> Bill Cunningham wrote > If datagram and packet is the same, then what are frames? > TCP is carried by PPP frames. I'm not sure about APEX (rfc 3340) This is not new, is it what we are referring to? +---+--------------+----------------------+ ! # ! Layer name ! PDU ! +---+--------------+----------------------+ ! 7 ! Application ! Messages ! ! 6 ! Presentation ! Messages ! ! 5 ! Session ! Messages ! ! 4 ! Transport ! Segments ! ! 3 ! Network ! Packets or datagrams ! ! 2 ! Data Link ! Frames ! ! 1 ! Physical ! Bits ! +---+--------------+----------------------+ Michel.