diff --git a/doc/config-reference/networking/section_networking-plugins-ml2.xml b/doc/config-reference/networking/section_networking-plugins-ml2.xml index cb02cf32d9..f71cb6e1c4 100644 --- a/doc/config-reference/networking/section_networking-plugins-ml2.xml +++ b/doc/config-reference/networking/section_networking-plugins-ml2.xml @@ -8,10 +8,41 @@ xmlns:ns3="http://www.w3.org/1998/Math/MathML" xmlns:ns="http://docbook.org/ns/docbook" version="5.0"> 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