@@ -49,7 +49,7 @@ func DaemonConfigFromJob(job *engine.Job) *DaemonConfig {

 	if mtu := job.GetenvInt("Mtu"); mtu != 0 {

 		config.Mtu = mtu

 	} else {

-		config.Mtu = DefaultNetworkMtu

+		config.Mtu = GetDefaultNetworkMtu()

 	}

 	config.DisableNetwork = job.Getenv("BridgeIface") == DisableNetworkBridge

@@ -43,7 +43,7 @@ func main() {

 		flInterContainerComm = flag.Bool([]string{"#icc", "-icc"}, true, "Enable inter-container communication")

 		flGraphDriver        = flag.String([]string{"s", "-storage-driver"}, "", "Force the docker runtime to use a specific storage driver")

 		flHosts              = docker.NewListOpts(docker.ValidateHost)

-		flMtu                = flag.Int([]string{"#mtu", "-mtu"}, docker.GetDefaultNetworkMtu(), "Set the containers network mtu")

+		flMtu                = flag.Int([]string{"#mtu", "-mtu"}, 0, "Set the containers network MTU; if no value is provided: default to the default route MTU or 1500 if not default route is available")

 	)

 	flag.Var(&flDns, []string{"#dns", "-dns"}, "Force docker to use specific DNS servers")

 	flag.Var(&flHosts, []string{"H", "-host"}, "tcp://host:port, unix://path/to/socket, fd://* or fd://socketfd to use in daemon mode. Multiple sockets can be specified")

@@ -4,9 +4,6 @@ import (

 	"archive/tar"

 	"bytes"

 	"fmt"

-	"github.com/dotcloud/docker"

-	"github.com/dotcloud/docker/engine"

-	"github.com/dotcloud/docker/utils"

 	"io"

 	"io/ioutil"

 	"net/http"

@@ -16,6 +13,10 @@ import (

 	"strings"

 	"testing"

 	"time"

+

+	"github.com/dotcloud/docker"

+	"github.com/dotcloud/docker/engine"

+	"github.com/dotcloud/docker/utils"

 )

 // This file contains utility functions for docker's unit test suite.

@@ -32,7 +33,7 @@ func mkRuntime(f utils.Fataler) *docker.Runtime {

 	config := &docker.DaemonConfig{

 		Root:        root,

 		AutoRestart: false,

-		Mtu:         docker.DefaultNetworkMtu,

+		Mtu:         docker.GetDefaultNetworkMtu(),

 	}

 	eng, err := engine.New(root)