[Guy Harris <guy@xxxxxxxxxxxx>]

Eloy Paris wrote:

> Dumb question: how does one know whether an Ethernet frame includes the
> FCS field?

In this case, i.e. Ethernet frames encapsulated within another protocol, 
one reads the protocol specification for the protocol that encapsulates 
Ethernet frames and checks whether it says that the protocol 
encapsulates Ethernet frames complete with FCS or Ethernet frames 
without the FCS.