Are PPPoE and PPPoA the same thing? (tricky question)

Discussion in 'Networking Issues' started by joseangel, Aug 9, 2005.

  1. joseangel

    joseangel Network Guru Member

    The answer does not come that easy, please, read on to know exactly what I am asking.

    I think know what PPPoA is. It just an ATM frame format that contains a simple plain PPP message (control or data messages does not matter).

    In fact, that simple encaposulation tranlates into a very simple scenario for PPPoA:

    DSL--------------DSL | STM-1-----------STM-1

    I also know a bit about PPPoE but I am not so sure. I think it is a negotiation protocol between WRT54G and ADSL2MUE that lets WRT54G find ADSL2MUE plus an encapsulation of PPP over ethernet.

    My guess is that it translates into a not so simple scenario:

    L2: PPP ------------------------------------------------------- PPP
    L2: Ethernet -------- Eth | ATM ------------------------------- ATM
    L1: Ethernet -------- Eth | DSL -------- DSL | STM-1 --------- STM-1
    WRT54G --------------- ADS2MUE ------------ DSLAM -------- Concentrator

    This PPPoE schematic is my best guess but , is it correct? I mean:

    PPPoE just specifies the encapsulation and negotiation between WRT54G and ADSL2MUE? If so, then ADSL2MUE translates from PPPoE into PPPoA, am I rigth? Also, if it is so, then any PPPoA connection (like the one with WAG54G) can be turned into PPPoE just by using a PPPoE/PPPoA converter like any Eth/ADSL modem would do.

    Could you please tell me what am I doing wrong with this line of thinking?

    Because if I am not wrong, a modem would need to implement PPPoE gateway, PPPoA client, translation betwen those two and RFC1483 modes to be a all-in-one modem. On the other hand, any router with an ethernet interface would only need to be able to become PPPoE client (only when needed) to be a perfect match for the perfect ADSL modem.

    Am I wrong? Please, tell me where I am wrong because I can feel I am wrong but I can not find out why (and that's getting me nuts). :cry: It cannot believe that a modem has to be far more complex than the router.
  2. joseangel

    joseangel Network Guru Member

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