7.1.1.4 Bridge Connectivity Path
A focused guide to Bridge Connectivity Path, connecting core concepts with practical Docker and container operations.
The bridge connectivity path is the complete route network traffic takes between a container and the outside world (or another container), passing through the container's veth pair, the host's bridge interface, and ultimately the host's own network stack or another container's corresponding veth pair.
Tracing the Path Between Two Containers
When two containers on the same bridge network communicate, traffic flows from one container's network namespace, through its veth pair, across the shared bridge, and through the destination container's own veth pair into its namespace.
docker network create mynet
docker run -d --name container-a --network mynet alpine sleep 1000
docker run -d --name container-b --network mynet alpine sleep 1000
docker exec container-a ping container-b
This traffic traverses the full bridge connectivity path between the two containers' separate network namespaces.
Tracing the Path for External Connectivity
When a container communicates with the external internet, its traffic flows through this same bridge path, then through the host's own networking stack (typically via NAT) before reaching the broader network.
docker exec container-a ping 8.8.8.8
Tracing the Path for a Published Port
When external traffic reaches a published port, it flows from the host's network interface, through Docker's configured port forwarding rules, across the bridge, and into the target container's namespace via its veth pair.
docker run -d -p 8080:80 nginx:alpine
curl http://localhost:8080
Why Understanding the Connectivity Path Matters
Tracing the complete path traffic takes — through veth pairs, the bridge, and the host's own networking — provides a clear mental model for diagnosing connectivity issues at the specific point along this path where something might actually be going wrong, rather than treating container networking as an opaque black box.
docker network inspect mynet
This reveals the bridge network's configuration, useful context when tracing exactly how traffic is expected to flow along this path.