Re: NAT over vlan problem

On Wed, Aug 03, 2005 at 06:39:43PM -0400, Jamie ffolliott wrote:
> All vlan interfaces and eth0 have mtu set to 1480, to deal with
> oversize ethernet frames from 802.1q's extra 4byte header.

I believe this is the problem.

Try leaving the MTU at 1500 and using the e100 driver, not eepro100.

The e100 driver takes care of the oversized packet problem so no MTU
compensation is neccessary.

The fact that small packets come through properly also indicate that
the problem is MTU related, since the http packets will have the
maximum allowed size.

Admittedly, when adjusting the MTU down there should be no problem,
but unless you make the same adjustment on _all_ interfaces on that
layer 2 network I guess Linux will be unhappy when large packets
(over 1480 bytes, but under 1500 bytes which is the MTU at the
sender) arrive, just like when the driver/NIC do not handle this
properly for packets > 1500 bytes.


//Peter