# network create ```markdown Usage: docker network create [OPTIONS] Create a network Options: --aux-address value Auxiliary IPv4 or IPv6 addresses used by Network driver (default map[]) -d, --driver string Driver to manage the Network (default "bridge") --gateway value IPv4 or IPv6 Gateway for the master subnet (default []) --help Print usage --internal Restrict external access to the network --ip-range value Allocate container ip from a sub-range (default []) --ipam-driver string IP Address Management Driver (default "default") --ipam-opt value Set IPAM driver specific options (default map[]) --ipv6 Enable IPv6 networking --label value Set metadata on a network (default []) -o, --opt value Set driver specific options (default map[]) --subnet value Subnet in CIDR format that represents a network segment (default []) ``` Creates a new network. The `DRIVER` accepts `bridge` or `overlay` which are the built-in network drivers. If you have installed a third party or your own custom network driver you can specify that `DRIVER` here also. If you don't specify the `--driver` option, the command automatically creates a `bridge` network for you. When you install Docker Engine it creates a `bridge` network automatically. This network corresponds to the `docker0` bridge that Engine has traditionally relied on. When you launch a new container with `docker run` it automatically connects to this bridge network. You cannot remove this default bridge network, but you can create new ones using the `network create` command. ```bash $ docker network create -d bridge my-bridge-network ``` Bridge networks are isolated networks on a single Engine installation. If you want to create a network that spans multiple Docker hosts each running an Engine, you must create an `overlay` network. Unlike `bridge` networks, overlay networks require some pre-existing conditions before you can create one. These conditions are: * Access to a key-value store. Engine supports Consul, Etcd, and ZooKeeper (Distributed store) key-value stores. * A cluster of hosts with connectivity to the key-value store. * A properly configured Engine `daemon` on each host in the cluster. The `dockerd` options that support the `overlay` network are: * `--cluster-store` * `--cluster-store-opt` * `--cluster-advertise` To read more about these options and how to configure them, see ["*Get started with multi-host network*"](../../userguide/networking/get-started-overlay.md). While not required, it is a good idea to install Docker Swarm to manage the cluster that makes up your network. Swarm provides sophisticated discovery and server management tools that can assist your implementation. Once you have prepared the `overlay` network prerequisites you simply choose a Docker host in the cluster and issue the following to create the network: ```bash $ docker network create -d overlay my-multihost-network ``` Network names must be unique. The Docker daemon attempts to identify naming conflicts but this is not guaranteed. It is the user's responsibility to avoid name conflicts. ## Connect containers When you start a container, use the `--network` flag to connect it to a network. This example adds the `busybox` container to the `mynet` network: ```bash $ docker run -itd --network=mynet busybox ``` If you want to add a container to a network after the container is already running, use the `docker network connect` subcommand. You can connect multiple containers to the same network. Once connected, the containers can communicate using only another container's IP address or name. For `overlay` networks or custom plugins that support multi-host connectivity, containers connected to the same multi-host network but launched from different Engines can also communicate in this way. You can disconnect a container from a network using the `docker network disconnect` command. ## Specifying advanced options When you create a network, Engine creates a non-overlapping subnetwork for the network by default. This subnetwork is not a subdivision of an existing network. It is purely for ip-addressing purposes. You can override this default and specify subnetwork values directly using the `--subnet` option. On a `bridge` network you can only create a single subnet: ```bash $ docker network create --driver=bridge --subnet=192.168.0.0/16 br0 ``` Additionally, you also specify the `--gateway` `--ip-range` and `--aux-address` options. ```bash $ docker network create \ --driver=bridge \ --subnet=172.28.0.0/16 \ --ip-range=172.28.5.0/24 \ --gateway=172.28.5.254 \ br0 ``` If you omit the `--gateway` flag the Engine selects one for you from inside a preferred pool. For `overlay` networks and for network driver plugins that support it you can create multiple subnetworks. ```bash $ docker network create -d overlay \ --subnet=192.168.0.0/16 \ --subnet=192.170.0.0/16 \ --gateway=192.168.0.100 \ --gateway=192.170.0.100 \ --ip-range=192.168.1.0/24 \ --aux-address a=192.168.1.5 --aux-address b=192.168.1.6 \ --aux-address a=192.170.1.5 --aux-address b=192.170.1.6 \ my-multihost-network ``` Be sure that your subnetworks do not overlap. If they do, the network create fails and Engine returns an error. # Bridge driver options When creating a custom network, the default network driver (i.e. `bridge`) has additional options that can be passed. The following are those options and the equivalent docker daemon flags used for docker0 bridge: | Option | Equivalent | Description | |--------------------------------------------------|-------------|-------------------------------------------------------| | `com.docker.network.bridge.name` | - | bridge name to be used when creating the Linux bridge | | `com.docker.network.bridge.enable_ip_masquerade` | `--ip-masq` | Enable IP masquerading | | `com.docker.network.bridge.enable_icc` | `--icc` | Enable or Disable Inter Container Connectivity | | `com.docker.network.bridge.host_binding_ipv4` | `--ip` | Default IP when binding container ports | | `com.docker.network.mtu` | `--mtu` | Set the containers network MTU | The following arguments can be passed to `docker network create` for any network driver, again with their approximate equivalents to `docker daemon`. | Argument | Equivalent | Description | |--------------|----------------|--------------------------------------------| | `--gateway` | - | IPv4 or IPv6 Gateway for the master subnet | | `--ip-range` | `--fixed-cidr` | Allocate IPs from a range | | `--internal` | - | Restrict external access to the network | | `--ipv6` | `--ipv6` | Enable IPv6 networking | | `--subnet` | `--bip` | Subnet for network | For example, let's use `-o` or `--opt` options to specify an IP address binding when publishing ports: ```bash $ docker network create \ -o "com.docker.network.bridge.host_binding_ipv4"="172.19.0.1" \ simple-network ``` ### Network internal mode By default, when you connect a container to an `overlay` network, Docker also connects a bridge network to it to provide external connectivity. If you want to create an externally isolated `overlay` network, you can specify the `--internal` option. ## Related information * [network inspect](network_inspect.md) * [network connect](network_connect.md) * [network disconnect](network_disconnect.md) * [network ls](network_ls.md) * [network rm](network_rm.md) * [Understand Docker container networks](../../userguide/networking/index.md)