[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-bpw-pcp-upnp-igd-interworking) 00 01 02 03 04 05 06 08 09 10 RFC 6970

PCP Working Group                                           M. Boucadair
Internet-Draft                                            France Telecom
Intended status: Standards Track                                R. Penno
Expires: October 26, 2013                                        D. Wing
                                                                   Cisco
                                                          April 24, 2013


   Universal Plug and Play (UPnP) Internet Gateway Device (IGD)-Port
              Control Protocol (PCP) Interworking Function
                draft-ietf-pcp-upnp-igd-interworking-09

Abstract

   This document specifies the behavior of the UPnP IGD (Internet
   Gateway Device)/PCP Interworking Function.  A UPnP IGD-PCP
   Interworking Function (IGD-PCP IWF) is required to be embedded in CP
   (Customer Premises) routers to allow for transparent NAT control in
   environments where UPnP IGD is used on the LAN side and PCP on 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 October 26, 2013.

Copyright Notice

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



Boucadair, et al.       Expires October 26, 2013                [Page 1]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Acronyms  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Architecture Model  . . . . . . . . . . . . . . . . . . . . .   4
   4.  UPnP IGD-PCP IWF: Overview  . . . . . . . . . . . . . . . . .   5
     4.1.  UPnP IGD-PCP: State Variables . . . . . . . . . . . . . .   6
     4.2.  IGD-PCP: Methods  . . . . . . . . . . . . . . . . . . . .   7
     4.3.  UPnP IGD-PCP: Errors  . . . . . . . . . . . . . . . . . .   8
   5.  Specification of the IGD-PCP IWF  . . . . . . . . . . . . . .   9
     5.1.  PCP Server Discovery  . . . . . . . . . . . . . . . . . .   9
     5.2.  Control of the Firewall . . . . . . . . . . . . . . . . .   9
     5.3.  Port Mapping Table  . . . . . . . . . . . . . . . . . . .  10
     5.4.  Interworking Function Without NAT in the IGD  . . . . . .  10
     5.5.  NAT Embedded in the IGD . . . . . . . . . . . . . . . . .  10
     5.6.  Creating a Mapping  . . . . . . . . . . . . . . . . . . .  11
       5.6.1.  AddAnyPortMapping() . . . . . . . . . . . . . . . . .  11
       5.6.2.  AddPortMapping()  . . . . . . . . . . . . . . . . . .  12
     5.7.  Listing One or a Set of Mappings  . . . . . . . . . . . .  15
     5.8.  Delete One or a Set of Mappings: DeletePortMapping() or
           DeletePortMappingRange()  . . . . . . . . . . . . . . . .  15
     5.9.  Renewing a Mapping  . . . . . . . . . . . . . . . . . . .  18
     5.10. Rapid Recovery  . . . . . . . . . . . . . . . . . . . . .  19
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  20
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  20
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  20
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  21
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Introduction

   PCP [I-D.ietf-pcp-base] discusses the implementation of NAT control
   features that rely upon Carrier Grade NAT devices such as a DS-Lite
   AFTR [RFC6333] or NAT64 [RFC6146].  Nevertheless, in environments
   where UPnP IGD (Internet Gateway Device) is used in the local
   network, an interworking function between UPnP IGD and PCP is



Boucadair, et al.       Expires October 26, 2013                [Page 2]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   required to be embedded in the IGD (see the example illustrated in
   Figure 1).

   Two configurations are considered:

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

   o  The IGD embeds a NAT function.

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

                          Figure 1: Flow Example

   The UPnP IGD-PCP Interworking Function (UPnP IGD-PCP IWF) maintains a
   local mapping table that stores all active mappings constructed 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 IWF from the IGD and
   relying on a PCP-only mode are out of scope of this document.

   Considerations related to co-existence of the UPnP IGD-PCP
   Interworking Function and a PCP Proxy [I-D.ietf-pcp-proxy] are out of
   scope.

2.  Acronyms

   This document makes use of the following abbreviations:

      DS-Lite - Dual-Stack Lite
      IGD - Internet Gateway Device
      IGD:1 - UPnP Forum's nomenclature for version 1 of IGD [IGD1]
      IGD:2 - UPnP Forum's nomenclature for version 2 of IGD [IGD2]
      IWF - Interworking Function
      NAT - Network Address Translation
      PCP - Port Control Protocol
      UPnP - Universal Plug and Play




Boucadair, et al.       Expires October 26, 2013                [Page 3]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


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 device using UPnP to control an IGD
      (Internet Gateway Device).

   o  'IGD' is a router supporting UPnP IGD.  It is typically a NAT or a
      firewall.

   o  'Host' is 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 IGD.  In such scenarios, Figure 3 shows the
   updated model.

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




Boucadair, et al.       Expires October 26, 2013                [Page 4]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


                 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 IGD 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 successful interworking between UPnP IGD and PCP, an
   interworking function is embedded in the IGD.  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 IGD.  In the rest of the document, IGD-PCP IWF refers
   the UPnP IGD-PCP Interworking Function, which includes PCP Client
   functionality.

   Without the involvement of the IGD-PCP IWF, the UPnP Control Point
   would retrieve an external IP address and port number having a
   limited scope and which cannot be used to communicate with hosts
   located beyond NAT2 (i.e., assigned by the IGD and not the ones
   assigned by NAT2 in Figure 4).

   UPnP IGD-PCP IWF is responsible for generating a well-formed PCP
   message from a received UPnP IGD message, and vice versa.

4.  UPnP IGD-PCP IWF: Overview

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

   (1)  Section 4.1 provides the mapping between WANIPConnection State
      Variables and PCP parameters;

   (2)  Section 4.2 focuses on the correspondence between supported
      methods;




Boucadair, et al.       Expires October 26, 2013                [Page 5]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   (3)  Section 4.3 lists the PCP error messages and their corresponding
      IGD ones.

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

4.1.  UPnP IGD-PCP: State Variables

   Below are listed only the UPnP IGD state variables applicable to the
   IGD-PCP IWF:

   ExternalIPAddress:  External IP Address
      Read-only variable with the value from the last PCP response or
      the empty string if none was received yet.  This state is stored
      on a per UPnP Control Point basis.

   PortMappingNumberOfEntries:  Managed locally by the UPnP IGD-PCP IWF.

   PortMappingEnabled:
      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.
      Only "1" is allowed: i.e., the UPnP IGD-PCP Interworking Function
      MUST send back an error if a value different from 1 is signaled.

   PortMappingLeaseDuration:  Requested Mapping Lifetime
      In IGD:1 [IGD1] the value 0 means infinite, in IGD:2 it is
      remapped to the IGD maximum of 604800 seconds [IGD2].  PCP allows
      for a maximum value of 4294967296 seconds.
      The UPnP IGD-PCP Interworking Function simulates long and even
      infinite lifetimes using renewals (see Section 5.9).  The behavior
      of the UPnP IGD-PCP IWF in the case of a failing renewal is
      currently undefined (see Section 5.9).
      IGD:1 doesn't define the behavior in the case of state loss, IGD:2
      doesn't require to keep state in stable storage, i.e., to allow
      the state to survive resets/reboots.  The UPnP IGD-PCP
      Interworking Function MUST support IGD:2 behavior.

   RemoteHost:  Remote Peer IP Address
      Note that IGD:2 allows a domain name, which has to be resolved to
      an IP address.

   ExternalPort:  External Port Number
      Mapped to the Suggested External Port in MAP messages.

   InternalPort:  Internal Port Number
      Mapped to the Internal Port field in MAP messages.



Boucadair, et al.       Expires October 26, 2013                [Page 6]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   PortMappingProtocol:  Transport Protocol
      Mapped to the Protocol field in MAP messages.  Note that UPnP IGD
      only supports TCP and UDP.

   InternalClient:  Internal IP Address
      Note that IGD:2 allows a domain name, which has to be resolved to
      an IP address.

   PortMappingDescription:  Not supported in base PCP.
      If the local PCP Client supports a PCP Option to convey the
      description (e.g., [I-D.ietf-pcp-description-option]), this option
      SHOULD be used to relay the mapping description.

   SystemUpdateID (IGD:2 only):  Managed locally by the UPnP IGD-PCP
      IWF.

   A_ARG_TYPE_PortListing (IGD:2 only):  Managed locally by the UPnP
      IGD-PCP IWF.

4.2.  IGD-PCP: Methods

   Both IGD:1 and IGD:2 methods applicable to the UPnP IGD-PCP
   Interworking Function are listed here.

   GetGenericPortMappingEntry:  This request is not relayed to the PCP
      Server.
      IGD-PCP Interworking Function maintains a list of active mappings
      instantiated in the PCP Server by internal hosts.  See Section 5.7
      for more information.

   GetSpecificPortMappingEntry:  MAP with PREFER_FAILURE Option
      This request is relayed to the PCP Server by issuing a MAP request
      with the PREFER_FAILURE Option.  It is RECOMMENDED to use a short
      lifetime (e.g., 60 seconds).

   AddPortMapping:  MAP
      See Section 5.6.2.

   AddAnyPortMapping (IGD:2 only):  MAP
      See Section 5.6.1.

   DeletePortMapping:  MAP with Requested Lifetime set to 0.
      See Section 5.8.

   DeletePortMappingRange (IGD:2 only):  MAP with Requested Lifetime set
      to 0.
      Individual requests are issued by the IGD-PCP IWF.  See
      Section 5.8 for more details.



Boucadair, et al.       Expires October 26, 2013                [Page 7]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   GetExternalIPAddress:  MAP
      This can be learned from any active mapping.  If there are no
      active mappings, the IGD-PCP IWF MAY request a short-lived mapping
      (e.g., to the Discard service (TCP/9 or UDP/9) or some other
      port).  However, once that mapping expires a subsequent implicit
      or explicit dynamic mapping might be mapped to a different
      external IP address.  See section 11.6 of [I-D.ietf-pcp-base] for
      more discussion.

   GetListOfPortMappings:  See Section 5.7 for more information.
      The IGD-PCP Interworking Function maintains a list of active
      mappings instantiated in the PCP Server.  The IGD-PCP Interworking
      Function handles this request locally.

4.3.  UPnP IGD-PCP: Errors

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

   1 UNSUPP_VERSION:  501 "ActionFailed"

   2 NOT_AUTHORIZED:  IGD:1 718 "ConflictInMappingEntry" / IGD:2 606
      "Action not authorized"

   3 MALFORMED_REQUEST:  501 "ActionFailed"

   4 UNSUPP_OPCODE:  501 "ActionFailed"
      [I-D.ietf-pcp-base] allows the PCP server to be configured to
      disable support for the MAP opcode, but the IGD-PCP IWF cannot
      work in this situation.

   5 UNSUPP_OPTION:  501 "ActionFailed"
      This error code can be received if PREFER_FAILURE is not supported
      on the PCP server.  Note that PREFER_FAILURE is not mandatory to
      support, but AddPortMapping() cannot be implemented without it.

   6 MALFORMED_OPTION:  501 "ActionFailed"

   7 NETWORK_FAILURE:  501 "ActionFailed"

   8 NO_RESOURCES:  IGD:1 501 "ActionFailed" / IGD:2 728
      "NoPortMapsAvailable"
      Cannot be distinguished from USER_EX_QUOTA.

   9 UNSUPP_PROTOCOL:  501 "ActionFailed"

   10 USER_EX_QUOTA:  IGD:1 501 "ActionFailed" / IGD:2 728
      "NoPortMapsAvailable"



Boucadair, et al.       Expires October 26, 2013                [Page 8]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


      Cannot be distinguished from NO_RESOURCES.

   11 CANNOT_PROVIDE_EXTERNAL:  718 "ConflictInMappingEntry" (see
      Section 5.7.2) or 714 "NoSuchEntryInArray" (see Section 5.8).

   12 ADDRESS_MISMATCH:  501 "ActionFailed"

   13 EXCESSIVE_REMOTE_PEERS:  501 "ActionFailed"
      Note IGD-PCP Interworking Function does not use the FILTER option.

5.  Specification of the IGD-PCP IWF

   This section covers the scenarios with or without NAT in the IGD.

   This specification assumes the PCP Server is configured to accept the
   MAP OpCode.

   The IGD-PCP IWF handles the "Mapping Nonce" the same way as any PCP
   Client [I-D.ietf-pcp-base].

5.1.  PCP Server Discovery

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

   If no IPv4 address / IPv6 prefix is assigned to the IGD or the IGD is
   unable to determine whether it should contact an upstream PCP Server,
   the IGD-PCP Interworking Function MUST NOT be invoked.

   If the IGD determines that it should establish communication with an
   upstream PCP server (e.g., because of DHCP configuration or having
   previously been talking to a PCP server), a "501 ActionFailed" error
   message is returned to the requesting UPnP Control Point in case the
   IGD-PCP IWF fails to establish communication with that PCP Server.
   Note, the IGD-PCP IWF proceeds to PCP messages validation and
   retransmission the same way as any PCP Client [I-D.ietf-pcp-base].

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.  No IGD-PCP IWF is therefore required for that purpose.

   The use of IGD-PCP IWF to control an upstream PCP-controlled firewall
   is out of scope of this document.




Boucadair, et al.       Expires October 26, 2013                [Page 9]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


5.3.  Port Mapping Table

   The IGD-PCP IWF MUST store locally all the mappings instantiated by
   internal UPnP Control Points in the PCP Server.  All mappings SHOULD
   be stored in permanent storage.

   Upon receipt of a PCP MAP Response from the PCP Server, the IGD-PCP
   Interworking Function MUST extract the enclosed mapping 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.

5.4.  Interworking Function Without NAT in the IGD

   When no NAT is embedded in the IGD, 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 mapped to PCP messages (and mapped back) according to
   Section 4.1).

5.5.  NAT Embedded in the IGD

   When NAT is embedded in the IGD, the IGD-PCP IWF updates the content
   of mapping messages received from the UPnP Control Point.  These
   messages will contain an IP address and/or port number which belong
   to an internal host.  The IGD-PCP IWF MUST update such messages with
   the IP address and/or port number belonging to the external interface
   of the IGD (i.e., after the NAT1 operation in Figure 4).

   The IGD-PCP IWF intercepts all WANIPConnection messages issued by the
   UPnP Control Point.  For each such message, the IGD-PCP IWF then
   generates one or more corresponding requests (see Section 4.1,
   Section 4.2 and Section 4.3) and sends them to the provisioned PCP
   Server.

   Each request sent by the IGD-PCP IWF to the PCP Server MUST reflect
   the mapping information as enforced in the first NAT.  Particularly,
   the internal IP address and/or port number of the requests are
   replaced with the IP address and/or port number as assigned by the
   NAT of the IGD.  For the reverse path, the IGD-PCP IWF intercepts PCP
   response messages and generates WANIPConnection response messages.
   The content of the generated WANIPConnection response messages are
   set as follows:

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




Boucadair, et al.       Expires October 26, 2013               [Page 10]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


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

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

   The lifetime of the mappings instantiated in the IGD SHOULD be the
   one assigned by the terminating PCP Server.  In any case, the
   lifetime MUST NOT be lower than the one assigned by the terminating
   PCP Server.

5.6.  Creating a Mapping

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

5.6.1.  AddAnyPortMapping()

   When a UPnP Control Point issues an AddAnyPortMapping(), this request
   is received by the IGD.  The request is then relayed to the IGD-PCP
   IWF which generates a PCP MAP request (see Section 4.1 for mapping
   between WANIPConnection and PCP parameters).

   If the IGD-PCP IWF fails to send the MAP request to its PCP Server,
   it follows the behavior defined in Section 5.1.

   Upon receipt of a PCP MAP response from the PCP Server, the
   corresponding UPnP IGD method is returned to the requesting UPnP
   Control Point (the content of the messages follows the
   recommendations listed in Section 5.5 or Section 5.4 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 (see Section 4.3) is generated by the IGD-
   PCP IWF and sent to the requesting UPnP Control Point.  If a short
   lifetime error is returned (e.g., NETWORK_FAILURE, NO_RESOURCES), the
   PCP IWF MAY resend the same request to the PCP Server after 30
   seconds.  If a negative answer is received, the error is then relayed
   to the requesting UPnP Control Point.

      Discussion: Some applications (e.g., uTorrent, Vuze, eMule) wait
      90 seconds or more for a response after sending an UPnP request.
      If a short lifetime error occurs, resending the request may lead
      to a positive response from the PCP server.  UPnP Control Points
      are therefore not aware of transient errors.

                            UPnP-PCP
   UPnP Control           Interworking



Boucadair, et al.       Expires October 26, 2013               [Page 11]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


      Point                 Function                    PCP Server
        |                      |                             |
        |(1) AddAnyPortMapping |                             |
        |   ExternalPort=8080  |                             |
        |--------------------->|                             |
        |                      |   (2) PCP MAP Request       |
        |                      |Suggested External Port=8080 |
        |                      |---------------------------->|
        |                      |                             |
        |                      |   (3) PCP MAP Response      |
        |                      | Assigned External Port=6598 |
        |                      |<----------------------------|
        |(4) AddAnyPortMapping |                             |
        |   ReservedPort=6598  |                             |
        |<---------------------|                             |


          Figure 5: Flow example when AddAnyPortMapping() is used

5.6.2.  AddPortMapping()

   A dedicated option called PREFER_FAILURE is defined in
   [I-D.ietf-pcp-base] to toggle the behavior in a PCP Request message.
   This option 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.

   Upon receipt of AddPortMapping() from an UPnP Control Point, the IGD-
   PCP IWF MUST generate a PCP MAP Request with all requested mapping
   information as indicated by the UPnP Control Point if no NAT is
   embedded in the IGD or updated as specified in Section 5.5.  In
   addition, the IGD-PCP IWF MUST insert a PREFER_FAILURE Option in the
   generated PCP request.

   If the IGD-PCP IWF fails to send the MAP request to its PCP Server,
   it follows the behavior defined in Section 5.1.

   If the requested external port is not available, the PCP server will
   send a CANNOT_PROVIDE_EXTERNAL error response:

   1.  If a short lifetime error is returned, the IGD-PCP IWF MAY resend
       the same request to the PCP Server after 30 seconds without
       relaying the error to the UPnP Control Point.  The IGD-PCP IWF
       MAY repeat this process until a positive answer is received or
       some maximum retry limit is reached.  When the maximum retry
       limit is reached, the IGD-PCP IWF relays a negative message to
       the UPnP Control Point with ConflictInMappingEntry as the error
       code.  The maximum retry limit is implementation-specific.



Boucadair, et al.       Expires October 26, 2013               [Page 12]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   2.  If a long lifetime error is returned, the IGD-PCP IWF relays a
       negative message to the UPnP Control Point with
       ConflictInMappingEntry as the error code.

   The UPnP Control Point may issue a new request with a different
   requested external port number.  This process is typically repeated
   by the UPnP Control Point until a positive answer is received or some
   maximum retry limit is reached.

   If the PCP Server is able to create or renew a mapping with the
   requested external port, it sends a positive response to the IGD-PCP
   IWF.  Upon receipt of the response from the PCP Server, the IGD-PCP
   IWF stores the returned mapping in its local mapping table, and sends
   the corresponding positive answer to the requesting UPnP Control
   Point.  This answer terminates this exchange.

   Figure 6 shows an example of the flow exchange that occurs when the
   PCP Server satisfies the request from the IGD-PCP IWF.  Figure 7
   shows the messages exchange when the requested external port is not
   available.

                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                  PCP Server
        |                      |                             |
        | (1) AddPortMapping   |                             |
        |   ExternalPort=8080  |                             |
        |--------------------->|                             |
        |                      |   (2) PCP MAP request       |
        |                      |Suggested External Port=8080 |
        |                      |       PREFER_FAILURE        |
        |                      |---------------------------->|
        |                      |                             |
        |                      |   (3) PCP MAP response      |
        |                      | Assigned External Port=8080 |
        |                      |<----------------------------|
        | (4) AddPortMapping   |                             |
        |   ExternalPort=8080  |                             |
        |<---------------------|                             |


                 Figure 6: Flow Example (Positive Answer)

                            UPnP-PCP
   UPnP Control           Interworking
      Point                 Function                    PCP Server
        |                      |                             |
        | (1) AddPortMapping   |                             |



Boucadair, et al.       Expires October 26, 2013               [Page 13]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


        |   ExternalPort=8080  |                             |
        |--------------------->|                             |
        |                      |   (2) PCP MAP Request       |
        |                      |Suggested External Port=8080 |
        |                      |       PREFER_FAILURE        |
        |                      |---------------------------->|
        |                      |   (3) PCP MAP Response      |
        |                      |   CANNOT_PROVIDE_EXTERNAL   |
        |                      |<----------------------------|
        |     (4) Error:       |                             |
        |ConflictInMappingEntry|                             |
        |<---------------------|                             |
        | (5) AddPortMapping   |                             |
        |   ExternalPort=5485  |                             |
        |--------------------->|                             |
        |                      |   (6) PCP MAP Request       |
        |                      |Suggested External Port=5485 |
        |                      |       PREFER_FAILURE        |
        |                      |---------------------------->|
        |                      |   (7) PCP MAP Response      |
        |                      |   CANNOT_PROVIDE_EXTERNAL   |
        |                      |<----------------------------|
        |     (8) Error:       |                             |
        |ConflictInMappingEntry|                             |
        |<---------------------|                             |
                               ....
        | (a) AddPortMapping   |                             |
        |   ExternalPort=6591  |                             |
        |--------------------->|                             |
        |                      |   (b) PCP MAP Request       |
        |                      |Suggested External Port=6591 |
        |                      |       PREFER_FAILURE        |
        |                      |---------------------------->|
        |                      |   (c) PCP MAP Response      |
        |                      |   CANNOT_PROVIDE_EXTERNAL   |
        |                      |<----------------------------|
        |     (d) Error:       |                             |
        |ConflictInMappingEntry|                             |
        |<---------------------|                             |


                 Figure 7: Flow Example (Negative Answer)

      Note: According to some experiments, some UPnP 1.0 Control Point
      implementations, e.g., uTorrent, simply try the same external port
      a number of times (usually 4 times) and then fail if the port is
      in use.  Also note that some applications use
      GetSpecificPortMappingEntry() to check whether a mapping exists.



Boucadair, et al.       Expires October 26, 2013               [Page 14]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


5.7.  Listing One or a Set of Mappings

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

   GetGenericPortMappingEntry() and GetListOfPortMappings() methods MUST
   NOT be proxied to the PCP Server since a local mapping is maintained
   by the IGD-PCP IWF.

   Upon receipt of GetSpecificPortMappingEntry() from a UPnP Control
   Point, the IGD-PCP IWF MUST check first if the external port number
   is used by the requesting UPnP Control Point.  If the external port
   is already in use by the requesting UPnP Control Point, the IGD-PCP
   IWF MUST send back a positive answer.  If not, the IGD-PCP IWF MUST
   relay to the PCP Server a MAP request, with short lifetime (e.g., 60
   seconds), including a PREFER_FAILURE Option.  If the IGD-PCP IWF
   fails to send the MAP request to its PCP Server, it follows the
   behavior defined in Section 5.1.  If the requested external port is
   in use, a PCP error message will be sent by the PCP Server to the
   IGD-PCP IWF indicating CANNOT_PROVIDE_EXTERNAL as the error cause.
   Then, the IGD-PCP IWF relays a negative message to the UPnP Control
   Point.  If the port is not in use, the mapping will be created by the
   PCP Server and a positive response will be sent back to the IGD-PCP
   IWF.  Once received by the IGD-PCP IWF, it MUST relay a negative
   message to the UPnP Control Point indicating NoSuchEntryInArray as
   the error code so that the UPnP control point knows the queried
   mapping doesn't exist.

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

   A UPnP Control Point requests the deletion of one or a list of
   mappings by issuing DeletePortMapping() or DeletePortMappingRange().

   In IGD:2, we assume the IGD applies the appropriate security policies
   to determine whether a Control Point has the rights to delete one or
   a set of mappings.  When authorization fails, the "606 Action Not
   Authorized" error code is returned to the requesting Control Point.

   When DeletePortMapping() or DeletePortMappingRange() is received by
   the IGD-PCP IWF, it first checks if the requested mappings to be
   removed are present in the local mapping table.  If no mapping
   matching the request is found in the local table, an error code is
   sent back to the UPnP Control Point: "714 NoSuchEntryInArray" for
   DeletePortMapping() or "730 PortMappingNotFound" for
   DeletePortMappingRange().




Boucadair, et al.       Expires October 26, 2013               [Page 15]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   Figure 8 shows an example of a UPnP Control Point asking to delete a
   mapping which is not instantiated in the local table of the IWF.

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


                   Figure 8: Local Delete (IGD-PCP IWF)

   If a mapping matches in the local table, a PCP MAP delete request is
   generated.  If no NAT is enabled in the IGD, the IGD-PCP IWF uses the
   input arguments as included in DeletePortMapping().  If a NAT is
   enabled in the IGD, the IGD-PCP IWF instead uses the corresponding IP
   address and port number as assigned by the local NAT.

   If the IGD-PCP IWF fails to send the MAP request to its PCP Server,
   it follows the behavior defined in Section 5.1.

   When a positive answer is received from the PCP Server, the IGD-PCP
   IWF updates its local mapping table (i.e., removes the corresponding
   entry) and notifies the UPnP Control Point about the result of the
   removal operation.  Once the PCP MAP delete request is received by
   the PCP Server, it removes the corresponding entry.  A PCP MAP
   SUCCESS response is sent back if the removal of the corresponding
   entry was successful; if not, a PCP Error is sent back to the IGD-PCP
   IWF including the corresponding error cause (see Section 4.3).

   If DeletePortMappingRange() is used, the IGD-PCP IWF does a lookup in
   its local mapping table to retrieve individual mappings instantiated
   by the requesting Control Point (i.e., authorization checks) and
   matching the signaled port range (i.e., the external port is within
   the "StartPort" and "EndPort" arguments of DeletePortMappingRange()).
   If no mapping is found, the "730 PortMappingNotFound" error code is
   sent to the UPnP Control Point (Figure 9).  If one or more mappings
   are found, the IGD-PCP IWF generates individual PCP MAP delete
   requests corresponding to these mappings (see the example shown in
   Figure 10).





Boucadair, et al.       Expires October 26, 2013               [Page 16]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   The IGD-PCP IWF MAY send a positive answer to the requesting UPnP
   Control Point without waiting to receive all the answers from the PCP
   Server.

                                 UPnP-PCP
   UPnP Control                Interworking
      Point                      Function                  PCP Server
        |                            |                           |
        |(1)DeletePortMappingRange() |                           |
        |     StartPort=8596         |                           |
        |     EndPort  =9000         |                           |
        |     Protocol =UDP          |                           |
        |--------------------------->|                           |
        |                            |                           |
        |       (2) Error:           |                           |
        |   PortMappingNotFound      |                           |
        |<---------------------------|                           |
        |                            |                           |


     Figure 9: Flow example when an error encountered when processing
                         DeletePortMappingRange()

   This example illustrates the exchanges that occur when the IWF
   receives DeletePortMappingRange().  In this example, only two
   mappings having the external port number in the 6000-6050 range are
   maintained in the local table.  The IWF issues two MAP requests to
   delete these mappings.























Boucadair, et al.       Expires October 26, 2013               [Page 17]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


                                 UPnP-PCP
   UPnP Control                Interworking
      Point                      Function                  PCP Server
        |                            |                           |
        |(1)DeletePortMappingRange() |                           |
        |     StartPort=6000         |                           |
        |     EndPort  =6050         |                           |
        |     Protocol =UDP          |                           |
        |--------------------------->|                           |
        |                            |                           |
        |                            |    (2a)PCP MAP Request    |
        |                            |       protocol=UDP        |
        |                            |   internal-ip-address     |
        |                            |      internal-port        |
        |                            |   external-ip-address     |
        |                            |   external-port= 6030     |
        |                            |   Requested-lifetime= 0   |
        |                            |-------------------------->|
        |                            |                           |
        |                            |    (2c)PCP MAP Request    |
        |                            |       protocol=UDP        |
        |                            |   internal-ip-address     |
        |                            |      internal-port        |
        |                            |   external-ip-address     |
        |                            |   external-port= 6045     |
        |                            |   Requested-lifetime= 0   |
        |                            |-------------------------->|
        |                            |                           |
        |    (2b)Positive answer     |                           |
        |<---------------------------|                           |
        |                            |                           |

              Figure 10: Example of DeletePortMappingRange()

5.9.  Renewing a Mapping

   Because of the incompatibility of mapping lifetimes between UPnP IGD
   and PCP, the IGD-PCP IWF MUST simulate long and even infinite
   lifetimes.  Indeed, for requests having a requested infinite
   PortMappingLeaseDuration, the IGD-PCP IWF MUST set the Requested
   Lifetime of the corresponding PCP request to 4294967296.  If
   PortMappingLeaseDuration is not infinite, the IGD-PCP IWF MUST set
   the Requested Lifetime of the corresponding PCP request to the same
   value as PortMappingLeaseDuration.  Furthermore, the IGD-PCP
   Interworking Function MUST maintain an additional timer set to the
   initial requested PortMappingLeaseDuration.  Upon receipt of a
   positive answer from the PCP server, the IGD-PCP IWF relays the
   corresponding UPnP IGD response to the requesting UPnP Control Point



Boucadair, et al.       Expires October 26, 2013               [Page 18]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   with PortMappingLeaseDuration set to the same value as the one of the
   initial request.  Then, the IGD-PCP IWF MUST periodically renew the
   constructed PCP mapping until the expiry of PortMappingLeaseDuration.
   Responses received when renewing the mapping MUST NOT be relayed to
   the UPnP Control Point.

   In case an error is encountered during mapping renewal, the IGD-PCP
   Interworking Function has no means to inform the UPnP Control Point.

5.10.  Rapid Recovery

   When the IWF is co-located with the DHCP server, the state maintained
   by the IWF MUST be updated using the state in the local DHCP server.
   Particularly, if an IP address expires or is released by an internal
   host, the IWF MUST delete all the mappings bound to that internal IP
   address.

   Upon change of the external IP address of the IWF, the IWF MAY renew
   the mappings it maintained.  This can be achieved only if a full
   state table is maintained by the IWF.  If the port quota is not
   exceeded in the PCP server, the IWF will receive a new external IP
   address and port numbers.  The IWF has no means to notify the change
   of the external IP address and port to internal UPnP Control Points.
   Stale mappings will be maintained by the PCP Server until their
   lifetime expires.

   [I-D.ietf-pcp-base] defines a procedure for the PCP Server to notify
   PCP Clients about changes related to the mappings it maintains.  When
   an unsolicited ANNOUNCE is received, the IWF makes one or more MAP
   requests with the PREFER_FAILURE option to re-install its mappings.
   If the PCP server cannot create the requested mappings (signaled with
   the CANNOT_PROVIDE_EXTERNAL error response), the IWF has no means to
   notify the change of the external IP address and port to internal
   UPnP Control Points.

   Unsolicited PCP MAP responses received from a PCP Server are handled
   as any normal MAP response.  If a response indicates that the
   external IP address or port has changed, the IWF has no means to
   notify the internal UPnP Control Point of this change.

   Further analysis of PCP failure scenarios for the IGD-PCP
   Interworking Function are discussed in [I-D.boucadair-pcp-failure].









Boucadair, et al.       Expires October 26, 2013               [Page 19]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


6.  IANA Considerations

   This document makes no request of IANA.

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

7.  Security Considerations

   The IGD:2 authorization framework SHOULD be used [IGD2].  When only
   IGD:1 is available, operation on the behalf of a third party SHOULD
   NOT be allowed.

   This document defines a procedure to create PCP mappings for third
   party devices belonging to the same subscriber.  Means to prevent a
   malicious user from creating mappings on behalf of a third party must
   be enabled as discussed in Section 13.1 of [I-D.ietf-pcp-base].

   The security considerations discussed in [I-D.ietf-pcp-base] and
   [Sec_DCP] should be taken into account.

8.  Acknowledgments

   Authors would like to thank F.  Fontaine, C.  Jacquenet, X.  Deng, G.
   Montenegro, D.  Thaler, R.  Tirumaleswar, P.  Selkirk, T.  Lemon, V.
   Gurbani, and P.  Yee for their review and comments.

   F.  Dupont contributed to previous versions of this document.  Thanks
   to him for his thorough reviews and contribution.

9.  References

9.1.  Normative References

   [I-D.ietf-pcp-base]
              Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
              Selkirk, "Port Control Protocol (PCP)", draft-ietf-pcp-
              base-29 (work in progress), November 2012.

   [IGD1]     UPnP Forum, , "WANIPConnection:1 Service (http://
              www.upnp.org/specs/gw/UPnP-gw-
              WANIPConnection-v1-Service.pdf)", November 2001.

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





Boucadair, et al.       Expires October 26, 2013               [Page 20]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   [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.boucadair-pcp-failure]
              Boucadair, M. and R. Penno, "Port Control Protocol (PCP)
              Failure Scenarios", draft-boucadair-pcp-failure-05 (work
              in progress), February 2013.

   [I-D.ietf-pcp-description-option]
              Boucadair, M., Penno, R., and D. Wing, "PCP Description
              Option", draft-ietf-pcp-description-option-00 (work in
              progress), March 2013.

   [I-D.ietf-pcp-dhcp]
              Boucadair, M., Penno, R., and D. Wing, "DHCP Options for
              the Port Control Protocol (PCP)", draft-ietf-pcp-dhcp-07
              (work in progress), March 2013.

   [I-D.ietf-pcp-proxy]
              Boucadair, M., Penno, R., and D. Wing, "Port Control
              Protocol (PCP) Proxy Function", draft-ietf-pcp-proxy-02
              (work in progress), February 2013.

   [RFC6146]  Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
              NAT64: Network Address and Protocol Translation from IPv6
              Clients to IPv4 Servers", RFC 6146, April 2011.

   [RFC6333]  Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
              Stack Lite Broadband Deployments Following IPv4
              Exhaustion", RFC 6333, August 2011.

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

Authors' Addresses

   Mohamed Boucadair
   France Telecom
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com








Boucadair, et al.       Expires October 26, 2013               [Page 21]

Internet-Draft              UPnP IGD-PCP IWF                  April 2013


   Reinaldo Penno
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, California  95134
   USA

   Email: repenno@cisco.com


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

   Email: dwing@cisco.com


































Boucadair, et al.       Expires October 26, 2013               [Page 22]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/