Update vxlan.rst Added section about MTU sizes and examples.
Project: http://git-wip-us.apache.org/repos/asf/cloudstack-docs/repo Commit: http://git-wip-us.apache.org/repos/asf/cloudstack-docs/commit/cbd7a136 Tree: http://git-wip-us.apache.org/repos/asf/cloudstack-docs/tree/cbd7a136 Diff: http://git-wip-us.apache.org/repos/asf/cloudstack-docs/diff/cbd7a136 Branch: refs/heads/master Commit: cbd7a13622780142127f06bf2f0d2888afea3c68 Parents: be0f4dd Author: andrijapanic <andrijapa...@users.noreply.github.com> Authored: Wed Nov 26 13:10:32 2014 +0100 Committer: andrijapanic <andrijapa...@users.noreply.github.com> Committed: Wed Nov 26 13:10:32 2014 +0100 ---------------------------------------------------------------------- rtd/source/networking/vxlan.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/cloudstack-docs/blob/cbd7a136/rtd/source/networking/vxlan.rst ---------------------------------------------------------------------- diff --git a/rtd/source/networking/vxlan.rst b/rtd/source/networking/vxlan.rst index d3b54a8..85da616 100644 --- a/rtd/source/networking/vxlan.rst +++ b/rtd/source/networking/vxlan.rst @@ -73,6 +73,16 @@ To check the capability of your system, execute the following commands. # If it's not, your iproute2 utility doesn't support VXLAN. +Important note on MTU size +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +When new vxlan interfaces are created, kernel will obtain current MTU size of the physical interface (ethX or the bridge) +and then create vxlan interface/bridge that are exactly 50 bytes smaller than the MTU on physical interface/bridge. +This means that in order to support default MTU size of 1500 bytes inside VM, your vxlan interface/bridge must also +have MTU of 1500 bytes, meaning that your physical interface/bridge must have MTU of at least 1550 bytes. +In order to configure "jumbo frames" you can i.e. make physical interface/bridge with 9000 bytes MTU, then all the vxlan +interfaces will be created with MTU of 8950 bytes, and then MTU size inside VM can be set to 8950 bytes. + Advanced: Build kernel and iproute2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
