vlan0 on em0 has mtu 1496

[Brooks Davis]

On Thu, Apr 17, 2003 at 08:34:47PM -0400, Mike Tancsa wrote:
> At 05:19 PM 17/04/2003 -0700, Brooks Davis wrote:
> >On Thu, Apr 17, 2003 at 08:13:55PM -0400, David Gilbert wrote:
> >> Why does a vlan created against em0 have a mtu of 1496.
> >
> >Because the vlan header takes up 4 bytes.  With em(4) devices it looks
> >like fixing that should be a simple matter of raising the real
> >interface's MTU to 1504.
> 
> Why the difference in behavior vs how the fxp driver works with respect to 
> vlans ?

I don't know.  In current both have the VLAN_MTU capability set, but I
don't seem to be getting consistant results from 4.x systems.

-- Brooks

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