Mateusz Poliwczak
Mateusz Poliwczak
> Eg, if the admin configures 3000 but the interface MTU is only 2000, then we should lower the values to 1992 right? I believe that this is already done,...
> and then during LCP make that bigger based on the configured mru/mtu and detected values? Yeah, but LCP seems to be handled by the `pppd`, not by the `pppoe`...
So... (i think) that maybe only changing (removing) this: https://github.com/ppp-project/ppp/blob/13291f4c08ebe23afc5427c0e66f8ebb56305fbe/pppd/plugins/pppoe/plugin.c#L456-L459 would solve the issue?
Tested the above patch https://github.com/ppp-project/ppp/pull/573#issuecomment-3474034514 And it also seems to work: ```bash [mateusz@arch ~ ]$ ping -M do -s 1512 X.X.X.X%pppoe-wan PING X.X.X.X (83.1.5.152) 1512(1540) bytes of data. 1520 bytes...
@jkroonza updated the PR
That commit seems to be pre-rfc4638, so i guess the behavior back then was right, the commit basically allowed `MRU < 1492`.
> I wonder if there's some implementation that count on MRU < 1492 I doubt, but even if there are such, then this is still is configurable.
Aren't we already supporting rfc 4638, but up to 1500 mru? This only removes that restriction and allows >1500 mru.
If RFC 4638 does not happen in the discovery, then we still limit the MRU to 1492, see: https://github.com/ppp-project/ppp/blob/1affa97637a405b1557b3e7f1c23239bfe65889d/pppd/plugins/pppoe/discovery.c#L722-L728
See fd1dcdf758418f040da3ed801ab001b5e46854e7