Port Control Protocol (PCP)
RFC 6887

Internet Engineering Task Force (IETF)                      D. Wing, Ed.
Request for Comments: 6887                                         Cisco
Category: Standards Track                                    S. Cheshire
ISSN: 2070-1721                                                    Apple
                                                            M. Boucadair
                                                          France Telecom
                                                                R. Penno
                                                                   Cisco
                                                              P. Selkirk
                                                                     ISC
                                                              April 2013

                      Port Control Protocol (PCP)

Abstract

   The Port Control Protocol allows an IPv6 or IPv4 host to control how
   incoming IPv6 or IPv4 packets are translated and forwarded by a
   Network Address Translator (NAT) or simple firewall, and also allows
   a host to optimize its outgoing NAT keepalive messages.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6887.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

Wing, et al.                 Standards Track                    [Page 1]
RFC 6887               Port Control Protocol (PCP)            April 2013

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Deployment Scenarios . . . . . . . . . . . . . . . . . . .  5
     2.2.  Supported Protocols  . . . . . . . . . . . . . . . . . . .  5
     2.3.  Single-Homed Customer Premises Network . . . . . . . . . .  5
   3.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   4.  Relationship between PCP Server and Its PCP-Controlled
       Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   5.  Note on Fixed-Size Addresses . . . . . . . . . . . . . . . . . 10
   6.  Protocol Design Note . . . . . . . . . . . . . . . . . . . . . 11
   7.  Common Request and Response Header Format  . . . . . . . . . . 13
     7.1.  Request Header . . . . . . . . . . . . . . . . . . . . . . 14
     7.2.  Response Header  . . . . . . . . . . . . . . . . . . . . . 15
     7.3.  Options  . . . . . . . . . . . . . . . . . . . . . . . . . 16
     7.4.  Result Codes . . . . . . . . . . . . . . . . . . . . . . . 19
   8.  General PCP Operation  . . . . . . . . . . . . . . . . . . . . 20
     8.1.  General PCP Client: Generating a Request . . . . . . . . . 21
       8.1.1.  PCP Client Retransmission  . . . . . . . . . . . . . . 22
     8.2.  General PCP Server: Processing a Request . . . . . . . . . 24
     8.3.  General PCP Client: Processing a Response  . . . . . . . . 25
     8.4.  Multi-Interface Issues . . . . . . . . . . . . . . . . . . 27
     8.5.  Epoch  . . . . . . . . . . . . . . . . . . . . . . . . . . 27
   9.  Version Negotiation  . . . . . . . . . . . . . . . . . . . . . 29
   10. Introduction to MAP and PEER Opcodes . . . . . . . . . . . . . 30
     10.1. For Operating a Server . . . . . . . . . . . . . . . . . . 33
     10.2. For Operating a Symmetric Client/Server  . . . . . . . . . 35
     10.3. For Reducing NAT or Firewall Keepalive Messages  . . . . . 37
     10.4. For Restoring Lost Implicit TCP Dynamic Mapping State  . . 38
   11. MAP Opcode . . . . . . . . . . . . . . . . . . . . . . . . . . 39
     11.1. MAP Operation Packet Formats . . . . . . . . . . . . . . . 40
     11.2. Generating a MAP Request . . . . . . . . . . . . . . . . . 43
       11.2.1. Renewing a Mapping . . . . . . . . . . . . . . . . . . 44