubleshooting Playbooks — Diagnosing HA flips, asymmetric paths, tunnel MTU issues, IPv6 ND, and QoS verification.

How to Use This Section #

1. Read chapters in order on a first pass to establish common patterns and terminology.
2. For implementation, jump directly to the relevant chapter based on your objective (for example, HA, IPv6, or QoS).
3. Apply the Design Considerations before touching configuration.
4. Use the Verification steps immediately after deployment to confirm behavior.
5. Keep the Troubleshooting playbooks nearby during rollouts and incident response.

Next Steps #

Proceed to High Availability and State Replication , then continue through the chapters in order for a complete tour. You can also jump directly to the chapter that matches your current task.