> Hi, Hi Daniel,
> On Wed, Aug 23, 2023 at 04:58:40PM +0200, Marek Küthe wrote: > > PPPoE adds 8 bytes of overhead so that an MTU of 1432 can be used. I > > also have to do this at home with my DSL line for example. > > The MTU should be set on each side (on both peers) for this to work. > > Oh, I just realized I used the 1432 MTU in my earlier reply based on > Marek's math but since Luiz's underlay network is IPv6 this is not actually > correct. MTU=1440 is only correct on top of IPv4, for IPv6 the "optimal" > MTU is 1420 so with PPPoE involved that's MTU=1412. > > 1500 Ethernet payload > -40 IPv6 header > -8 UDP header > -32 Wg header > -8 PPPoE > =================== > 1412 wg tunnel MTU In my case, the PPPoE interface got MTU=1480. They might be stacking something else on top of it or PPPoE might have optional fields. I read somewhere that PPPoE might use either 8 or 20 bytes, but I'm not an expert on PPPoE. If I don't control both sides, I would use 1400 by default. > --Daniel
