diff --git a/doc/source/admin/config-mtu.rst b/doc/source/admin/config-mtu.rst
index 73955d56389..4207809e46d 100644
--- a/doc/source/admin/config-mtu.rst
+++ b/doc/source/admin/config-mtu.rst
@@ -129,3 +129,12 @@ while the L3 agent provides an appropriate MTU value to instances using
 IPv6. IPv6 uses RA via the L3 agent because the DHCP agent only supports
 IPv4. Instances using IPv4 and IPv6 should obtain the same MTU value
 regardless of method.
+
+Networks with enabled vlan transparency
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In case of networks with enabled vlan transparency, if additional vlan tag is
+configured inside guest VM, MTU has to be lowered by 4 bytes to make space for
+additional vlan tag in the packet's header.
+For example, if network's MTU is set to ``1500``, value configured for the
+interfaces in the guest vm should be manually set to ``1496`` or less bytes.