  <varlistentry>
  <term><emphasis remap='B'>mtu</emphasis></term>
  <listitem>
<para>
Set the MTU for the route(s) to the remote endpoint and/or subnets. This is sometimes
required when the overhead of the IPsec encapsulation would cause the packet the become
too big for a router on the path. Since IPsec cannot trust any unauthenticated ICMP
messages, PATH MTU discovery does not work. This can also be needed when using "6to4"
IPV6 deployments, which adds another header on the packet size.

Acceptable values are positive numbers. There is no default.
</para>
  </listitem>
  </varlistentry>

