What is the difference between Docker overlay and bridge networks

· Category: DevOps & Docker

Short answer

Bridge networks connect containers on a single Docker host, while overlay networks span multiple hosts in a Docker Swarm or Kubernetes cluster, enabling cross-node service discovery.

Details

The default bridge network isolates containers on one machine and supports custom user-defined bridges for DNS resolution between containers. When you move to multi-host orchestration, overlay networks use VXLAN encapsulation to create a virtual subnet across nodes. Proper network segmentation requires understanding CIDR notation so you can allocate IP pools without overlap. In production, define overlay networks in Docker Compose files or Swarm stacks, and restrict traffic with encrypted control planes. For local development, user-defined bridge networks usually suffice and are simpler to debug.

Tips

  • Enable encryption on overlay networks with --opt encrypted for sensitive multi-host traffic.
  • Avoid the default bridge for production; it lacks automatic DNS and manual link management.
  • Monitor overlay network latency if your cluster spans multiple availability zones.