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Versions: (draft-bpw-softwire-upnp-pcp-interworking) 00 01 02 draft-ietf-pcp-upnp-igd-interworking

Network Working Group                                       M. Boucadair
Internet-Draft                                            France Telecom
Intended status: Standards Track                                R. Penno
Expires: June 26, 2011                                  Juniper Networks
                                                                 D. Wing
                                                                   Cisco
                                                               F. Dupont
                                                                     ISC
                                                       December 23, 2010


   Universal Plug and Play (UPnP) Internet Gateway Device (IGD)-Port
              Control Protocol (PCP) Interworking Function
                 draft-bpw-pcp-upnp-igd-interworking-01

Abstract

   This document specifies the behavior of the UPnP IGD (Internet
   Gateway Device)/PCP Interworking Function.  An UPnP IGD-PCP
   Interworking Function (IGD-PCP IWF) is required to be embedded in CP
   routers to allow for transparent NAT control in environments where
   UPnP is used in the LAN side and PCP in the external side of the CP
   router.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 26, 2011.

Copyright Notice



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   Copyright (c) 2010 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 . . . . . . . . . . . . . . . . . . . . . . . . .  4

   2.  Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . .  4

   3.  Architecture Model . . . . . . . . . . . . . . . . . . . . . .  5

   4.  UPnP IGD-PCP Interworking Function: Overview . . . . . . . . .  7
     4.1.  UPnP IGD-PCP: Variables  . . . . . . . . . . . . . . . . .  7
     4.2.  IGD-PCP: Methods . . . . . . . . . . . . . . . . . . . . .  9
     4.3.  UPnP IGD-PCP: Errors . . . . . . . . . . . . . . . . . . . 12

   5.  Specification of the IGD-PCP Interworking Function . . . . . . 13
     5.1.  PCP Server Discovery . . . . . . . . . . . . . . . . . . . 13
     5.2.  Control of the Firewall  . . . . . . . . . . . . . . . . . 13
     5.3.  NAT Control in LAN Side  . . . . . . . . . . . . . . . . . 14
     5.4.  Port Mapping Tables  . . . . . . . . . . . . . . . . . . . 14
     5.5.  Interworking Function Without NAT in the CP Router . . . . 14
     5.6.  NAT Embedded in the CP Router  . . . . . . . . . . . . . . 14
     5.7.  Creating a Mapping . . . . . . . . . . . . . . . . . . . . 15
       5.7.1.  AddAnyPortMapping()  . . . . . . . . . . . . . . . . . 15
       5.7.2.  AddPortMapping() . . . . . . . . . . . . . . . . . . . 16
     5.8.  Listing One or a Set of Mappings . . . . . . . . . . . . . 21
     5.9.  Delete One or a Set of Mappings: DeletePortMapping()
           or DeletePortMappingRange()  . . . . . . . . . . . . . . . 21
     5.10. Mapping Synchronisation  . . . . . . . . . . . . . . . . . 22

   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 22

   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 23

   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 23




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   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 23
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 23

   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24














































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1.  Introduction

   PCP [I-D.ietf-pcp-base] discusses the implementation of NAT control
   features that rely upon Carrier Grade NAT devices such as DS-Lite
   AFTR [I-D.ietf-softwire-dual-stack-lite] or NAT64
   [I-D.ietf-behave-v6v4-xlate-stateful].  Nevertheless, in environments
   where UPnP is used in the local network, an interworking function
   between UPnP IGD and PCP is required to be embedded in the CP router
   (an example is illustrated in Figure 1).

   Two configurations are considered:

   o  No NAT function is embedded in the CP router.  This is required
      for instance in DS-Lite or NAT64 deployments;

   o  The CP router embeds a NAT function.

                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                  PCP Server
        |                      |                           |
        | (1) AddPortMapping   |                           |
        |--------------------->|                           |
        |                      |   (2) PCP PINxy Request   |
        |                      |-------------------------->|
        |                      |                           |

                          Figure 1: Flow Example

   The UPnP IGD-PCP Interworking Function (IGD-PCP IWF) maintains a
   local mapping table which stores all active mappings instructed by
   internal UPnP Control Points.  This design choice restricts the
   amount of PCP messages to be exchanged with the PCP Server.

   Triggers for deactivating the UPnP IGD-PCP Interworking Function from
   the CP router and relying on a PCP-only mode are out of scope of this
   document.

   In the remaining, PINxy refers to one of the PIN44, PIN46, PING64 and
   PIN66 PCP OpCodes defined in [I-D.ietf-pcp-base].


2.  Acronyms

   This document make use of the following abbreviations:






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                   CP router Customer Premise router
                     DS-Lite Dual-Stack Lite
                         IGD Internet Gateway Device
                         IWF Interworking Function
                         NAT Network Address Translation
                         PCP Port Control Protocol
                        UPnP Universal Plug and Play


3.  Architecture Model

   As a reminder, Figure 2 illustrates the architecture model adopted by
   UPnP IGD [IGD2].  In Figure 2, the following UPnP terminology is
   used:

   o  Client refers to a host located in the local network.

   o  IGD Control Point is a UPnP control point using UPnP to control an
      IGD (Internet Gateway Device).

   o  Host represents a remote peer reachable in the Internet.

   +-------------+
   | IGD Control |
   |   Point     |-----+
   +-------------+     |   +-----+       +------+
                       +---|     |       |      |
                           | IGD |-------| Host |
                       +---|     |       |      |
   +-------------+     |   +-----+       +------+
   |   Client    |-----+
   +-------------+


                         Figure 2: UPnP IGD Model

   This model is not valid when PCP is used to control for instance a
   Carrier Grade NAT (a.k.a., Provider NAT) while internal hosts
   continue to use UPnP.  In such scenarios, Figure 3 shows the updated
   model.











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 +-------------+
 | IGD Control |
 |   Point     |-----+
 +-------------+     |   +-----+       +--------+               +------+
                     +---| IGD-|       |Provider|               |      |
                         | PCP |-------|  NAT   |--<Internet>---| Peer |
                     +---| IWF |       |        |               |      |
 +-------------+     |   +-----+       +--------+               +------+
 | Local Host  |-----+
 +-------------+
                       LAN Side  External Side
 <======UPnP IGD===============><======PCP=====>


                 Figure 3: UPnP IGD-PCP Interworking Model

   In the updated model depicted in Figure 3, one or two levels of NAT
   can be encountered in the data path.  Indeed, in addition to the
   Carrier Grade NAT, the CP router may embed a NAT function (Figure 4).

   +-------------+
   | IGD Control |
   |   Point     |-----+
   +-------------+     |   +-----+       +----+               +------+
                       +---| IGD-|       |    |               |Remote|
                           | PCP |-------|NAT2|--<Internet>---| Host |
                       +---| IWF |       |    |               |      |
   +-------------+     |   +-----+       +----+               +------+
   | Local Host  |-----+     NAT1
   +-------------+


                      Figure 4: Cascaded NAT scenario

   To ensure a successful interworking between UPnP IGD and PCP, an
   interworking function is embedded in the CP router.  In the model
   defined in Figure 3, all UPnP IGD server-oriented functions, a PCP
   Client [I-D.ietf-pcp-base] and a UPnP IGD-PCP Interworking Function
   are embedded in the CP router (i.e., IGD).  In the rest of the
   document, IGD-PCP Interworking Function refers to PCP Client and UPnP
   IGD-PCP Interworking Function.

   UPnP IGD-PCP Interworking Function is responsible for generating a
   well-formed PCP (resp., UPnP IGD) message from a received UPnP IGD
   (resp., PCP) message.






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4.  UPnP IGD-PCP Interworking Function: Overview

   Three tables are provided to specify the mapping between UPnP IGD and
   PCP:

   1.  Table 1 provides the mapping between WANIPConnection parameters
       and PCP parameters;

   2.  Table 2 focuses on the correspondence between supported methods;

   3.  Table 3 lists the IGD error messages and their corresponding PCP
       ones.

   Note that some enhancements have been integrated in WANIPConnection
   as documented in [IGD2].

4.1.  UPnP IGD-PCP: Variables

   +---------------------------+------------+--------------------------+
   |      WANIPConnection      |     PCP    |         Comments         |
   +---------------------------+------------+--------------------------+
   |     PortMappingEnabled    |     Not    |    When set to 1, this   |
   |                           | applicable |   parameter MUST NOT be  |
   |                           |            |     reproduced as an     |
   |                           |            |      argument in PCP     |
   |                           |            |  messages.  If set to 0, |
   |                           |            |  this is the default PCP |
   |                           |            |     mode (no explicit    |
   |                           |            |     indication in PCP    |
   |                           |            | messages).  PCP does not |
   |                           |            | support deactivating the |
   |                           |            |    dynamic NAT mapping   |
   |                           |            |  since the initial goal  |
   |                           |            |   of PCP is to ease the  |
   |                           |            |   traversal of Carrier   |
   |                           |            |  Grade NAT.  Supporting  |
   |                           |            |    such per-subscriber   |
   |                           |            |   function may overload  |
   |                           |            |  the Carrier Grade NAT.  |
   +---------------------------+------------+--------------------------+











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   +---------------------------+------------+--------------------------+
   |  PortMappingLeaseDuration |  Requested |  PCP recommends 7200s as |
   |                           |   Mapping  |   default value.  When   |
   |                           |  Lifetime  | PortMappingLeaseDuration |
   |                           |            |  is set to 0, a maximum  |
   |                           |            |   lifetime value MAY be  |
   |                           |            |      included in the     |
   |                           |            |     corresponding PCP    |
   |                           |            | message.  PCP allows for |
   |                           |            | a maximum value of 65536 |
   |                           |            |  seconds while UPnP IGD  |
   |                           |            |   allows 604800 seconds  |
   |                           |            |   (i.e., one week) as a  |
   |                           |            |   maximum bound. 3600s   |
   |                           |            |   being the recommended  |
   |                           |            |    lease value in UPnP   |
   |                           |            |       IGD:2 [IGD2].      |
   +---------------------------+------------+--------------------------+
   |        ExternalPort       |  External  |   PCP does not support   |
   |                           |    Port    |     explicit wildcard    |
   |                           |   Number   | values.  If ExternalPort |
   |                           |            |  is a wildcard value, a  |
   |                           |            | random value of External |
   |                           |            |    Port Number MUST be   |
   |                           |            |      enclosed in the     |
   |                           |            |     corresponding PCP    |
   |                           |            |         message.         |
   +---------------------------+------------+--------------------------+
   |        InternalPort       |  Internal  |                          |
   |                           |    Port    |                          |
   |                           |   Number   |                          |
   +---------------------------+------------+--------------------------+
   |    PortMappingProtocol    |  Transport |   IGD only supports TCP  |
   |                           |  Protocol  |         and UDP.         |
   +---------------------------+------------+--------------------------+
   |       InternalClient      |  Internal  | InternalClient can be an |
   |                           | IP Address |  IP address or a FQDN.   |
   |                           |            |    Only an IP address    |
   |                           |            |  scheme is supported in  |
   |                           |            |  PCP.  If a FQDN is used |
   |                           |            |    by the IGD Control    |
   |                           |            |     Point, it must be    |
   |                           |            |     resolved to an IP    |
   |                           |            |      address by the      |
   |                           |            |   Interworking Function  |
   |                           |            | when relying the message |
   |                           |            |    to the PCP Server.    |
   +---------------------------+------------+--------------------------+



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   +---------------------------+------------+--------------------------+
   |      ExternaIPAddress     |  External  |                          |
   |                           | IP Address |                          |
   +---------------------------+------------+--------------------------+
   |   PortMappingDescription  |     Not    |   Not supported in base  |
   |                           | applicable |   PCP.  When present in  |
   |                           |            |  UPnP IGD messages, this |
   |                           |            |  parameter SHOULD NOT be |
   |                           |            |     propagated in the    |
   |                           |            |     corresponding PCP    |
   |                           |            |  messages.  If the local |
   |                           |            | PCP Client support a PCP |
   |                           |            |   Option to convey the   |
   |                           |            | description, this option |
   |                           |            |       MAY be used.       |
   +---------------------------+------------+--------------------------+
   |         RemoteHost        | REMOTE_PEE |     PCP RECOMMENDS to    |
   |                           | R          |     configure the CP     |
   |                           |            |     router's firewall    |
   |                           |            |  instead of overloading  |
   |                           |            |  the Carrier Grade NAT.  |
   |                           |            |    The REMOTE_PEER PCP   |
   |                           |            |    Option can be used.   |
   +---------------------------+------------+--------------------------+
   |  PossibleConnectionTypes  |     Not    |    Out of scope of PCP   |
   |                           | applicable |                          |
   +---------------------------+------------+--------------------------+
   |      ConnectionStatus     |     Not    |    Out of scope of PCP   |
   |                           | applicable |                          |
   +---------------------------+------------+--------------------------+
   | PortMappingNumberOfEntrie |     Not    |  Managed locally by the  |
   | s                         | applicable |       UPnP IGD-PCP       |
   |                           |            |   Interworking Function  |
   +---------------------------+------------+--------------------------+
   |       SystemUpdateID      |     Not    |  Managed locally by the  |
   |                           | applicable |       UPnP IGD-PCP       |
   |                           |            |   Interworking Function  |
   +---------------------------+------------+--------------------------+

                     Table 1: UPnP IGD-PCP: Variables

4.2.  IGD-PCP: Methods

   Both IGD:1 and IGD:2 methods are listed in Table 2.







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   +-----------------------------+------------+------------------------+
   |       WANIPConnection       |     PCP    |        Comments        |
   +-----------------------------+------------+------------------------+
   |  GetGenericPortMappingEntry |     Not    |   This request is not  |
   |                             | applicable |   relayed to the PCP   |
   |                             |            |    Server.  IGD-PCP    |
   |                             |            |  Interworking Function |
   |                             |            |  maintains an updated  |
   |                             |            |     list of active     |
   |                             |            |  mappings instantiated |
   |                             |            |  in the PCP Server by  |
   |                             |            |  internal hosts.  See  |
   |                             |            |  Section 5.8 for more  |
   |                             |            |      information.      |
   +-----------------------------+------------+------------------------+
   | GetSpecificPortMappingEntry |     Not    |      Under normal      |
   |                             | applicable |     conditions, the    |
   |                             |            |  IGD-PCP Interworking  |
   |                             |            |  Function maintains an |
   |                             |            | updated list of active |
   |                             |            |       mapping as       |
   |                             |            |   instantiated in the  |
   |                             |            |    PCP Server.  The    |
   |                             |            |  IGD-PCP Interworking  |
   |                             |            |    Function locally    |
   |                             |            |  handles this request  |
   |                             |            |  and provides back the |
   |                             |            |   port mapping entry   |
   |                             |            |      based on the      |
   |                             |            |    ExternalPort, the   |
   |                             |            |  PortMappingProtocol,  |
   |                             |            |  and the RemoteHost.   |
   |                             |            |   See Section 5.8 for  |
   |                             |            |    more information    |
   +-----------------------------+------------+------------------------+
   |        AddPortMapping       |    PINxy   |  We recommend the use  |
   |                             |            | of AddAnyPortMapping() |
   |                             |            |       instead of       |
   |                             |            |   AddPortMapping().    |
   |                             |            | Refer to Section 5.7.2 |
   +-----------------------------+------------+------------------------+
   |      DeletePortMapping      | PINxy with |  Refer to Section 5.9  |
   |                             |      a     |                        |
   |                             |  requested |                        |
   |                             |  lifetime  |                        |
   |                             |  set to 0  |                        |
   +-----------------------------+------------+------------------------+




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   +-----------------------------+------------+------------------------+
   |     GetExternalIPAddress    |  PCP does  |                        |
   |                             |     not    |                        |
   |                             |   support  |                        |
   |                             |    yet a   |                        |
   |                             | method for |                        |
   |                             | retrieving |                        |
   |                             |     the    |                        |
   |                             |  external  |                        |
   |                             |     IP     |                        |
   |                             |  address.  |                        |
   |                             |   Issuing  |                        |
   |                             |  PINxy may |                        |
   |                             | be used as |                        |
   |                             | a means to |                        |
   |                             |  retrieve  |                        |
   |                             |     the    |                        |
   |                             |  external  |                        |
   |                             | IP address |                        |
   +-----------------------------+------------+------------------------+
   |   DeletePortMappingRange()  | PINxy with |   Individual requests  |
   |                             | a lifetime |    are issued by the   |
   |                             | positioned |  IGD-PCP Interworking  |
   |                             |    to 0    |   Function.  Refer to  |
   |                             |            |  Section 5.9 for more  |
   |                             |            |         details        |
   +-----------------------------+------------+------------------------+
   |   GetListOfPortMappings()   |     Not    |       The IGD-PCP      |
   |                             | applicable |  Interworking Function |
   |                             |            |  maintains an updated  |
   |                             |            | list of active mapping |
   |                             |            | as instantiated in the |
   |                             |            |    PCP Server.  The    |
   |                             |            |  IGD-PCP Interworking  |
   |                             |            |    Function handles    |
   |                             |            | locally this request.  |
   |                             |            |   See Section 5.8 for  |
   |                             |            |    more information    |
   +-----------------------------+------------+------------------------+
   |     AddAnyPortMapping()     |    PINxy   |       No issue is      |
   |                             |            |  encountered to proxy  |
   |                             |            |   this request to the  |
   |                             |            |  PCP Server.  Refer to |
   |                             |            | Section 5.7.1 for more |
   |                             |            |         details        |
   +-----------------------------+------------+------------------------+

                         Table 2: IGD-PCP: Methods



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4.3.  UPnP IGD-PCP: Errors

   Table 3 lists UPnP IGD errors codes and the corresponding PCP ones.
   Error codes specific to IGD:2 are tagged accordingly.

   +------------------------------------+------------------------------+
   |           IGD Error Code           |        PCP Error Code        |
   +------------------------------------+------------------------------+
   |         401 (InvalidAction)        |      129 (UNSUPP_OPCODE)     |
   +------------------------------------+------------------------------+
   |          402 (InvalidArgs)         |    TBD (MALFORMED_REQUEST)   |
   +------------------------------------+------------------------------+
   |          501(ActionFailed)         |  154 (UNABLE_TO_DELETE_ALL)  |
   |                                    |             (??)             |
   +------------------------------------+------------------------------+
   |   606 (ActionNotAuthorized) (only  |     151 (NOT_AUTHORIZED)     |
   |             for IGD:2)             |                              |
   +------------------------------------+------------------------------+
   |  713 (SpecifiedArrayIndexInvalid)  |  Not applicable because Get* |
   |                                    |  requests are not relayed to |
   |                                    |        the PCP Server        |
   +------------------------------------+------------------------------+
   |      714 (NoSuchEntryInArray)      |     PCP returns always a     |
   |                                    |   positive response even if  |
   |                                    |   the mapping to be deleted  |
   |                                    |  does not exist.  This error |
   |                                    |  code is not applicable for  |
   |                                    |  Get* requests which are not |
   |                                    |   relayed to the PCP Server  |
   +------------------------------------+------------------------------+
   |  715 (WildCardNotPermitedInSrcIP)  |    TBD (MALFORMED_REQUEST)   |
   +------------------------------------+------------------------------+
   |                 716                |        Not applicable        |
   |  (WildCardNotPermitedInSrcExtPort) |                              |
   +------------------------------------+------------------------------+
   |    718 (ConflictInMappingEntry)    |        Not applicable        |
   +------------------------------------+------------------------------+
   |    724 (SamePortValuesRequired)    |        Not applicable        |
   +------------------------------------+------------------------------+
   |  725 (OnlyPermanentLeaseSupported) |        Not applicable        |
   +------------------------------------+------------------------------+
   |                 726                |      130 (UNSUPP_OPTION)     |
   |  (RemoteHostOnlySupportsWildcard)  |                              |
   +------------------------------------+------------------------------+
   |                 727                |        Not applicable        |
   | (ExternalPortOnlySupportsWildcard) |                              |
   +------------------------------------+------------------------------+




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   +------------------------------------+------------------------------+
   |   728 (NoPortMapsAvailable) (only  |    4 (NO_RESOURCES) or 152   |
   |             for IGD:2)             |        (USER_EX_QUOTA)       |
   +------------------------------------+------------------------------+
   |  729 (ConflictWithOtherMechanisms) |   TBD (MECHANISM_CONFLICT)   |
   |          (only for IGD:2)          |                              |
   +------------------------------------+------------------------------+
   |   730 (PortMappingNotFound) (only  |        Not applicable        |
   |             for IGD:2)             |                              |
   +------------------------------------+------------------------------+
   |  732 (WildCardNotPermittedInPort)  |    TBD (MALFORMED_REQUEST)   |
   |          (only for IGD:2)          |                              |
   +------------------------------------+------------------------------+
   |  733 (InconsistentParameter) (only |        Not applicable        |
   |             for IGD:2)             |                              |
   +------------------------------------+------------------------------+

                       Table 3: UPnP IGD-PCP: Errors


5.  Specification of the IGD-PCP Interworking Function

   This section covers the scenarios with or without NAT in the CP
   router.

5.1.  PCP Server Discovery

   The IGD-PCP Interworking Function implements one of the discovery
   methods identified in [I-D.ietf-pcp-base] (e.g., DHCP
   [I-D.bpw-pcp-dhcp]).  The IGD-PCP Interworking Function behaves as a
   PCP Client when communicating with the provisioned PCP Server.

   In order to not impact the delivery of local services requiring the
   control of the local IGD during any failure event to reach the PCP
   Server (e.g., no IP address/prefix is assigned to the CP router),
   IGD-PCP Interworking Function MUST NOT be invoked.  Indeed, UPnP
   machinery is used to control that device and therefore lead to
   successful operations of internal services.

   Once the PCP Sever is reachable, the IGD-PCP Interworking Function
   MUST synchronize its states as specified in Section 5.10.

5.2.  Control of the Firewall

   In order to configure security policies to be applied to inbound and
   outbound traffic, UPnP IGD can be used to control a local firewall
   engine.




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   No IGD-PCP Interworking Function is therefore required for that
   purpose.

5.3.  NAT Control in LAN Side

   Internal UPnP Control Points are not aware of the presence of the
   IGD-PCP Interworking Function in the CP router (IGD).  Especially,
   UPnP Control Points MUST NOT be aware of the deactivation of the NAT
   in the CP router.

   No modification is required in the UPnP Control Point.

5.4.  Port Mapping Tables

   IGD-PCP Interworking Function MUST store locally all the mappings
   instantiated by internal UPnP Control Points in the PCP Server.  Port
   Forwarding mappings SHOULD be stored in a permanent storage.  If not,
   upon reset or reboot, the IGD-PCP Interworking Function MUST
   synchronise its states as specified in Section 5.10.

   Upon receipt of a PCP PINxy Response from the PCP Server, the IGD-PCP
   Interworking Function MUST retrieve the enclosed mapping(s) and MUST
   store it in the local mapping table.  The local mapping table is an
   image of the mapping table as maintained by the PCP Server for a
   given subscriber.

5.5.  Interworking Function Without NAT in the CP Router

   When no NAT is embedded in the CP router, the content of received
   WANIPConnection and PCP messages is not altered by the IGD-PCP
   Interworking Function (i.e., the content of WANIPConnection messages
   are copied to the PCP messages (and vice versa) according to
   Table 1).

5.6.  NAT Embedded in the CP Router

   Unlike the scenario with one level of NAT (Section 5.5), the IGD-PCP
   Interworking Function MUST update their content of received mapping
   messages with the IP address and/or port number belonging to the
   external interface of the CP router (i.e., after the NAT1 operation
   in Figure 4) and not as initially positioned by the UPnP Control
   Point.

   All WANIPConnection messages issued by the UPnP Control Point (resp.,
   PCP Server) are intercepted by the IGD-PCP Interworking Function.
   Then, the corresponding messages (see Table 1, Table 2 and Table 3)
   are generated by the IGD-PCP Interworking Function and sent to the
   provisioned PCP Server (resp., corresponding UPnP Control Point).



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   The content of PCP messages received by the PCP Server reflects the
   mapping information as enforced in the first NAT.  In particular, the
   internal IP address and/or port number of the requests are replaced
   with the IP address and port number as assigned by the NAT of the CP
   router.  For the reverse path, PCP response messages are intercepted
   by the IGD-PCP Interworking Function.  The content of the
   corresponding WANIPConnection messages are updated:

   o  The internal IP address and/or port number as initially positioned
      by the UPnP Control Point and stored in the CP router NAT are used
      to update the corresponding fields in received PCP responses.

   o  The external IP and port number are not altered by the IGD-PCP
      Interworking Function.

   o  The NAT mapping entry in the first NAT is updated with the result
      of PCP request.

   The lifetime of the mappings instantiated in all involved NATs SHOULD
   be the one assigned by the terminating PCP Server.  In any case, the
   lifetime MUST be lower or equal to the one assigned by the
   terminating PCP Server.

5.7.  Creating a Mapping

   Two methods can be used to create a mapping: AddPortMapping() or
   AddAnyPortMapping().

   AddAnyPortMapping() is the RECOMMENDED method.

5.7.1.  AddAnyPortMapping()

   When an UPnP Control Point issues a AddAnyPortMapping(), this request
   is received by the UPnP Server.  The request is then relayed to the
   IGD-PCP Interworking Function which generates a PCP PINxy Request
   (see Table 1 for mapping between WANIPConnection and PCP parameters).
   Upon receipt of PCP PINxy Response from the PCP Server, an XML
   mapping is returned to the requesting UPnP Control Point (the content
   of the messages follows the recommendations listed in Section 5.6 or
   Section 5.5 according to the deployed scenario).  A flow example is
   depicted in Figure 5.

   If a PCP Error is received from the PCP Server, a corresponding
   WANIPConnection error code Table 3 is generated by the IGD-PCP
   Interworking Function and sent to the requesting UPnP Control Point.






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                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                    PCP Server
        |                      |                             |
        |(1) AddAnyPortMapping |                             |
        |--------------------->|                             |
        |                      |   (2) PCP PINxy Request     |
        |                      |(requested external port=0)  |
        |                      |---------------------------->|
        |                      |                             |
        |                      |   (3) PCP PINxy Response    |
        |                      |(assigned external port=6598)|
        |                      |<----------------------------|
        |(4) AddAnyPortMapping |                             |
        |   ReservedPort=6598  |                             |
        |<---------------------|                             |


          Figure 5: Flow example when AddAnyPortMapping() is used

5.7.2.  AddPortMapping()

   A dedicated option called HONOR_EXTERNAL_PORT is defined in
   [I-D.ietf-pcp-base] to toggle the behavior in a PCP Request message.
   This options is inserted by the IGD-PCP IWF when issuing its requests
   to the PCP Server only if a specific external port is requested by
   the UPnP Control Point.  When a wildcard is used (i.e., 0),
   HONOR_EXTERNAL_PORT Option is not required to be inserted in the PCP
   request to the PCP Server (see Figure 6).  In the remaining, we
   assume that a specific external port is requested by the UPnP Control
   Point.




















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                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                   PCP Server
        |                      |                             |
        | (1) AddPortMapping   |                             |
        |   ExternalPort=0     |                             |
        |--------------------->|                             |
        |                      |   (2) PCP PINxy Request     |
        |                      |(requested external port=0)  |
        |                      |---------------------------->|
        |                      |                             |
        |                      |   (3) PCP PINxy Response    |
        |                      |(assigned external port=1365)|
        |                      |<----------------------------|
        |  (4) AddPortMapping  |                             |
        |   ExternalPort=1356  |                             |
        |<---------------------|                             |


     Figure 6: Example of AddPortMapping() with wildcard external port

   Upon receipt of AddPortMapping() from an UPnP Control Point, the IGD-
   PCP Interworking Function first checks if the requested external port
   number is not used by another Internal UPnP Control Point.  In case a
   mapping bound to the requested external port number is found in the
   local mapping table, the IGD-PCP IWF MUST send back a
   ConflictInMappingEntry error to the requesting UPnP Control Point
   (see Figure 7).























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                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                  PCP Server
        |                      |                           |
        | (1) AddPortMapping   |                           |
        |   ExternalPort=2356  |                           |
        |--------------------->|                           |
        |                      |                           |
        |     (2) Error:       |                           |
        |ConflictInMappingEntry|                           |
        |<---------------------|                           |
        |                      |                           |
        | (3) AddPortMapping   |                           |
        |   ExternalPort=4586  |                           |
        |--------------------->|                           |
        |                      |                           |
        |     (4) Error:       |                           |
        |ConflictInMappingEntry|                           |
        |<---------------------|                           |
        |                      |                           |


                       Figure 7: IWF Local Behaviour

   This exchange (Figure 7) is re-iterated until an external port number
   that is not in use is requested by the UPnP Control Point.  Then, the
   IGD-PCP IWF generates a PCP PINxy Request with all requested mapping
   information as indicated by the UPnP Control Point if no NAT is
   embedded in the CP router or updated as specified in Section 5.6.  In
   addition, the IGD-PCP IWF inserts a HONOR_EXTERNAL_PORT Option to the
   generated PCP request.

   If the requested external port is in use, a PCP Error message MUST be
   sent by the PCP Server to the IGD-PCP IWF indicating
   CANNOT_HONOR_EXTERNAL_PORT as the error cause.  The IGD-PCP IWF
   relays a negative message to the UPnP Control Point indicating
   ConflictInMappingEntry as error code.  The UPnP Control Point re-
   issues a new request with a new requested external port number.  This
   process is repeated until a positive answer is received or maximum
   retry is reached.

   If the PCP Server is able to honor the requested external port, a
   positive response is sent to the requesting IGD-PCP IWF.  Upon
   receipt of the response from the PCP Server, the returned mapping
   MUST be stored by the IGD-PCP Interworking Function in its local
   mapping table and a positive answer MUST be sent to the requesting
   UPnP Control Point.  This answer terminates this exchange.




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   Figure 8 shows an example of the flow exchange that occurs when the
   PCP Server satisfies the request from the IGD-PCP IWF.  Figure 9
   shows the messages exchange when the requested external port is in
   use.

                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                  PCP Server
        |                      |                             |
        | (1) AddPortMapping   |                             |
        |   ExternalPort=8080  |                             |
        |--------------------->|                             |
        |                      |   (2) PCP PINxy Request     |
        |                      |requested external port=8080 |
        |                      |     HONOR_EXTERNAL_PORT     |
        |                      |---------------------------->|
        |                      |                             |
        |                      |   (3) PCP PINxy Response    |
        |                      | assigned external port=8080 |
        |                      |<----------------------------|
        | (4) AddPortMapping   |                             |
        |   ExternalPort=8080  |                             |
        |<---------------------|                             |


                 Figure 8: Flow Example (Positive Answer)

























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                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                    PCP Server
        |                      |                             |
        | (1) AddPortMapping   |                             |
        |   ExternalPort=8080  |                             |
        |--------------------->|                             |
        |                      |   (2) PCP PINxy Request     |
        |                      |requested external port=8080 |
        |                      |     HONOR_EXTERNAL_PORT     |
        |                      |---------------------------->|
        |                      |   (3) PCP PINxy Response    |
        |                      | CANNOT_HONOR_EXTERNAL_PORT  |
        |                      |<----------------------------|
        |     (4) Error:       |                             |
        |ConflictInMappingEntry|                             |
        |<---------------------|                             |
        | (5) AddPortMapping   |                             |
        |   ExternalPort=5485  |                             |
        |--------------------->|                             |
        |                      |   (6) PCP PINxy Request     |
        |                      |requested external port=5485 |
        |                      |     HONOR_EXTERNAL_PORT     |
        |                      |---------------------------->|
        |                      |   (7) PCP PINxy Response    |
        |                      | CANNOT_HONOR_EXTERNAL_PORT  |
        |                      |<----------------------------|
        |     (8) Error:       |                             |
        |ConflictInMappingEntry|                             |
        |<---------------------|                             |
                               ....
        | (a) AddPortMapping   |                             |
        |   ExternalPort=6591  |                             |
        |--------------------->|                             |
        |                      |   (b) PCP PINxy Request     |
        |                      |requested external port=6591 |
        |                      |     HONOR_EXTERNAL_PORT     |
        |                      |---------------------------->|
        |                      |   (c) PCP PINxy Response    |
        |                      | CANNOT_HONOR_EXTERNAL_PORT  |
        |                      |<----------------------------|
        |     (d) Error:       |                             |
        |ConflictInMappingEntry|                             |
        |<---------------------|                             |


                 Figure 9: Flow Example (Negative Answer)




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5.8.  Listing One or a Set of Mappings

   In order to list active mappings, an UPnP Control Point may issue
   GetGenericPortMappingEntry(), GetSpecificPortMappingEntry() or
   GetListOfPortMappings().

   These methods MUST NOT be proxied to the PCP Server since a local
   mapping is maintained by the IGD-PCP Interworking Function.

5.9.  Delete One or a Set of Mappings: DeletePortMapping() or
      DeletePortMappingRange()

   An UPnP Control Point proceeds to the deletion of one or a list of
   mappings by issuing DeletePortMapping() or DeletePortMappingRange().
   When one of these messages is received by the IGD-PCP Interworking
   Function, it first checks if the requested mapping to be removed is
   present in the local mapping table.  If no mapping matching the
   request is found in the local table, an error is sent back to the
   UPnP Control Point (see Figure 10).

                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                  PCP Server
        |                      |                           |
        |(1) DeletePortMapping |                           |
        |--------------------->|                           |
        |                      |                           |
        |     (2) Error:       |                           |
        |  NoSuchEntryInArray  |                           |
        |<---------------------|                           |
        |                      |                           |


                   Figure 10: Local Delete (IGD-PCP IWF)

   if a mapping matches in the local table, PCP PINxy delete request(s)
   is generated taking into account the input arguments:

   o  as included in DeletePortMapping() if no NAT is enabled in the CP
      router; In case DeletePortMappingRange() is used, the IGD-PCP IWF
      generates individual requests to cover all the range;

         [[Note: Add a figure to illustrate the behaviour to handle
         DeletePortMappingRange()]]

   o  or the corresponding local IP address and port number as assigned
      by the local NAT if a NAT is enabled in the CP router.




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   Once received by the PCP Server, it proceeds to removing the
   corresponding entry(ies).  A PCP PINxy delete response is sent back
   if the removal of the corresponding entry(ies) was successful; if
   not, a PCP Error is sent back to the IGD-PCP Interworking Function
   including the corresponding error cause (e.g., Not Authorised).

   When a positive answer is received from the PCP Server, the IGD-PCP
   Interworking Function updates its local mapping table (i.e., remove
   the corresponding entry(ies)) and notifies the UPnP Control Point
   about the result of the removal operation.

5.10.  Mapping Synchronisation

   [[Note: This section needs further discussion among authors]]

   Under normal conditions, since a valid copy of the mapping table is
   stored locally in the CP router, the IGD-PCP Interworking Function
   SHOULD NOT issue any subsequent PCP request to handle a request
   received from an UPnP Control Point to list active mappings.
   Nevertheless, in case of loss of synchronisation (e.g., reboot,
   system crashes, power outage, etc.), the IGD-PCP Interworking
   Function SHOULD generate a get method to retrieve all active mappings
   in the PCP Server and update its local mapping table without waiting
   for an explicit request from a UPnP Control Point.  Doing so, the
   IGD-PCP Interworking Function maintains an updated mapping table.

   In case of massive reboot of CP routers (e.g., avalanche restart
   phenomenon), PCP request bursts SHOULD be avoided.  For this aim, we
   recommend the use of a given timer denoted as PCP_SERVICE_WAIT.  This
   timer can be pre-configured in the CP router or to be provisioned
   using a dedicated means such as DHCP.  Upon reboot of the CP router,
   PCP messages SHOULD NOT be sent immediately.  A random value is
   selected between 0 and PCP_SERVICE_WAIT.  This value is referred to
   as RAND(PCP_SERVICE_WAIT).  Upon the expiration of
   RAND(PCP_SERVICE_WAIT), the CP router SHOULD proceed to its
   synchronisation operations (i.e., retrieve all active mappings which
   have been instructed by internal UPnP Control Point(s)).

   [[Note: per-subscriber quota may be exhausted due to unlimited
   lifetime and stale mappings in IGD due to reboots, etc.]]


6.  IANA Considerations

   This document makes no request of IANA.

   Note to RFC Editor: this section may be removed on publication as an
   RFC.



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7.  Security Considerations

   This document defines a procedure to instruct PCP mappings for third
   party devices belonging to the same subscriber.  Identification means
   to avoid a malicious user to instruct mappings on behalf of a third
   party must be enabled.  Such means are already discussed in Section
   7.4.4 of [I-D.ietf-pcp-base].

   Security considerations elaborated in [I-D.ietf-pcp-base] and
   [Sec_DCP] should be taken into account.


8.  Acknowledgments

   Authors would like to thank F. Fontaine and C. Jacquenet for their
   review and comments.


9.  References

9.1.  Normative References

   [I-D.ietf-pcp-base]
              Wing, D., "Port Control Protocol (PCP)",
              draft-ietf-pcp-base-01 (work in progress), December 2010.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

9.2.  Informative References

   [I-D.bpw-pcp-dhcp]
              Boucadair, M., Penno, R., and D. Wing, "DHCP and DHCPv6
              Options for Port Control Protocol (PCP)",
              draft-bpw-pcp-dhcp-00 (work in progress), October 2010.

   [I-D.ietf-behave-v6v4-xlate-stateful]
              Bagnulo, M., Matthews, P., and I. Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers",
              draft-ietf-behave-v6v4-xlate-stateful-12 (work in
              progress), July 2010.

   [I-D.ietf-softwire-dual-stack-lite]
              Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", draft-ietf-softwire-dual-stack-lite-06 (work
              in progress), August 2010.



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   [IGD2]     UPnP Forum, "WANIPConnection:2 Service (http://upnp.org/
              specs/gw/UPnP-gw-WANIPConnection-v2-Service.pdf)",
              September 2010.

   [Sec_DCP]  UPnP Forum, "Device Protection:1", November 2009.


Authors' Addresses

   Mohamed Boucadair
   France Telecom
   Rennes,   35000
   France

   Email: mohamed.boucadair@orange-ftgroup.com


   Reinaldo Penno
   Juniper Networks
   1194 N Mathilda Avenue
   Sunnyvale, California  94089
   USA

   Email: rpenno@juniper.net


   Dan Wing
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, California  95134
   USA

   Email: dwing@cisco.com


   Francis Dupont
   ISC

   Email: Francis.Dupont@fdupont.fr












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