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Versions: 00                                                            
INTERNET-DRAFT    "Network Working Group"                 G. Chanteau
                                                          Y. Codaccioni
                                                          V. Faineant
Document: draft-ietf-udlr-pppoe-00.txt                    France Telecom
Expires: April 2002                                       November 2001


                       Using PPPoE with LLTM Mechanism
                   <draft-ietf-udlr-pppoe-00.txt>


Status of this Memo

   This document is an Internet-Draft and is in full conformance
   with all provisions of Section 10 of RFC2026.


   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
        http://www.ietf.org/ietf/1id-abstracts.txt
   The list of Internet-Draft Shadow Directories can be accessed at
        http://www.ietf.org/shadow.html.


Abstract

   This memo describes the use and the configuration of the PPPoE over a
   UniDirectionnal Link such as satellite network. This document explains
   the advantages of the PPPoE and LLTM in such architecture.




Table of Contents

   Status of this Memo .............................................. 1
   Abstract ......................................................... 1
  1. Introduction ................................................... 2
  2. Network architecture ........................................... 2
 2.1 Equipments description ......................................... 3
 2.2 Connections description ........................................ 3
 2.3 Multicast....................................................... 3
  3. Advantages ..................................................... 4
   4. Evolutions .................................................... 5
 4.1 Multi-receiver connectivity .................................... 5
   5. References .................................................... 6
   6. Author's Addresses ............................................ 6
   7. Full copyright statement ...................................... 7












Chanteau & Codaccioni & Faineant                               [Page 1]


INTERNET-DRAFT          Using PPPoE with LLTM             November 2001




1. Introduction

   The initial idea was to create a real satellite local loop where a
   satellite broadband Internet access can replace a terrestrial one
   in areas that are non covered by terrestrial high speed Internet
   access such as ADSL. This architecture remains open and in order
   to provide the same type of services than in ADSL networks, an
   interconnection with a Broadband Access Server (BAS) is needed.
   This interconnection uses the PPPoE (PPP over Ethernet).

   This document explains the advantages of the PPPoE and LLTM [RFC 3077]
   in such a satellite Local Loop : compatibility with all IP world and
   performances equivalent to ADSL. It also shows the possible
   evolutions of this architecture.


2. Network architecture


                 Unidirectional Link
              -------------<-----------
              |                       |
              |                       |
              |                       |
              |                       |
              |                       |
             \|/                      .
              .                      /|\
              |                       |
          ---------               ---------         --------
 Ethernet | PPPoE/|  IP Networks  | LLTM  |  PPPoE  | BAS  |
   -------| LLTM  |-------->------|Server |---------|      |
          | Router|               |       |         |      |
      |   ---------               ---------         --------
      |  ____                                           |
      |--|PC|                                           |
      |  ----                                        --------
      |  ____  LAN                                   | ISP  |
      |--|PC|                                        --------
      |  ----


   Figure 1 : Connectivity to a BAS via PPPoE/LLTM

   In the Figure 1, the Connections without any arrow are
   bidirectionnal.















Chanteau & Codaccioni & Faineant                               [Page 2]


INTERNET-DRAFT          Using PPPoE with LLTM             November 2001


2.1. Equipments description

   Here are the description of the main equipments of this
   architecture :

   - the end user is a PC on a LAN.
   It integrates an Ethernet card.

   - the satellite terminal is a router with an LLTM client
   (implementing the RFC 3077).
   It integrates one satellite reception card, one Ethernet card
   and one bidirectional interface connected to the Internet.

   Firstly, it transports the traffic from the end users to
   the Internet via the return channel which can be either
   satellite or terrestrial.

   Secondly, it receives traffic from the DVB channel
   (previously coming from the Internet) via its DVB interface
   and deliver it to the end users.

   - the LLTM server (implementing the RFC 3077) is acting as
     an Ethernet bridge.

   This is the endpoint of the GRE tunnel where traffic is
   encapsulated and decapsulated. The LLTM server is
   directly connected to a BAS.


   - the BAS (Broadband Access Server) manages the PPPoE connection.
   The PPPoE can end into the BAS (open model) or continue and end into
   the RADIUS server of an ISP (closed model). The PPPoE authentication
   is done where the PPPoE tunnel ends.



2.2 Connections description (Unicast)


   Here are the different steps of a connection to Internet :

        - when an end user tries to go on the Internet, the satellite
        terminal implements the LLTM : it initiates first a GRE tunnel
        between its DVB interface and the LLTM server. Now a LAN has
        been emulated and all the Ethernet frames can be directed to
        the LLTM server and therefore to the BAS.















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INTERNET-DRAFT          Using PPPoE with LLTM             November 2001



        - the satellite terminal exchanges pieces of information with
        the BAS (initiation session) in order to initiate the PPPoE
        session.

        - In case of cloded model the BAS redirect the PPP connection
        to the right ISP through a L2TP tunnel.

        - the end user can connect to a distant server of the Internet.



2.3 Multicast


   It is important to notice that PPPoE supports only PPP connection for
   Unicast flows. The multicast is provided directly by the ASP using IP
   over LLTM. In this configuration, the ASP can offer n to m multicast
   services.
   There is also possibility to offer the Mbone connectity through the BAS
   without using PPPoE.


3. Advantages



   The Local Satellite Loop architecture offers the following advantages :


        - a return channel flexibility : the use of LLTM allows to
        define an access network wether with a satellite return channel
        or with a terrestrial return channel. Besides a standby
        terrestrial link can be used automatically in case of failure
        of the satellite return channel.


        - a multi-ISP configuration for the Internet access.

        - a difference is made between the ASP and the ISP

        - complementarity with the ADSL network :
                * performances : more than 128 kbps for the return channel
                and up to 40 Mbps for a gateway throughput
                * client segmentation : corporate or residential
                * interconnection with the terrestrial network
                * reduction of the access costs
                * re-use of the ADSL management system (accounting,
                billing, etc.)

        - interactif Multicast support (m to m)









Chanteau & Codaccioni & Faineant                               [Page 4]


INTERNET-DRAFT          Using PPPoE with LLTM             November 2001


4. Conclusion


The Local Satellite Loopb architecture has been already validated in laboratory.
A real experimentation will begin on the fourth quarter of 2001 with a few tens
of satellite terminals. Different evolutions are studied on multicast and security
aspects.


5. References

   [UDLR] E. Duros, W. Dabbous, H. Izumiyama, N. Fujii, Y. Zhang, "A
   Link-Layer Tunneling Mechanism for Unidirectional Links", RFC 3077,
   March 2001

   [PPPoE] L. Mamakos, K. Lidl, J. Evarts, D. Carrel, D. Simone, R.
   Wheeler, "A Method for Transmitting PPP Over Ethernet (PPPoE)",
   RFC 2516, February 1999

   [GRE] D. Farinacci, T. Li, S. Hanks, D. Meyer, P. Traina, "Generic
   Routing Encapsulation (GRE)", RFC 2784, March 2000



6. Author's Addresses

   Gilles Chanteau
   France Telecom R&D
   38/40 rue du G‰n‰ral Leclerc
   92131 Issy-Les-Moulineaux Cedex
   France
   Phone: (+33) 1 45 29 58 67
   EMail : gilles.chanteau@rd.francetelecom.com


   Yann Codaccioni
   France Telecom R&D
   38/40 rue du G‰n‰ral Leclerc
   92131 Issy-Les-Moulineaux Cedex
   France
   Phone: (+33) 1 45 29 64 67
   EMail : yann.codaccioni@rd.francetelecom.com

   Virginie Fain‰ant
   France Telecom R&D
   38/40 rue du G‰n‰ral Leclerc
   92131 Issy-Les-Moulineaux Cedex
   France
   Phone: (+33) 1 45 29
   EMail : virginie.faineant@rd.francetelecom.com












Chanteau & Codaccioni & Faineant                               [Page 5]

INTERNET-DRAFT          Using PPPoE with LLTM             November 2001


7. Full copyright statement

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist its implementation may be prepared, copied, published and
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   included on all such copies and derivative works.

   However, this document itself may not be modified in any way, such as
   by removing the copyright notice or references to the Internet
   Society or other Internet organizations, except as needed for the
   purpose of developing Internet standards in which case the procedures
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   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
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