moby--moby/man/docker-network-create.1.md

% DOCKER(1) Docker User Manuals
% Docker Community
% OCT 2015
# NAME
docker-network-create - create a new network

# SYNOPSIS
**docker network create**

**--aux-address=map[]**    
**-d** | **--driver=DRIVER**       
**--gateway=[]**             
**--help=false**             
**--ip-range=[]**            
**--ipam-driver=default**    
**-o** | **--opt=map[]**           
**--subnet=[]**              

# DESCRIPTION

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 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 `docker daemon` 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*"](https://www.docker.com/engine/userguide/networking/get-started-overlay.md).

It is also a good idea, though not required, that you install Docker Swarm on to
manage the cluster that makes up your network. Swarm provides sophisticated
discovery and server management 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 `--net` flag to connect it to a network.
This adds the `busybox` container to the `mynet` network.

```bash
$ docker run -itd --net=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 the `--subnet` option. On a
`bridge` network you can only create a single subnet:

```bash
docker network create -d --subnet=192.168.0.0/16
```
Additionally, you also specify the `--gateway` `--ip-range` and `--aux-address` options.

```bash
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-newtork
```
Be sure that your subnetworks do not overlap. If they do, the network create fails and Engine returns an error.

# OPTIONS
**--aux-address=map[]**     
  Auxiliary ipv4 or ipv6 addresses used by network driver

**-d** | **--driver=DRIVER**       
  Driver to manage the Network bridge or overlay. The default is bridge.

**--gateway=[] **            
  ipv4 or ipv6 Gateway for the master subnet

**--help=false **            
  Print usage

**--ip-range=[] **           
  Allocate container ip from a sub-range

**--ipam-driver=default **   
  IP Address Management Driver

**-o | --opt=map[]**           
  Set custom network plugin options

**--subnet=[]**              
  Subnet in CIDR format that represents a network segment

# HISTORY
OCT 2015, created by Mary Anthony <mary@docker.com>