@@ -162,10 +162,6 @@ func detachMounted(path string) error {

 	return nil

 }

-func getDefaultRouteMtu() (int, error) {

-	return -1, errSystemNotSupported

-}

-

 func killProcessDirectly(container *container.Container) error {

 	return nil

 }

@@ -1382,13 +1382,8 @@ func setDefaultMtu(config *Config) {

 		return

 	}

 	config.Mtu = defaultNetworkMtu

-	if routeMtu, err := getDefaultRouteMtu(); err == nil {

-		config.Mtu = routeMtu

-	}

 }

-var errNoDefaultRoute = errors.New("no default route was found")

-

 // verifyContainerSettings performs validation of the hostconfig and config

 // structures.

 func (daemon *Daemon) verifyContainerSettings(hostConfig *runconfig.HostConfig, config *runconfig.Config) ([]string, error) {

@@ -33,7 +33,6 @@ import (

 	"github.com/docker/libnetwork/types"

 	blkiodev "github.com/opencontainers/runc/libcontainer/configs"

 	"github.com/opencontainers/runc/libcontainer/label"

-	"github.com/vishvananda/netlink"

 )

 const (

@@ -670,25 +669,6 @@ func (daemon *Daemon) conditionalUnmountOnCleanup(container *container.Container

 	daemon.Unmount(container)

 }

-// getDefaultRouteMtu returns the MTU for the default route's interface.

-func getDefaultRouteMtu() (int, error) {

-	routes, err := netlink.RouteList(nil, 0)

-	if err != nil {

-		return 0, err

-	}

-	for _, r := range routes {

-		// a nil Dst means that this is the default route.

-		if r.Dst == nil {

-			i, err := net.InterfaceByIndex(r.LinkIndex)

-			if err != nil {

-				continue

-			}

-			return i.MTU, nil

-		}

-	}

-	return 0, errNoDefaultRoute

-}

-

 func restoreCustomImage(driver graphdriver.Driver, is image.Store, ls layer.Store, ts tag.Store) error {

 	// Unix has no custom images to register

 	return nil

@@ -16,7 +16,7 @@ The information in this section explains how to customize the Docker default bri

 By default, the Docker server creates and configures the host system's `docker0` interface as an _Ethernet bridge_ inside the Linux kernel that can pass packets back and forth between other physical or virtual network interfaces so that they behave as a single Ethernet network.

-Docker configures `docker0` with an IP address, netmask and IP allocation range. The host machine can both receive and send packets to containers connected to the bridge, and gives it an MTU -- the _maximum transmission unit_ or largest packet length that the interface will allow -- of either 1,500 bytes or else a more specific value copied from the Docker host's interface that supports its default route.  These options are configurable at server startup:

+Docker configures `docker0` with an IP address, netmask and IP allocation range. The host machine can both receive and send packets to containers connected to the bridge, and gives it an MTU -- the _maximum transmission unit_ or largest packet length that the interface will allow -- of 1,500 bytes. These options are configurable at server startup:

 - `--bip=CIDR` -- supply a specific IP address and netmask for the `docker0` bridge, using standard CIDR notation like `192.168.1.5/24`.

 - `--fixed-cidr=CIDR` -- restrict the IP range from the `docker0` subnet, using the standard CIDR notation like `172.167.1.0/28`. This range must be an IPv4 range for fixed IPs (ex: 10.20.0.0/16) and must be a subset of the bridge IP range (`docker0` or set using `--bridge`). For example with `--fixed-cidr=192.168.1.0/25`, IPs for your containers will be chosen from the first half of `192.168.1.0/24` subnet.