RG          LAC          UP(LNS)    AAA      CP(LNS)
     |    PPPoE   |              |        |          |
     |  Discovery |              |        |          |
    1|<---------->|              |        |          |
     |            |              |        |          |
     |  PPP LCP   |              |        |          |
    2|<---------->|                       |          |
     |            |          AAA          |          |
     |PPP PAP/CHAP|        Req/Rep        |          |
    3|<---------->|<--------------------->|          |
     |            |                                  |
     |            | L2TP Tunnel  |     L2TP Tunnel   |
     |            | Negotiation  |     Negotiation   |
     |            |   SCCRQ/     |       SCCRQ/      |
     |            |   SCCRP/     |       SCCRP/      |
     |            |   SCCCN      |       SCCCN       |
     |           4|<------------>|<------via Si----->|
     |            |              |                   |
     |            | L2TP Session |     L2TP Session  |
     |            | Negotiation  |     Negotiation   |
     |            |    ICRQ/     |        ICRQ/      |
     |            |    ICRP/     |        ICRP/      |
     |            |    ICCN      |        ICCN       |
     |           5|<------------>|<------via Si----->|
     |            |              |                   |
     |            |              | Create Subscriber |
     |            |              | Session Request   |
     |            |             6|<-----via Ci-------|
     |            |              | Create Subscriber |
     |            |              | Session Response  |
     |            |             7|------via Ci------>|
     |                                               |
     |          PAP/CHAP (Triggered by LNS)          |
    8|<--------------------------------------------->|
     |                                               |
     |            |              |        |    AAA   |
     |            |              |        |  Req/Rep |
     |            |              |       9|<-------->|
     |            |              |        |          |
     |                                               |
     |                   PPP IP6CP                   |
   10|<--------------------------------------------->|
     |                                               |
     |            |              | Update Subscriber |
     |            |              | Session Request   |
     |            |            11|<-----via Ci-------|
     |            |              | Update Subscriber |
     |            |              | Session Response  |
     |            |            12|------via Ci------>|
     |                           |                   |
     |       ND Negotiation      |   ND Negotiation  |
   13|<------------------------->|<-----via Si------>|
     |                           |                   |
     |            |              | Update Subscriber |
     |            |              | Session Request   |
     |            |            14|<-----via Ci-------|
     |            |              | Update Subscriber |
     |            |              | Session Response  |
     |            |            15|------via Ci------>|
     |            |              |                   |