RFC 1619 (rfc1619) - Page 1 of 4

PPP over SONET/SDH

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Network Working Group                                         W. Simpson
Request for Comments: 1619                                    Daydreamer
Category: Standards Track                                       May 1994


                           PPP over SONET/SDH



Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.



Abstract

   The Point-to-Point Protocol (PPP) [1] provides a standard method for
   transporting multi-protocol datagrams over point-to-point links.
   This document describes the use of PPP over Synchronous Optical
   Network (SONET) and Synchronous Digital Heirarchy (SDH) circuits.

   This document is the product of the Point-to-Point Protocol Working
   Group of the Internet Engineering Task Force (IETF).  Comments should
   be submitted to the  mailing list.



Applicability

   This specification is intended for those implementations which desire
   to use the PPP encapsulation over high speed private point-to-point
   links, such as intra-campus single-mode fiber which may already be
   installed and unused.  Because the PPP encapsulation has relatively
   low overhead, it is anticipated that significantly higher throughput
   can be attained compared to other SONET/SDH payload mappings, at a
   significantly lower cost for line termination equipment.










Simpson                                                         [Page i]
RFC 1619                   PPP over SONET/SDH                   May 1994


                           Table of Contents


     1.     Introduction ..........................................    1

     2.     Physical Layer Requirements ...........................    1

     3.     Framing ...............................................    2

     4.     Configuration Details .................................    3

     SECURITY CONSIDERATIONS ......................................    3

     REFERENCES ...................................................    3

     ACKNOWLEDGEMENTS .............................................    3

     CHAIR'S ADDRESS ..............................................    4

     AUTHOR'S ADDRESS .............................................    4






























Simpson                                                        [Page ii]
RFC 1619                   PPP over SONET/SDH                   May 1994


1.  Introduction

   PPP was designed as a standard method of communicating over point-
   to-point links.  Initial deployment has been over short local lines,
   leased lines, and plain-old-telephone-service (POTS) using modems.
   As new packet services and higher speed lines are introduced, PPP is
   easily deployed in these environments as well.

   This specification is primarily concerned with the use of the PPP
   encapsulation over SONET/SDH links.  Since SONET/SDH is by definition
   a point-to-point circuit, PPP is well suited to use over these links.

   The Synchronous Optical Network (SONET) [3] is an octet-synchronous
   multiplex scheme that defines a family of standard rates and formats.
   Despite the name, it is not limited to optical links.  Electrical
   specifications have been defined for single-mode fiber, multi-mode
   fiber, and CATV 75 ohm coaxial cable.  The transmission rates are
   integral multiples of 51.840 Mbps, which may be used to carry T3/E3
   bit-synchronous signals.  The allowed multiples are currently
   specified as

           STS-1    51.840         STS-18    933.120
           STS-3   155.520         STS-24  1,244.160
           STS-9   466.560         STS-36  1,866.240
           STS-12  622.080         STS-48  2,488.320


   The CCITT Synchronous Digital Heirarchy (SDH) defines a subset of
   SONET transmission rates beginning at 155.520 Mbps [5].

           SONET           SDH equivalent
           STS-3c          STM-1
           STS-12c         STM-4
           STS-48c         STM-16




2.  Physical Layer Requirements

   PPP treats SONET/SDH transport as octet oriented synchronous links.
   SONET/SDH links are full-duplex by definition.

   Interface Format

      PPP presents an octet interface to the physical layer.  There is
      no provision for sub-octets to be supplied or accepted.




Simpson
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