@@ -240,7 +240,7 @@ func TestDefaultNetworkOpts(t *testing.T) {

 			// Create a new network

 			networkName := "testnet"

-			network.CreateNoError(ctx, t, c, networkName, func(create *types.NetworkCreate) {

+			networkId := network.CreateNoError(ctx, t, c, networkName, func(create *types.NetworkCreate) {

 				if tc.configFrom {

 					create.ConfigFrom = &ntypes.ConfigReference{

 						Network: "from-net",

@@ -249,6 +249,15 @@ func TestDefaultNetworkOpts(t *testing.T) {

 			})

 			defer c.NetworkRemove(ctx, networkName)

+			// Check the MTU of the bridge itself, before any devices are connected. (The

+			// bridge's MTU will be set to the minimum MTU of anything connected to it, but

+			// it's set explicitly on the bridge anyway - so it doesn't look like the option

+			// was ignored.)

+			cmd := exec.Command("ip", "link", "show", "br-"+networkId[:12])

+			output, err := cmd.CombinedOutput()

+			assert.NilError(t, err)

+			assert.Check(t, is.Contains(string(output), fmt.Sprintf(" mtu %d ", tc.mtu)), "Bridge MTU should have been set to %d", tc.mtu)

+

 			// Start a container to inspect the MTU of its network interface

 			id1 := container.Run(ctx, t, c, container.WithNetworkMode(networkName))

 			defer c.ContainerRemove(ctx, id1, containertypes.RemoveOptions{Force: true})

@@ -735,6 +735,14 @@ func (d *driver) createNetwork(config *networkConfiguration) (err error) {

 		bridgeSetup.queueStep(setupDefaultSysctl)

 	}

+	// Always set the bridge's MTU if specified. This is purely cosmetic; a bridge's

+	// MTU is the min MTU of device connected to it, and MTU will be set on each

+	// 'veth'. But, for a non-default MTU, the bridge's MTU will look wrong until a

+	// container is attached.

+	if config.Mtu > 0 {

+		bridgeSetup.queueStep(setupMTU)

+	}

+

 	// Even if a bridge exists try to setup IPv4.

 	bridgeSetup.queueStep(setupBridgeIPv4)

@@ -45,6 +45,14 @@ func setupDevice(config *networkConfiguration, i *bridgeInterface) error {

 	return nil

 }

+func setupMTU(config *networkConfiguration, i *bridgeInterface) error {

+	if err := i.nlh.LinkSetMTU(i.Link, config.Mtu); err != nil {

+		log.G(context.TODO()).WithError(err).Errorf("Failed to set bridge MTU %s via netlink", config.BridgeName)

+		return err

+	}

+	return nil

+}

+

 func setupDefaultSysctl(config *networkConfiguration, i *bridgeInterface) error {

 	// Disable IPv6 router advertisements originating on the bridge

 	sysPath := filepath.Join("/proc/sys/net/ipv6/conf/", config.BridgeName, "accept_ra")