Some providers (like init7.ch which already uses the Swisscom XGS-PON) do encapsulate their PPPoE traffic into a VLAN Tag (802.1Q or Q-Tagged). The reason for this is, that in the majority of the cases the provider is using a layer 2 network (last mile) of another provider, which uses VLAN tagging to differentiate the traffic to different service providers.
The configuration of the FortiGate is not too complicated in those cases. It is even possible to make the whole configuration directly off the WebGUI.
«FortiGate PPPoE inside a VLAN» weiterlesen