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



  • 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?



  • 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


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