D'après la doc, ce n'est pas toujours le cas, mais ça pose très souvent des problèmes (recherche dans les archives d'une quelconque ML, et tu verras).
-m MSS Causes pppoe to clamp the TCP maximum segment size at the specified value. Because of PPPoE overhead, the maximum segment size for PPPoE is smaller than for normal Ethernet encapsulation. This could cause problems for machines on a LAN behind a gateway using PPPoE. If you have a LAN behind a gateway, and the gateway connects to the Internet using PPPoE, you are strongly recommended to use a -m 1412 option. This avoids having to set the MTU on all the hosts on the LAN.
[^] # Re: pilote STH
Posté par Jar Jar Binks . En réponse à la dépêche The Register: Mandrake 8.1 plus facile que WindowsXP. Évalué à 1.
-m MSS Causes pppoe to clamp the TCP maximum segment size at the specified value. Because of PPPoE overhead, the maximum segment size for PPPoE is smaller than for normal Ethernet encapsulation. This could cause problems for machines on a LAN behind a gateway using PPPoE. If you have a LAN behind a gateway, and the gateway connects to the Internet using PPPoE, you are strongly recommended to use a -m 1412 option. This avoids having to set the MTU on all the hosts on the LAN.