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etherip and VLANs and MTUs (oh my?)


I'm curious if vlan(4)s over etherip(4) tunnels are supported. The vlan(4) man 
page does not mention that etherip(4) is a supported VLAN capable device. Of 
course the MTU seems to be adjustable which would make it possible to make it 4 
bytes larger for the VLAN tag in the Ethernet frame. Of some small consequence 
seems to be that you can't bridge dissimilar MTUs with bridge(4) but that 
shouldn't be of issue if your VLANs (with parent interfaces of etherip(4)s) are 
of the correct MTU, I'm assuming.

I did do some testing and it appeared that VLAN traffic was working and 
properly separated over an etherip interface, but the MTU considerations I 
don't know the answers to.

So my questions are:

 - Are tagged VLANs supported over an etherip(4) interface?
 - Do I need to increase the MTU of the etherip interface for the VLAN tag?
   - I suppose there is no practical consequence to doing this anyway because 
(if used as a trunk link) there wouldn't be any non-VLAN tagged traffic anyway 
to use the larger MTU.
 - Anything else I'm not considering by running VLANs over an etherip(4) 

- Jesse

Jesse Peterson <>

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