Logical WAN Interface Assignment

Problem

Physical WAN NICs alone are too rigid for multi-ISP sites. Customers need logical WAN ports that can map dynamically to physical links, support extra WAN paths (tertiary/quaternary), and fail over IPsec tunnels without long outages.

How it works

• A logical WAN layer sits above physical NICs: each logical interface (e.g. primary/secondary/additional WAN) can be mapped to a real Ethernet device.
• Configuration and bootstrap paths bring interfaces up, apply addressing, and wire iptables/routing as the mapping changes.
• IPsec tunnels bind to the active logical WAN path; when a link fails, automated failover moves tunnels to a healthy path.
• Dynamic port/path changes are handled so sites with multiple ISPs stay connected with lower disruption and latency impact.

What I built / owned

• Designed and implemented the C/C++ logical-to-physical WAN mapping layer with NIC management.
• Added support for tertiary and quaternary WAN connectivity beyond the classic dual-WAN model.
• Integrated dynamic iptables and bootstrap configuration handling for tunnel stability and multi-ISP failover.

Impact

Sites gain flexible multi-ISP WAN topologies with automated IPsec failover, improving resilience and reducing manual reconfiguration when links or ports change.

Tech

C/C++ · Linux netlink / interfaces · IPsec / StrongSwan · iptables · ANAP control plane