[j-nsp] VLAN tagging on fxp?

[Kristian Larsson]

I'm in an environment where I need to tag the
traffic to a junipers out-of-band management port.
After configuring the port I ran into some problems.. 
ssh went just fine but when trying to upload/download
new firmware it just stopped. Debugging turned out that
subinterfaces to the fxp0 interface have a MTU of 1496.

Is it possible to change this?
mtu does not seem to be an option on the fxp interface!?
I tried setting it manually with ifconfig but to no avail

Juniper: feature request!?

//Kristian

    fxp0 {
        vlan-tagging;
        unit 10 {
            vlan-id 10;
            family inet {
                address xx.xx.xx.xx/24;
            }

 Logical interface fxp0.10 (Index 67) (SNMP ifIndex 25) 
    Flags: SNMP-Traps VLAN-Tag [ 0x8100.10 ]  Encapsulation: ENET2
    Bandwidth: 10mbps
    Input packets : 2295 
    Output packets: 2575
    Protocol inet, MTU: 1496