Docker Networking Deep Dive

Summary

A service needed a real LAN IP (bypassing Docker bridge's default NAT) so internal IoT devices could reach it directly, so bridge, overlay, macvlan, and host networking modes were surveyed to find the right fit.

System Context

• •Docker Engine 26.x on Ubuntu 22.04, single host (no Swarm/K8s yet)
• •Internal LAN: 192.168.1.0/24, with its own DHCP range for macvlan
• •Compared 4 modes: bridge, overlay, macvlan, host

Checklist

• ☑Macvlan container receives a real LAN IP, reachable by ping from another device
• ☑Compared throughput: host network vs bridge network (iperf3)
• ☑Overlay network works correctly between 2 Docker hosts via Swarm
• ☑Confirmed host mode doesn't conflict with other services' ports on the machine

Commands

docker network create --driver bridge app-net

docker network create -d overlay --attachable mesh-net

docker run --network host nginx

docker network inspect app-net

Conclusion

Bridge networks suffice for single-host development. Overlay networks are essential for Swarm multi-host communication. Macvlan is useful when containers need direct LAN IP addresses. Host networking eliminates NAT overhead for high-performance workloads.