Internet DRAFT - draft-ripke-pcp-tunnel-id-option

draft-ripke-pcp-tunnel-id-option







Internet Engineering Task Force                                 A. Ripke
Internet-Draft                                                  T. Dietz
Intended status: Informational                                J. Quittek
Expires: April 30, 2015                                              NEC
                                                             R. da Silva
                                                          Telefonica I+D
                                                        October 27, 2014


                       PCP Third Party ID Option
                  draft-ripke-pcp-tunnel-id-option-02

Abstract

   This document describes a new Port Control Protocol (PCP) option
   called THIRD_PARTY_ID.  It serves for identifying a Third Party in
   addition to the means that PCP's THIRD_PARTY option already provides
   for that purpose.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 30, 2015.

Copyright Notice

   Copyright (c) 2014 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
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   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of



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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Target Scenarios  . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Carrier-hosted UPnP IGD-PCP IWF . . . . . . . . . . . . .   5
     3.2.  Carrier Web Portal  . . . . . . . . . . . . . . . . . . .   6
     3.3.  Other Use Cases . . . . . . . . . . . . . . . . . . . . .   6
   4.  Format  . . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  Behavior  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Generating a Request  . . . . . . . . . . . . . . . . . .   8
     5.2.  Processing a Request  . . . . . . . . . . . . . . . . . .   8
     5.3.  Processing a Response . . . . . . . . . . . . . . . . . .   8
   6.  Alternative . . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   The IETF has specified the Port Control Protocol (PCP) ([RFC6887]) to
   control how packets are translated and forwarded by a PCP-controlled
   device such as a network address translator (NAT) or firewall.

   This draft focuses on the application of PCP's THIRD_PARTY option
   that is used when the PCP client sends requests that concern other
   internal hosts than the host of the PCP client.  This is, for
   example, the case if port mapping requests for a carrier grade NAT
   (CGN) are not sent from PCP clients at the subscribers, but from a
   PCP Interworking Function which requests port mappings.

   The issue addressed by the THIRD_PARTY_ID option is that there are
   CGN deployments that do not distinguish internal hosts by their IP
   address only, but use further identifiers for unique subscriber
   identification.  This is, for example, the case if a CGN supports
   overlapping private IP address spaces according to [RFC1918] for
   internal hosts of different subscribers.  Then different internal
   hosts are identified and mapped at the CGN by their IP address and an
   additional ID, for example, the ID of a tunnel between the CGN and
   the subscriber.  In such cases, the IP address contained in the
   THIRD_PARTY option is not sufficient.  An additional identifier needs




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   to be carried by the PCP protocol in order to uniquely identify the
   internal host.  The THIRD_PARTY_ID option serves this purpose.

   The THIRD_PARTY_ID option is defined for use in combination with the
   THIRD_PARTY option for the PCP opcodes MAP and PEER.

   We renamed the option name from TUNNEL_ID to THIRD_PARTY_ID to
   reflect the fact that this identifier is an extended THIRD_PARTY
   option for general applicability.

2.  Terminology

   The terminology defined in the specification of PCP [RFC6887]
   applies.

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

3.  Target Scenarios

   This section describes two scenarios that illustrate the use of the
   THIRD_PARTY_ID option:

   1.  a UPnP IGD-PCP IWF (Universal Plug and Play Internet Gateway
       Device - Port Control Protocol Interworking Function),

   2.  a carrier web portal for port mapping.

   Both scenarios are variants of the same basic scenario shown in
   Figure 1.  It has a carrier operating a CGN and a Port Control
   Protocol Interworking Function (PCP IWF) for subscribers to request
   port mappings at the CGN.  The PCP IWF communicates with the CGN
   using PCP.  For this purpose the PCP IWF contains a PCP client and
   the CGN is co-located with a PCP server.  The way subscribers
   interact with the PCP IWF for requesting port mapping for their
   internal hosts is not specified in this basic scenario, but more
   elaborated in the specific scenarios below.












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                       +------------------+
                       | Carrier          |    ==== IP packet tunnel(s)
   +--------------+    | +--------------+ |         between subscriber
   | Subscriber   +......+ Port Control | |         and CGN
   |              |    | | Interworking | |    #### PCP communication
   |              |    | | Function     | |    .... Subscriber - IWF
   |              |    | +-----#--------+ |         interaction
   |              |    |       #          |         (unspecified)
   |              |    | +-----#--------+ |
   | +----------+ |    | | PCP Server   | |
   | | Internal | |    | |              | |
   | | Host     +-+======+ CGN          +--------- Public Internet
   | +----------+ |    | +--------------+ |
   +--------------+    +------------------+

        Figure 1: Carrier hosted PCP IWF for port mapping requests

   Internal hosts in the subscriber's network use private IP addresses
   as specified in [RFC1918].  Since there is no NAT between the
   internal host and the CGN, there is an overlap of addresses used by
   internal hosts at different subscribers.  That is why the CGN needs
   more than just the internal host's IP address to distinguish internal
   hosts at different subscribers.  A commonly deployed method for
   solving this issue is using an additional identifier for this
   purpose.  A very good candidate for this additional identifier at the
   CGN is the ID of the tunnel that connects the CGN to the subscriber's
   network.

   Requests for port mappings from the PCP IWF to the CGN need to
   uniquely identify the internal host for which a port mapping is to be
   established or modified.  Already existing for this purpose is the
   THIRD_PARTY option that can be used to specify the internal host's IP
   address.  The THIRD_PARTY_ID option is introduced for carrying the
   additional (tunnel) information needed to identify the internal host
   in this scenario.

   The additional identifier for internal hosts needs to be included in
   MAP requests from the PCP IWF in order to uniquely identify the
   internal host that should have its address mapped.  This is the
   purpose that the new THIRD_PARTY_ID serves in this scenario.  It
   carries the additional identifier, that is the tunnel ID, that serves
   for identifying an internal host in combination with the internal
   host's (private) IP address.  The IP address of the internal host is
   included in the PCP IWF's mapping requests by using the THIRD_PARTY
   option.

   The information carried by the THIRD_PARTY_ID is not just needed to
   identify an internal host in a PCP request.  The CGN needs this



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   information in its internal mapping tables for translating packet
   addresses and for forwarding packets to subscriber-specific tunnels.

   How the carrier PCP IWF is managing port mappings, such as, for
   example, automatically extending the lifetime of a mapping, is beyond
   the scope of this document.

3.1.  Carrier-hosted UPnP IGD-PCP IWF

   This scenario further elaborates the basic one above by choosing UPnP
   as communication protocol between subscriber and the carrier's PCP
   IWF.  Then obviously, the PCP IWF is realized as an UPnP IGD-PCP IWF
   as specified in [RFC6970].

   As shown in Figure 2 it is assumed here that the UPnP IGD-PCP IWF is
   not embedded in the subscriber premises router, but offered as a
   service to the subscriber.  Further, it is assumed that the UPnP IGD-
   PCP IWF is not providing NAT functionality.

   This requires that the subscriber has a UPnP connection to the UPnP
   IGD-PCP IWF, which can, for example, be provided via (one of the)
   tunnel(s) connecting the subscriber's network to the CGN.  This
   connection can then be used by hosts in the subscriber's network to
   request port mappings at the CGN using UPnP as specified in
   [RFC6970].

                       +----------------+
                       | Carrier        |    ==== IP packet tunnel(s)
                       | +------------+ |         between subscriber
   +--------------+    | | UPnP       | |         and CGN
   | Subscriber   +......+ IGD-PCP    | |    #### PCP communication
   |              |    | | IWF        | |    .... Subscriber - UPnP
   |              |    | +-----#------+ |         IGD-PCP IWF
   |              |    |       #        |         interaction (UPnP)
   |              |    | +-----#------+ |
   | +----------+ |    | | PCP Server | |
   | | Internal | |    | |            | |
   | | Host     +-+======+ CGN        +--------- Public Internet
   | +----------+ |    | +------------+ |
   +--------------+    +----------------+

                        Figure 2: UPnP IGD-PCP IWF

   A potential extension to [RFC6970] regarding an additional state
   variable for the THIRD_PARTY_ID and regarding an additional error
   code for a mismatched THIRD_PARTY_ID and its processing might be a
   logical next step.  However, this is not in the scope of this
   document.



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3.2.  Carrier Web Portal

   This scenario shown in Figure 3 is different from the previous one
   concerning the protocol used between the subscriber and the IWF.
   Here HTTP(S) is the protocol that the subscriber uses for port
   mapping requests.  The subscriber may make requests manually using a
   web browser or automatically - as in the previous scenario - with
   hosts in the subscriber's network issuing port mapping requests on
   demand.

                       +----------------+
                       | Carrier        |    ==== IP packet tunnel(s)
                       | +------------+ |         between subscriber
   +--------------+    | | Web Portal | |         and CGN
   | Subscriber   +......+            | |    #### PCP communication
   |              |    | | PCP Client | |    .... Subscriber - portal
   |              |    | +-----#------+ |         interaction (HTTPS)
   |              |    |       #        |
   |              |    | +-----#------+ |
   | +----------+ |    | | PCP Server | |
   | | Internal | |    | |            | |
   | | Host     +-+======+ CGN        +--------- Public Internet
   | +----------+ |    | +------------+ |
   +--------------+    +----------------+

                       Figure 3: Carrier Web Portal

   The PCP IWF is realized as a combination of a web server and a PCP
   Client.  This scenario is also described as HTTP-triggered PCP client
   model in section 5.2 of [I-D.boucadair-pcp-deployment-cases].

3.3.  Other Use Cases

   Despite the fact that above scenarios solely use tunnel IDs the
   THIRD_PARTY_ID can include any layer 2 identifier like a MAC address
   or other subscriber identifiers as mentioned in section 6 of
   [I-D.boucadair-pcp-sfc-classifier-control].

4.  Format

   The THIRD_PARTY_ID option is formatted as shown in Figure 4.










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    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Option Code   |  Reserved     |   Option Length=16            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   |                 THIRD_PARTY_ID (128 bits)                     |
   |                                                               |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                      Figure 4: THIRD_PARTY_ID Option

   o  Option Name: THIRD_PARTY_ID

   o  Number: TBD

   o  Purpose: Identifies a request of an external IP address and port.

   o  Valid for opcodes: MAP, PEER, and all other for which the
      THIRD_PARTY option is valid for.

   o  Length: 16 octets

   o  May appear in: Request.  Must appear in response if it appeared in
      the associated request.

   o  Maximum occurrences: 1

   The fields are as follows:

   o  THIRD_PARTY_ID: A vendor specific identifier that can be used to
      identify a subscriber's CGN session and the port ranges to apply
      this request to.

   o  The THIRD_PARTY_ID is not bound to a specific identifier.  The
      size of 128 bits should be large enough for general applicability.

   The identifier field can contain any vendor specific value.  The
   option number is in the mandatory-to-process range (0-127), meaning
   that a request with a THIRD_PARTY_ID option is executed by the PCP
   server if and only if the THIRD_PARTY_ID option is supported by the
   PCP server.








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5.  Behavior

   The following sections describe the operations of a PCP client and a
   PCP server when generating the request and processing the request and
   response.

5.1.  Generating a Request

   In addition to generating a PCP request that is described in
   [RFC6887] the following has to be applied.  The THIRD_PARTY_ID option
   can be used together either with a PCP MAP or PEER opcode.  It MUST
   be used in combination with the THIRD_PARTY option which provides an
   IP address and port entered by the subscriber.  The THIRD_PARTY_ID
   option holds an identifier to allow the CGN to uniquely identify the
   internal host (specified in the THIRD_PARTY option) for which the
   port mapping is to be established or modified.  If the identifier is
   shorter than 128 bits then the THIRD_PARTY_ID option field is to be
   filled up with leading zeros up to 128 bits.

5.2.  Processing a Request

   The THIRD_PARTY_ID option is in the mandatory-to-process range and if
   the PCP server does not support this option it MUST return an
   UNSUPP_OPTION response.  If the provided THIRD_PARTY_ID is unknown/
   unavailable the PCP server MUST return a THIRD_PARTY_ID_UNKNOWN
   response.

5.3.  Processing a Response

   If the PCP client receives a THIRD_PARTY_ID_UNKNOWN response back for
   its previous request it SHOULD report an error message.  To where to
   report an error message is implementation dependent.

6.  Alternative

   An alternative to identify a tunnel affiliation in the given scenario
   could be using the DESCRIPTION ([RFC7220]) option to carry a tunnel
   ID option.  The DESCRIPTION option is to allow a text description to
   be attached to a port mapping.  But using the DESCRIPTION option for
   a tunnel ID might not be appropriate because it specifies using UTF-8
   and another requirement is that the description text must not be null
   terminated, which cannot always be met.

7.  IANA Considerations

   The following PCP Option Code is to be allocated in the mandatory-to-
   process range:




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   THIRD_PARTY_ID

   [NOTE for IANA: Please allocate a PCP Option Code at
   http://www.iana.org/assignments/pcp-parameters/pcp-
   parameters.xml#option-rules]

   The following PCP Result Code is to be allocated:

   THIRD_PARTY_ID_UNKNOWN

   [NOTE for IANA: Please allocate a PCP Result Code at
   http://www.iana.org/assignments/pcp-parameters/pcp-
   parameters.xml#result-codes]

8.  Security Considerations

   As this option is related to the use of the THIRD_PARTY option the
   corresponding security considerations apply.  Especially, the network
   on which the PCP messages are sent must be fully trusted.

9.  References

9.1.  Normative References

   [RFC1918]  Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
              E. Lear, "Address Allocation for Private Internets", BCP
              5, RFC 1918, February 1996.

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

   [RFC6887]  Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
              Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
              2013.

9.2.  Informative References

   [I-D.boucadair-pcp-deployment-cases]
              Boucadair, M., "Port Control Protocol (PCP) Deployment
              Models", draft-boucadair-pcp-deployment-cases-03 (work in
              progress), July 2014.

   [I-D.boucadair-pcp-sfc-classifier-control]
              Boucadair, M., "PCP as a Traffic Classifier Control
              Protocol", draft-boucadair-pcp-sfc-classifier-control-01
              (work in progress), October 2014.





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   [RFC6970]  Boucadair, M., Penno, R., and D. Wing, "Universal Plug and
              Play (UPnP) Internet Gateway Device - Port Control
              Protocol Interworking Function (IGD-PCP IWF)", RFC 6970,
              July 2013.

   [RFC7220]  Boucadair, M., Penno, R., and D. Wing, "Description Option
              for the Port Control Protocol (PCP)", RFC 7220, May 2014.

Authors' Addresses

   Andreas Ripke
   NEC
   Heidelberg
   Germany

   Email: ripke@neclab.eu


   Thomas Dietz
   NEC
   Heidelberg
   Germany

   Email: dietz@neclab.eu


   Juergen Quittek
   NEC
   Heidelberg
   Germany

   Email: quittek@neclab.eu


   Rafael Lopez da Silva
   Telefonica I+D
   Madrid
   Spain

   Email: ralds@tid.es











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