ECRIT                                                     H. Schulzrinne
Internet-Draft                                       Columbia University
Intended status: Informational                                  L. Liess
Expires: December 19, 2008 April 15, 2009                                 Deutsche Telekom
                                                           H. Tschofenig
                                                  Nokia Siemens Networks
                                                                B. Stark
                                                                    AT&T
                                                                A. Kuett
                                                                   Skype
                                                           June 17,
                                                        October 12, 2008

          Location Hiding: Problem Statement and Requirements
              draft-ietf-ecrit-location-hiding-req-00.txt
              draft-ietf-ecrit-location-hiding-req-01.txt

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Abstract

   The emergency services architecture developed in the IETF Emergency
   Context Resolution with Internet Technology (ECRIT) working group
   describes an architecture where location information is provided by
   access networks to end points or VoIP service providers in order to
   determine the correct dial string and information to route the call
   to a Public Safety Answering Point (PSAP).  For determining the PSAP
   Uniform Resource Identifier (URI) the usage of the Location-to-Service Location-to-
   Service Translation (LoST) Protocol is envisioned.

   This document explores the architectural impact for the IETF
   emergency services architecture for situations where the Internet
   Access Provider (IAP) and/or the Internet Service Provider (ISP) are
   only willing to disclose limited or no location information.

   This document provides a problem statement and lists requirements.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Emergency Services Architecture  . . . . . . . . . . . . .  3
     1.2.  Location Hiding  . . . . . . . . . . . . . . . . . . . . .  3
     1.3.  Location by Reference  . . . . . . . . . . . . . . . . . .  3  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  4
     3.1.  High-Level Requirements  . . . . . . . . . . . . . . . . .  4
     3.2.  Detailed Requirements  . . . . . . . . . . . . . . . . . .  5
     3.3.  Desirable Properties . . . . . . . . . . . . . . . . . . .  6
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  6
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  6
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .  6  7
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     7.1.  Normative References . . . . . . . . . . . . . . . . . . .  7
     7.2.  Informative References . . . . . . . . . . . . . . . . . .  7
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  8
   Intellectual Property and Copyright Statements . . . . . . . . . . 10

1.  Introduction

1.1.  Emergency Services Architecture

   The emergency services architecture developed in the IETF Emergency
   Context Resolution with Internet Technology (ECRIT) working group,
   see [I-D.ietf-ecrit-framework], describes an architecture where
   location information is provided by access networks to end points or
   VoIP service providers in order to determine the correct dial string
   and information to route the call to a Public Safety Answering Point
   (PSAP).  The Location-to-
   Service Location-to-Service Translation (LoST) Protocol [I-D.ietf-ecrit-lost]
   [RFC5222] allows callers and other call-routing entities to determine
   the PSAP Uniform Resource Identifier (URI) for a specific
   geographical location together with a service URI
   [I-D.ietf-ecrit-service-urn]. [RFC5031].  The
   basic architecture is shown in Figure 1 of [I-D.ietf-ecrit-framework]
   and further detailed in the message flow in Figure 2 of
   [I-D.ietf-ecrit-framework].

   For emergency services, location information is needed for two
   different purposes, namely for routing an emergency in three ways:
   1.  Emergency call routing to the PSAP that is responsible for a
       specific geographical region (and also for
   requested service, such as police or ambulance) and for dispatch
   2.  Dispatch of the emergency personell personnel to the scene of an accident,
       crime or other types of incidents. incidents
   3.  Additionally, a VSP may need to verify that an call is indeed an
       emergency call and may therefore require location information to
       ensure that calls routed to a specific URI point to a PSAP.

   It is very important to note that this document only discusses
   location hiding in the context of location information that is need
   for call routing.  ISPs have no interest or even legal basis for
   hiding location information from emergency services personnel.

1.2.  Location Hiding

   In some cases, location providers (e.g., Internet Access Providers
   (IAPs) and/or the Internet Service Providers (ISPs) (ISPs)) are afraid unwilling to
   provide precise location information to end points or VSPs, as is
   called for in the above model.  The decision to deny location can be
   driven by a number of technical and business concerns.  Some
   providers may perceive a risk that allowing users to access location
   information for non-emergency purposes or prior to an emergency call
   will incur additional server load and thus costs.
   Hence, they do not to disclose precise location information (at the
   quality suitable for dispatch emergency personell by the PSAP
   operator) or not to disclose any location information.

   In some other cases IAPs and ISPs  Other providers
   may not want to make location information available without the
   ability to charge for it.  This is
   a pure business decision.

1.3.  Location by Reference

   The work on the Location Configuration Protocol (LCP) indicated the
   need to provide the capability to obtain Location-by-References
   (LbyRs) in addition to Location-by-Value (LbyV) from a Location
   Information Server (LIS).

   The LCP problem statement and requirements document can be found in
   [I-D.ietf-geopriv-l7-lcp-ps].  The requirements for obtaining an LbyR
   via the LCP and the corresponding dereferencing step can be found in
   [I-D.ietf-geopriv-lbyr-requirements].

   HTTP Enabled Location Delivery (HELD), see
   [I-D.ietf-geopriv-http-location-delivery], is an instantiation of the
   LCP concept and allows LbyVs and LbyRs to be requested.

   A location reference may already satisfy the requirement for location
   hiding if the PSAP has the appropriate credentials to resolve the
   reference.  This requires a trust relationship between the PSAP and
   the ISP.  Note that the requirement being met here is for delivery of
   location information to the PSAP, not for LoST routing or for
   validation at the VSP.

   Unfortunately, a location reference is not compatible with LoST, as
   LoST requires an information value rather than a reference.  Also,
   LoST servers may be operated by the VSP, which may not have a trust
   relationship with the ISP.

   This document explores the architectural impact for the current
   architecture and lists requirements.

2.  Terminology

   The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119], with the
   important qualification that, unless otherwise stated, these terms
   apply to the design of an solution supporting location hiding, not
   its implementation or application.

   This document reuses terminology from [I-D.ietf-geopriv-l7-lcp-ps].

3.  Requirements

   This section presents requirements.

3.1.  High-Level Requirements
   Req-A:  There SHOULD MUST be a way an access network can withhold detailed
      location information from any entity it wishes to, and
      specifically, the endpoint, and a VSP.

   Req-B:  The ISP/IAP MUST support the ability of the endpoint or the
      VSP to route emergency calls.

   Req-C:  The VSP MUST be able to validate that a call purported to be
      an emergency call is being routed to a bona fide URI, which is
      denoted by being a URI in LoST for the designated emergency
      service.

   Req-D:  Precise  The PSAP MUST be provided precise location information must be conveyed (either LbyR (by
      value) for emergency callers.  The endpoint and/or VSP may provide
      this information either by value or
      LbyV) to the PSAP. by reference.

3.2.  Detailed Requirements

   Req-1:  A  The proposed solution MUST NOT assume a business or trust
      relationship between an ISP and a the caller's VSP
      MUST NOT be assumed. and the caller's ISP.

   Req-2:  A solution MUST consider deployment scenarios where a VSP is
      outside the jurisdiction of the PSAP.

   Req-3:  The solution MUST offer automated discovery of servers and
      other behavior, i.e., no manual configuration can be assumed.

   Req-4:  The steps needed by the endpoint for emergency calling SHOULD
      be no different when location is withheld vs. when location is not
      withheld.  In particular, user agents cannot require additional
      configuration to discover which particular environment (hiding or
      no hiding) they find themselves in.

   Req-5:  The solution SHOULD work for non-SIP entities, without the
      ISP/IAP having to support these protocols.

   Req-6:  The solution MUST work if PSAP boundaries have holes.

   Req-7:  The solution MUST NOT assume the existence of Emergency
      Service Routing Proxies (ESRPs) per country, state and city.

   Req-8:  The solution MUST consider that service boundaries for
      different emergency services may differ, but they overlap at the
      location of the caller.

   Req-9:  UAs MUST NOT have to deduce  Though the desired behavior by trial-
      and-error operations, such as LbyR resolutions, fail, as failures solution MAY add latency during steps to the emergency call setup.  The solution
      routing process described in [framework], these steps MUST NOT
      significantly increase call setup latency.  For example, the
      revised process MUST NOT include "trial-and-error" operations on
      its critical path, such as attempts at LbyR resolutions that may
      take time to time out.

   Req-10:  The solution MUST allow the end host to determine PSAP/ESRP
      URLs prior to the call, for all emergency services.

   Req-11:  The solution MUST allow UAs to discover at least their dial
      string ahead of the emergency call.

   Req-12:  The solution MUST have minimal impact on UAs.

   Req-13:  The solution MUST NOT interfere with the use of LoST for
      non-emergency services.

   Req-14:  Deleted

   Req-15:  Calls may reach a PSTN gateway, rather than the PSAP
      directly.

3.3.  Desirable Properties

   o  The solution MUST NOT shift effort(externality), i.e., the
      convenience of the location-hiding ISP MUST NOT impose a burden on
      user agents or non-hiding ISPs/IAPs and SHOULD NOT impose a burden
      on VSPs.

   o  The solution SHOULD minimize the impact on LoST, SIP conveyance
      [I-D.ietf-sip-location-conveyance] and DHCP.

   o  The solution SHOULD NOT rely on DHCP for LoST configuration, as
      the information in the DHCP server provided by the ISP may not
      reach the UA, due to NATs.

4.  IANA Considerations

   This document does not require actions by IANA.

5.  Security Considerations

   This document does not raise additional security consideration beyond
   those mentioned in [I-D.ietf-geopriv-l7-lcp-ps] and discussed in this
   document.

6.  Acknowledgments

   We would like to thank the following ECRIT working group members (in
   no particular order) for their contributions:

   o  Andrew Newton (andy@hxr.us)
   o  James Winterbottom (James.Winterbottom@andrew.com)
   o  Brian Rosen (br@brianrosen.net)
   o  Richard Barnes (rbarnes@bbn.com)
   o  Marc Linsner (mlinsner@cisco.com)
   o  Ted Hardie (hardie@qualcomm.com)

7.  References

7.1.  Normative References

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

7.2.  Informative References

   [I-D.ietf-geopriv-l7-lcp-ps]
              Tschofenig, H. and H. Schulzrinne, "GEOPRIV Layer 7
              Location Configuration Protocol; Problem Statement and
              Requirements", draft-ietf-geopriv-l7-lcp-ps-07 draft-ietf-geopriv-l7-lcp-ps-08 (work in
              progress), March June 2008.

   [I-D.ietf-sip-location-conveyance]
              Polk, J. and B. Rosen, "Location Conveyance for the
              Session Initiation Protocol",
              draft-ietf-sip-location-conveyance-10 (work in progress),
              February
              September 2008.

   [I-D.ietf-ecrit-framework]
              Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,
              "Framework for Emergency Calling using Internet
              Multimedia", draft-ietf-ecrit-framework-05 draft-ietf-ecrit-framework-06 (work in
              progress), February July 2008.

   [I-D.ietf-ecrit-lost]

   [RFC5222]  Hardie, T., Newton, A., Schulzrinne, H., and H.
              Tschofenig, "LoST: A Location-to-Service Translation
              Protocol", draft-ietf-ecrit-lost-10 (work in progress),
              May RFC 5222, August 2008.

   [I-D.ietf-geopriv-lbyr-requirements]
              Marshall, R., "Requirements for a Location-by-Reference
              Mechanism", draft-ietf-geopriv-lbyr-requirements-02 draft-ietf-geopriv-lbyr-requirements-03 (work
              in progress), February July 2008.

   [I-D.ietf-ecrit-service-urn]

   [RFC5031]  Schulzrinne, H., "A Uniform Resource Name (URN) for
              Emergency and Other Well-Known Services",
              draft-ietf-ecrit-service-urn-07 (work in progress),
              August 2007. RFC 5031,
              January 2008.

   [I-D.ietf-geopriv-http-location-delivery]
              Barnes, M., Winterbottom, J., Thomson, M., and B. Stark,
              "HTTP Enabled Location Delivery (HELD)",
              draft-ietf-geopriv-http-location-delivery-07
              draft-ietf-geopriv-http-location-delivery-09 (work in
              progress), April September 2008.

Authors' Addresses

   Henning Schulzrinne
   Columbia University
   Department of Computer Science
   450 Computer Science Building
   New York, NY  10027
   US

   Phone: +1 212 939 7004
   Email: hgs+ecrit@cs.columbia.edu
   URI:   http://www.cs.columbia.edu

   Laura Liess
   Deutsche Telekom Networks
   Deutsche Telekom Allee 7
   Darmstadt, Hessen  64295
   Germany

   Phone:
   Email: Laura.Liess@t-systems.com
   URI:   http://www.telekom.de
   Hannes Tschofenig
   Nokia Siemens Networks
   Linnoitustie 6
   Espoo  02600
   Finland

   Phone: +358 (50) 4871445
   Email: Hannes.Tschofenig@gmx.net
   URI:   http://www.tschofenig.priv.at

   Barbara Stark
   AT&T
   725 W Peachtree St, NE
   Atlanta, GA  30308
   USA

   Phone: +1 404 499 7026
   Email: barbara.stark@att.com

   Andres Kuett
   Skype

   Email: andres.kytt@skype.net

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