MAPOS/PPP Tunneling mode
RFC 3186

Document Type RFC - Informational (December 2001; No errata)
Was draft-shimizu-ppp-mapos (individual)
Last updated 2013-03-02
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Network Working Group                                         S. Shimizu
Request for Comments: 3186                                     T. Kawano
Category: Informational                                      K. Murakami
                                            NTT Network Innovation Labs.
                                                                E. Beier
                                                              DeTeSystem
                                                           December 2001

                        MAPOS/PPP Tunneling mode

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2001).  All Rights Reserved.

IESG Note

   This memo documents a way of tunneling PPP over Sonet over MAPOS
   networks.  This document is NOT the product of an IETF working group
   nor is it a standards track document.  It has not necessarily
   benefited from the widespread and in depth community review that
   standards track documents receive.

Abstract

   This document specifies tunneling configuration over MAPOS (Multiple
   Access Protocol over SONET/SDH) networks.  Using this mode, a MAPOS
   network can provide transparent point-to-point link for PPP over
   SONET/SDH (Packet over SONET/SDH, POS) without any additional
   overhead.

1. Introduction

   MAPOS [1][2] frame is designed to be similar to PPP over SONET/SDH
   (Packet over SONET/SDH, POS)[3][4] frame (Figure 1).

Shimizu, et al.              Informational                      [Page 1]
RFC 3186                MAPOS/PPP Tunneling mode           December 2001

      a) MAPOS frame header (version 1)
         +-----------+-----------+-----------+-----------+
         | Address   | Control   | Protocol              |
         |  8 bits   | fixed,0x03| 16 bits               |
         +-----------+-----------+-----------+-----------+

      b) MAPOS frame header (MAPOS 16)
         +-----------+-----------+-----------+-----------+
         | Address               | Protocol              |
         |   16bits              | 16 bits               |
         +-----------+-----------+-----------+-----------+

      c) PPP frame header
         +-----------+-----------+-----------+-----------+
         | Address   | Control   | Protocol              |
         | fixed,0xFF| fixed,0x03| 16 bits               |
         +-----------+-----------+-----------+-----------+

      Figure 1. Header similarity of MAPOS frame and POS frame

   This means that a MAPOS network can easily carry POS frames with no
   additional header overhead by rewriting only 1 or 2 octets.  PPP
   tunneling configuration over MAPOS networks (MAPOS/PPP tunneling
   mode) provides for efficient L2 multiplexing by which users can share
   the cost of high speed long-haul links.

   This document specifies MAPOS/PPP tunneling mode.  In this mode, a
   MAPOS network provides a point-to-point link for those who intend to
   connect POS equipment.  Such link is established within a MAPOS
   switch, or between a pair of MAPOS switches that converts between POS
   header and MAPOS header for each L2 frame.

   Chapter 2 describes the specification in two parts.  First part is
   user network interface (UNI) specification and the second part is
   operation, administration, management and provisioning (OAM&P)
   description.  Other issues such as congestion avoidance, end-to-end
   fairness control are out of scope of this document.

   Implementation issues are discussed in Chapter 3.  Security
   considerations are noted in Chapter 4.

Shimizu, et al.              Informational                      [Page 2]
RFC 3186                MAPOS/PPP Tunneling mode           December 2001

2. MAPOS/PPP tunneling mode

2.1 Overview

   MAPOS/PPP tunneling mode is based on header rewriting.  Figure 2.
   shows an example of MAPOS/PPP tunneling mode.  The MAPOS network uses
   MAPOS 16 [2] in this example.  Consider a tunneling path between
   customer premise equipment (CPE) A and CPE B which are industry
   standard POS equipment.  The ingress/egress MAPOS switches A/B
   assigns unique MAPOS addresses (0x0203 and 0x0403) to the CPEs.
   These MAPOS addresses are used in the MAPOS network, for frame
   forwarding between CPE A and CPE B.  NSP [5] will not be running
   between the CPEs and the switches in this case.

   MAPOS switch A rewrites the first 2 octets of every frame from CPE A,
   which are fixed as 0xFF and 0x03, to the MAPOS address of its peer,
   which is 0x0403.  Frames are forwarded by the MAPOS network and
   arrives at the egress MAPOS switch B which rewrites the first 2
   octets to their original values.  If MAPOS v1 [1] is used in the
   MAPOS network, only the first octet is rewritten.

    +-----+ POS/0x0203 +--------+                  +--------+
    |CPE A|<---------->|MAPOS   |     MAPOS        |MAPOS   |<---
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