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Internet Engineering Task Force (IETF)                      M. BoucadairRequest for Comments: 7220                                France TelecomCategory: Standards Track                                       R. PennoISSN: 2070-1721                                                  D. Wing                                                                   Cisco                                                                May 2014Description Option for the Port Control Protocol (PCP)Abstract   This document extends the Port Control Protocol (PCP) with the   ability to associate a description with a PCP-instantiated mapping.   It does this by defining a new DESCRIPTION option.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7220.Copyright Notice   Copyright (c) 2014 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 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.Boucadair, et al.            Standards Track                    [Page 1]

RFC 7220                 PCP Description Option                 May 2014Table of Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .22.  Format  . . . . . . . . . . . . . . . . . . . . . . . . . . .33.  Behavior  . . . . . . . . . . . . . . . . . . . . . . . . . .44.  Security Considerations . . . . . . . . . . . . . . . . . . .55.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .56.  References  . . . . . . . . . . . . . . . . . . . . . . . . .56.1.  Normative References  . . . . . . . . . . . . . . . . . .56.2.  Informative References  . . . . . . . . . . . . . . . . .61.  Introduction   This document extends the base PCP [RFC6887] with the ability to   associate a human-readable description with a PCP-instantiated   mapping.  It does this by defining a new DESCRIPTION option.   This PCP option can be used in simple scenarios with a PCP client and   PCP server, as well as in more complex scenarios where an   interworking function is used to proxy between a UPnP IGD Control   Point and a PCP server [RFC6970].   Querying the PCP server to get the description text of an existing   mapping is out of scope.   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 inRFC 2119 [RFC2119].Boucadair, et al.            Standards Track                    [Page 2]

RFC 7220                 PCP Description Option                 May 20142.  Format   The format of the DESCRIPTION option is shown in Figure 1.       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=128|  Reserved     |           Length              |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                           Description                         |      :                                                               :      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+        This Option:         Option Name: DESCRIPTION         Number: 128         Purpose: Used to associate a text description with a mapping         Valid for Opcodes: MAP, PEER         Length: Variable,  maximum 1016 octets.         May appear in: request. May appear in response only if it                        appeared in the associated request.         Maximum occurrences: 1                       Figure 1: DESCRIPTION Option   The 'Reserved' field is initialized as specified inSection 7.3 of   [RFC6887].   The Description field MUST carry UTF-8 encoded [RFC3629] description   text.  The description text MUST NOT be null terminated.  The length   of the description text is indicated by the Length field.  In   particular, the description text is not null terminated, and when a   client or server receives a DESCRIPTION option, it MUST NOT rely on   the presence of a NUL character in the wire format data to identify   the end of the text.   This option can be used by a user (or an application) to indicate a   description associated with a given mapping, such as "FTP server",   "My remote access to my CP router", "Camera", "Network attached   storage serve", etc.Boucadair, et al.            Standards Track                    [Page 3]

RFC 7220                 PCP Description Option                 May 2014   How the content of the DESCRIPTION option is used is deployment-   specific.  For example, the description text can be used by the   entity managing the PCP server for many purposes, such as the   following:   o  The description text can be used as a hint when cleaning a mapping      table by an administrator.   o  In some deployments making use of a portal to instruct PCP      mappings (e.g., Section 5.2 of [PCP-DEPLOY]), the description text      can be used to store a subscriber identifier.3.  Behavior   Support for the DESCRIPTION option by PCP servers and PCP clients is   optional.  This option (Code 128; see Figure 1) MAY be included in a   PCP MAP/PEER request to associate a description with the requested   mapping.   A PCP server MAY ignore the DESCRIPTION option sent to it by a PCP   client (e.g., if it does not support the option or if it is   configured to ignore it).  To signal that it has not accepted the   option, a PCP server simply does not include the DESCRIPTION option   in the response.  If the PCP client does not receive a DESCRIPTION   option in a response to a request enclosing a DESCRIPTION option,   this means the PCP server does not support the option or it is   configured to ignore it.   If the DESCRIPTION option is not included in the PCP client request,   the PCP server MUST NOT include the DESCRIPTION option in the   associated response.   A PCP server SHOULD be able to store at least 128 bytes for a   description.  When the PCP server receives a DESCRIPTION option, it   first stores the value of the received Description field, truncating   it if it cannot store the entire value.  The server MUST then send   the stored value back to the PCP client in the DESCRIPTION option in   the response.   If the PCP client request contains invalid DESCRIPTION options (e.g.,   the content is not a legal UTF-8 string), the PCP server MUST ignore   the request (i.e., MUST NOT return a DESCRIPTION option in the   response).   To update the description text of a mapping maintained by a PCP   server, the PCP client generates a PCP MAP/PEER renewal request that   includes a DESCRIPTION option carrying the new description text.   Upon receipt of the PCP request, the PCP server proceeds to the sameBoucadair, et al.            Standards Track                    [Page 4]

RFC 7220                 PCP Description Option                 May 2014   operations to validate a MAP/PEER request refreshing an existing   mapping.  If validation checks are successfully passed, the PCP   server replaces the old description text with the new one included in   the DESCRIPTION option, and the PCP server returns the updated   description text in the response, truncated (if necessary) as   described above.   The PCP client uses an empty DESCRIPTION option (i.e., Length set to   0) to erase the description text associated with a mapping.  To   indicate that the PCP server has successfully cleared the description   text associated with a mapping, the PCP server returns the empty   DESCRIPTION option in the response.4.  Security Considerations   PCP-related security considerations are discussed in [RFC6887].  In   addition, administrators of PCP servers SHOULD configure a maximum   description length that does not lead to exhausting storage resources   in the PCP server.   If the PCP client and the PCP server are not under the same   administrative entity, the DESCRIPTION option has the potential to   leak privacy-related information.  PCP clients should not use the   DESCRIPTION option for such leakage.  For example, the option should   not be used to include user identifiers, locations, or names.  Refer   toSection 3.2 of [RFC6462] for a discussion on information leakage.5.  IANA Considerations   IANA has allocated the following value in the "PCP Options" registry   (http://www.iana.org/assignments/pcp-parameters) from the optional-   to-process range (seeSection 19.4 of [RFC6887]):      DESCRIPTION set to 128 (seeSection 2)6.  References6.1.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO              10646", STD 63,RFC 3629, November 2003.   [RFC6887]  Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and              P. Selkirk, "Port Control Protocol (PCP)",RFC 6887, April              2013.Boucadair, et al.            Standards Track                    [Page 5]

RFC 7220                 PCP Description Option                 May 20146.2.  Informative References   [PCP-DEPLOY]              Boucadair, M., "Port Control Protocol (PCP) Deployment              Models", Work in Progress, April 2014.   [RFC6462]  Cooper, A., "Report from the Internet Privacy Workshop",RFC 6462, January 2012.   [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.Authors' Addresses   Mohamed Boucadair   France Telecom   Rennes  35000   France   EMail: mohamed.boucadair@orange.com   Reinaldo Penno   Cisco   USA   EMail: repenno@cisco.com   Dan Wing   Cisco Systems, Inc.   170 West Tasman Drive   San Jose, California  95134   USA   EMail: dwing@cisco.comBoucadair, et al.            Standards Track                    [Page 6]