Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Circuit Emulation over Packet (CEP)
RFC 4842

Network Working Group                                           A. Malis
Request for Comments: 4842                        Verizon Communications
Category: Standards Track                                        P. Pate
                                                       Overture Networks
                                                           R. Cohen, Ed.
                                                       Resolute Networks
                                                                D. Zelig
                                                       Corrigent Systems
                                                              April 2007

 Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH)
                  Circuit Emulation over Packet (CEP)

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.

Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   This document provides encapsulation formats and semantics for
   emulating Synchronous Optical Network/Synchronous Digital Hierarchy
   (SONET/SDH) circuits and services over MPLS.

Malis, et al.               Standards Track                     [Page 1]
RFC 4842              SONET/SDH Circuit Emulation             April 2007

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Requirements Notation  . . . . . . . . . . . . . . . . . . . .  4
   4.  Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   5.  CEP Encapsulation Format . . . . . . . . . . . . . . . . . . .  5
     5.1.  SONET/SDH Fragment . . . . . . . . . . . . . . . . . . . .  6
     5.2.  CEP Header . . . . . . . . . . . . . . . . . . . . . . . .  7
     5.3.  RTP Header . . . . . . . . . . . . . . . . . . . . . . . .  9
     5.4.  PSN Encapsulation  . . . . . . . . . . . . . . . . . . . . 11
   6.  CEP Operation  . . . . . . . . . . . . . . . . . . . . . . . . 11
     6.1.  CEP Packetizer and De-Packetizer . . . . . . . . . . . . . 11
     6.2.  Packet Synchronization . . . . . . . . . . . . . . . . . . 12
       6.2.1.  Acquisition of Packet Synchronization  . . . . . . . . 13
       6.2.2.  Loss of Packet Synchronization . . . . . . . . . . . . 13
   7.  SONET/SDH Maintenance Signals  . . . . . . . . . . . . . . . . 13
     7.1.  SONET/SDH to PSN . . . . . . . . . . . . . . . . . . . . . 13
       7.1.1.  CEP-AIS: AIS-P/V Indication  . . . . . . . . . . . . . 13
       7.1.2.  Unequipped Indication  . . . . . . . . . . . . . . . . 14
       7.1.3.  CEP-RDI: Remote Defect Indication  . . . . . . . . . . 15
     7.2.  PSN to SONET/SDH . . . . . . . . . . . . . . . . . . . . . 15
       7.2.1.  CEP-AIS: AIS-P/V Indication  . . . . . . . . . . . . . 15
       7.2.2.  Unequipped Indication  . . . . . . . . . . . . . . . . 16
   8.  SONET/SDH Transport Timing . . . . . . . . . . . . . . . . . . 16
   9.  SONET/SDH Pointer Management . . . . . . . . . . . . . . . . . 17
     9.1.  Explicit Pointer Adjustment Relay (EPAR) . . . . . . . . . 17
     9.2.  Adaptive Pointer Management (APM)  . . . . . . . . . . . . 19
   10. CEP Performance Monitors . . . . . . . . . . . . . . . . . . . 19
     10.1. Near-End Performance Monitors  . . . . . . . . . . . . . . 19
     10.2. Far-End Performance Monitors . . . . . . . . . . . . . . . 20
   11. Payload Compression Options  . . . . . . . . . . . . . . . . . 20
     11.1. Dynamic Bandwidth Allocation . . . . . . . . . . . . . . . 21
     11.2. Service-Specific Payload Formats . . . . . . . . . . . . . 21
       11.2.1. Fractional STS-1 (VC-3) Encapsulation  . . . . . . . . 21
         11.2.1.1.  Fractional STS-1 CEP Header . . . . . . . . . . . 23
         11.2.1.2.  B3 Compensation . . . . . . . . . . . . . . . . . 24
         11.2.1.3.  Actual Payload Size . . . . . . . . . . . . . . . 24
       11.2.2. Asynchronous T3/E3 STS-1 (VC-3) Encapsulation  . . . . 25
         11.2.2.1.  T3 Payload Compression  . . . . . . . . . . . . . 25
         11.2.2.2.  E3 Payload Compression  . . . . . . . . . . . . . 26
       11.2.3. Fractional VC-4 Encapsulation  . . . . . . . . . . . . 26
         11.2.3.1.  Fractional VC-4 Mapping . . . . . . . . . . . . . 27
         11.2.3.2.  Fractional VC-4 CEP Header  . . . . . . . . . . . 28
         11.2.3.3.  B3 Compensation . . . . . . . . . . . . . . . . . 29
         11.2.3.4.  Actual Payload Sizes  . . . . . . . . . . . . . . 30
   12. Signaling of CEP Pseudowires . . . . . . . . . . . . . . . . . 30