Port Control Protocol (PCP) Proxy Function
RFC 7648

Document Type RFC - Proposed Standard (September 2015; No errata)
Last updated 2015-10-14
Replaces draft-bpw-pcp-proxy
Stream IETF
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Stream WG state Submitted to IESG for Publication
Document shepherd Dave Thaler
Shepherd write-up Show (last changed 2015-05-29)
IESG IESG state RFC 7648 (Proposed Standard)
Consensus Boilerplate Yes
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Responsible AD Brian Haberman
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IANA IANA review state IANA OK - No Actions Needed
IANA action state No IC
Internet Engineering Task Force (IETF)                      S. Perreault
Request for Comments: 7648                           Jive Communications
Category: Standards Track                                   M. Boucadair
ISSN: 2070-1721                                           France Telecom
                                                                R. Penno
                                                                 D. Wing
                                                                   Cisco
                                                             S. Cheshire
                                                                   Apple
                                                          September 2015

               Port Control Protocol (PCP) Proxy Function

Abstract

   This document specifies a new Port Control Protocol (PCP) functional
   element: the PCP proxy.  The PCP proxy relays PCP requests received
   from PCP clients to upstream PCP server(s).  A typical deployment
   usage of this function is to help establish successful PCP
   communications for PCP clients that cannot be configured with the
   address of a PCP server located more than one hop away.

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/rfc7648.

Perreault, et al.            Standards Track                    [Page 1]
RFC 7648                        PCP Proxy                 September 2015

Copyright Notice

   Copyright (c) 2015 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
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Use Case: The NAT Cascade . . . . . . . . . . . . . . . .   4
     1.2.  Use Case: The PCP Relay . . . . . . . . . . . . . . . . .   5
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Operation of the PCP Proxy  . . . . . . . . . . . . . . . . .   6
     3.1.  Optimized Hairpin Routing . . . . . . . . . . . . . . . .   8
     3.2.  Termination of Recursion  . . . . . . . . . . . . . . . .   9
     3.3.  Source Address for PCP Requests Sent Upstream . . . . . .  10
     3.4.  Unknown Opcodes and Options . . . . . . . . . . . . . . .  10
       3.4.1.  No NAT Is Co-located with the PCP Proxy . . . . . . .  10
       3.4.2.  PCP Proxy Co-located with a NAT Function  . . . . . .  10
     3.5.  Mapping Repair  . . . . . . . . . . . . . . . . . . . . .  11
     3.6.  Multiple PCP Servers  . . . . . . . . . . . . . . . . . .  11
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     5.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

Perreault, et al.            Standards Track                    [Page 2]
RFC 7648                        PCP Proxy                 September 2015

1.  Introduction

   This document defines a new Port Control Protocol (PCP) [RFC6887]
   functional element: the PCP proxy.  As shown in Figure 1, the
   PCP proxy is logically equivalent to a PCP client back-to-back with a
   PCP server.  The "glue" between the two is what is specified in this
   document.  Other than that "glue", the server and the client behave
   exactly like their regular counterparts.

   The PCP proxy is responsible for relaying PCP messages received from
   PCP clients to upstream PCP servers and vice versa.

   Whether or not the PCP proxy is co-located with a flow-aware function
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