How does one set interface mtu option of the DHCP server for jumbo frames?

zxvv

How do you set the interface-mtu option of dhcpd to 9000?

Here's what I've tried:

"Additional BOOTP/DHCP Options" has entries consisting of:

<option number="">  <type> <value></value></type></option>

The descriptions says "For a list of available options please visit this URL."
http://www.iana.org/assignments/bootp-dhcp-parameters/

The URL says option 26 is "Interface MTU", so I entered (screenshot below):

26        Unsigned 16-bit-interger      9000

And the resulting /var/dhcpd/etc/dhcpd.conf contains:

subnet 172.16.4.0 netmask 255.255.255.0 {
 ...
        option custom-lan-0 9000;
}

After saving the change and bouncing the dhcpd servers, dhcp clients still get configured for 1500 mtu.

I would have expected dhcpd.conf to have something like "option interface-mtu 9000;", so perhaps I'm not using the GUI correctly.

Does anyone have any ideas about how to configure MTU?

dhcpd-mtu.gif_thumb

zxvv

I have submited a pull request in hopes of resolving the capability to set MTU on dhcp pools.

https://github.com/pfsense/pfsense/pull/3222