Meaning of abbreviation "docker_gwbridge" or what does "GW" actually mean?

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I'm new to networking and I'm trying to figure out the different abbreviation in order to get a better understanding and obviously I'm involved in docker currently. I was wondering what does "GW" in "docker_gwbridge" actually mean?

docker networking
1 Answers

From this issue and because it's defined in the file default_gateway_linux.go, it appears that gw means gateway. "Gateway" is also mentioned several times in the docs for docker_gwbridge. A network gateway is provides interoperability between two networks and contains devices to translate between each end of the network. In Docker's case, this is used to allow multiple Docker daemons to interact in a swarm by linking their network layer to allow containers running on different hosts to communicate over the network.

Use Case

From the docs: The docker_gwbridge is a virtual bridge that connects the overlay networks (including the ingress network) to an individual Docker daemon’s physical network.

The reason this virtual bridge exists is to be an entrypoint to connect Docker daemons to the networking layer of an individual Docker daemon host. Again from the docs, an ingress and a docker_gwbridge are created when starting Docker by default. A possible use case for a docker_gwbridge is to manually specify the subnet of an existing bridge network from another Docker daemon.

Example

From the docs, this is how that would work:

  1. Stop Docker.

  2. Delete the existing docker_gwbridge interface.

$ sudo ip link set docker_gwbridge down
$ sudo ip link del dev docker_gwbridge
  1. Start Docker. Do not join or initialize the swarm.
  2. Create or re-create the docker_gwbridge bridge manually with your custom settings, using the docker network create command. This example uses the subnet 10.11.0.0/16. For a full list of customizable options, see Bridge driver options.
$ docker network create \
    --subnet 10.11.0.0/16 \
    --opt com.docker.network.bridge.name=docker_gwbridge \
    --opt com.docker.network.bridge.enable_icc=false \
    --opt com.docker.network.bridge.enable_ip_masquerade=true \
    docker_gwbridge
  1. Initialize or join the swarm. Since the bridge already exists, Docker does not create it with automatic settings.
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