Merge pull request #897 from tomdee/fix-vxlan-mtu

backend/vxlan: Return correct MTU value
flannel-io · Dec 11, 2017 · 1cea4d1 · 1cea4d1
2 parents 7257bcc + f72fa98
commit 1cea4d1
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Showing 2 changed files with 5 additions and 6 deletions.
diff --git a/backend/vxlan/device.go b/backend/vxlan/device.go
@@ -144,10 +144,6 @@ func (dev *vxlanDevice) MACAddr() net.HardwareAddr {
 	return dev.link.HardwareAddr
 }
 
-func (dev *vxlanDevice) MTU() int {
-	return dev.link.MTU
-}
-
 type neighbor struct {
 	MAC net.HardwareAddr
 	IP  ip.IP4

diff --git a/backend/vxlan/vxlan_network.go b/backend/vxlan/vxlan_network.go
@@ -33,11 +33,14 @@ import (
 
 type network struct {
 	backend.SimpleNetwork
-	extIface  *backend.ExternalInterface
 	dev       *vxlanDevice
 	subnetMgr subnet.Manager
 }
 
+const (
+	encapOverhead = 50
+)
+
 func newNetwork(subnetMgr subnet.Manager, extIface *backend.ExternalInterface, dev *vxlanDevice, _ ip.IP4Net, lease *subnet.Lease) (*network, error) {
 	nw := &network{
 		SimpleNetwork: backend.SimpleNetwork{
@@ -77,7 +80,7 @@ func (nw *network) Run(ctx context.Context) {
 }
 
 func (nw *network) MTU() int {
-	return nw.dev.MTU()
+	return nw.ExtIface.Iface.MTU - encapOverhead
 }
 
 type vxlanLeaseAttrs struct {