They do, is the xl* driver.
After wrestling with this problem for months I have switched to pfsense. 
Communication between vlans works now.
Regards,
eric.


JR wrote:
> On Wed, May 7, 2008 at 8:31 PM,  <eric dot lopez at ues dot edu dot sv> wrote:
>   
>> We have monowall installed with four interfaces one of them is the WAN interface
>>  the other three manage 14 different tagged vlans. Users (about 300) browse the
>>  web without a problem. connectivity between vlans works at a basic level
>>  meaning that pinging any host works well but moving files between vlans is
>>  impossible. I have tested in many different ways, and proved that moving an 8
>>  bytes empty text file works flawlessly but anything bigger gets the network
>>  hang. However I can move the same big file outside monowall into another public
>>  IP without a problem.
>>  This is not a rules problem, the logs do not show anything being blocked.
>>     
>
> What kind of NIC's are you using/do they support VLAN tagging on m0n0wall?
> http://m0n0.ch/wall/hardware.php
>
> JR
>
>