Modular Layer 2 (ml2) configuration options
- The Modular Layer 2 (ml2) plug-in has two components,
- network types and mechanisms, that can be configured
- separately. Such configuration options are described in the
- subsections.
+ The Modular Layer 2 (ml2) plug-in has two components:
+ network types and mechanisms. You can configure these
+ components separately. This section describes these
+ configuration options.
+
+ MTU bug with VXLAN tunnelling
+ Due to a bug in Linux Bridge software maximum
+ transmission unit (MTU) handling, using VXLAN tunnels does
+ not work by default.
+
+
+ A simple workaround is to increase the MTU value
+ of the physical interface and physical switch
+ fabric by at least 50 bytes. For example, increase
+ the MTU value to 1550. This value enables an
+ automatic 50-byte MTU difference between the
+ physical interface (1500) and the VXLAN interface
+ (automatically 1500-50 = 1450). An MTU value of
+ 1450 causes issues when virtual machine taps are
+ configured at an MTU value of 1500.
+
+
+ Another workaround is to decrease the virtual
+ ethernet devices' MTU. Set the
+ option to
+ 1450 in the neutron.conf
+ file, and set all guest virtual machines' MTU to
+ the same value by using a DHCP option. For
+ information about how to use this option, see
+ Configure OVS plug-in.
+
+
+ Modular Layer 2 (ml2) Flat Type configuration