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 From:  Michel Servaes <michel at mcmc dot be>
 To:  monowall <m0n0wall at lists dot m0n0 dot ch>
 Subject:  Re: [m0n0wall] VLANs not really working ? -solved! -not working anymore, after reboot !
 Date:  Tue, 15 Jul 2008 20:40:22 +0200
How should I make the MTU stick after a reboot of monowall ?
I installed b13 (which obviously rebooted), and my sites stopped working 
again, when trying to go via a VLAN.

I did an ifconfig, and saw that all my VLAN's are back at 1500, how do I 
make the MTU permanent ?
I guess that I have to modify the config.xml, and reload it - but a more 
cosmetic option might be handy :)

kind regards,

Chris Buechler wrote:
> On Sun, Jul 13, 2008 at 1:48 PM, Michel Servaes <michel at mcmc dot be> wrote:
>> I think I solved my issue here... since VLAN tagging is 4 bytes more than
>> normal Ethernet (I've been digging), I gathered that having a larger MTU at
>> VLAN level could have some troubles at the LAN being 1500.
>> So I lowered the MTU value of all my VLAN's to 1496, and kept LAN/WAN at
>> 1500 - and voila, my troubles went away !!  (didn't even have to reboot
>> anything - nor the monowall, nor my laptop, it just started working after :
>> ifconfig vlan0 mtu 1496
>> ifconfig vlan1 mtu 1496
>> ...
>> I can now access the internet without any troubles on each VLAN.
> That's what the new NIC should have resolved, it should allow the
> larger frames with the VLAN tagging.  Apparently it was an issue with
> your switch rather than your NIC. This is a suitable work around since
> it fixes PMTUD, so you should be fine running this way.
> -Chris
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