GENWiki

Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


rfc:rfc6444

Internet Engineering Task Force (IETF) H. Schulzrinne Request for Comments: 6444 Columbia University Category: Informational L. Liess ISSN: 2070-1721 Deutsche Telekom

                                                         H. Tschofenig
                                                Nokia Siemens Networks
                                                              B. Stark
                                                                  AT&T
                                                              A. Kuett
                                                                 Skype
                                                          January 2012
        Location Hiding: Problem Statement and Requirements

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 endpoints or Voice over IP (VoIP) service
 providers in order to determine the correct dial string and
 information to route the call to a Public Safety Answering Point
 (PSAP).  To determine the PSAP Uniform Resource Identifier (URI), the
 usage of the Location-to-Service Translation (LoST) protocol is
 envisioned.
 This document provides a problem statement and lists requirements 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.

Status of This Memo

 This document is not an Internet Standards Track specification; it is
 published for informational purposes.
 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).  Not all documents
 approved by the IESG are a candidate for any level of Internet
 Standard; see Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6444.

Schulzrinne, et al. Informational [Page 1] RFC 6444 Location Hiding Requirements January 2012

Copyright Notice

 Copyright (c) 2012 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Table of Contents

 1. Introduction ....................................................3
    1.1. Emergency Services Architecture ............................3
    1.2. Location Hiding ............................................3
    1.3. Location by Reference ......................................4
 2. Terminology .....................................................5
 3. Requirements ....................................................5
 4. Security Considerations .........................................7
 5. Acknowledgments .................................................7
 6. Normative References ............................................7

Schulzrinne, et al. Informational [Page 2] RFC 6444 Location Hiding Requirements January 2012

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 [RFC6443], describes an architecture where location information
 is provided by access networks to endpoints 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 Translation (LoST) protocol [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 URN [RFC5031].  The basic architecture is
 shown in Figure 1 of [RFC6443] and further detailed in the message
 flow in Figure 2 of [RFC6443].
 For emergency services, location information is needed for three
 purposes:
 1.  Emergency call routing to the PSAP that is responsible for a
     specific geographical region.
 2.  Dispatch of the emergency personnel to the scene of an accident,
     crime, or other type of incident.
 3.  Additionally, a Voice Service Provider (VSP) may need to verify
     that a 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.
 This document focuses on items (1) and (3).  Providing location
 information by the ISP to emergency authorities, including PSAPs,
 regional emergency management association, and emergency personnel is
 typically a legal obligation covered by regulatory frameworks.

1.2. Location Hiding

 Internet Access Providers (IAPs) and Internet Service Providers
 (ISPs) typically have little incentive to provide location
 information to end hosts or independent VSPs (without monetary
 compensation) for any purpose, including for emergency call routing.
 The decision to deny disclosure of location information 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.  Other providers may not want

Schulzrinne, et al. Informational [Page 3] RFC 6444 Location Hiding Requirements January 2012

 to make location information available without the ability to charge
 for it.  Yet, others fear problems with regard to privacy when
 disclosing location information to potentially unknown third parties.

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 is [RFC5687].
 The requirements for obtaining an LbyR via the LCP and the
 corresponding dereferencing step can be found in [RFC5808].
 HTTP Enabled Location Delivery (HELD), see [RFC5985], 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.  These credentials allow the ISP/IAP to authenticate and
 to authorize the party that would like to request location
 information.  The policy to obtain these credentials allows ISPs/IAPs
 to put constraints under which these credentials are handed out.
 ISPs/IAPs ideally might want to engage in a business relationship
 with the VSP to receive a financial compensation for the service they
 provide.  On the Internet, the number of VSPs is potentially large
 and the VSPs would not want to enter a business contract with
 potentially every ISP/IAP worldwide.  The number of potential
 contracts between ISPs/IAPs and PSAPs is, however, relatively small
 as they typically need to have a local relationship as PSAPs provide
 their emergency services support in a certain geographical region for
 which certain ISPs/IAPs have networks deployed.
 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.  Since LoST [RFC5222] requires location by value, location
 by reference cannot be used for location-based routing.  Also, LoST
 servers may be operated by independent parties, including VSPs, which
 again may not be able to resolve the reference to location by value.
 (Note that LoST is a protocol used for determining the location-
 appropriate PSAP based on location information and a Service URN
 [RFC5031].)

Schulzrinne, et al. Informational [Page 4] RFC 6444 Location Hiding Requirements January 2012

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 [RFC5687].

3. Requirements

 Req-1:   There MUST be a way for the ISP/IAP to withhold precise
          location information from the endpoint and from the VSP.
 Req-2:   The ISP/IAP MUST support the ability of the endpoint or the
          VSP to route emergency calls.
 Req-3:   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.  This requirement is provided to deal
          with potential security problems described in Section 5.1 of
          [RFC5069].
 Req-4:   The PSAP MUST receive precise location information (by
          value) about emergency callers.  As such, any solution MUST
          be able to provide location information to the PSAP even
          while withholding it from the emergency caller.
 Req-5:   The proposed solution MUST NOT assume a business or trust
          relationship between the caller's VSP and the caller's ISP.
 Req-6:   A solution MUST consider deployment scenarios where a VSP
          does not operate in the same jurisdiction as the PSAP.
 Req-7:   The solution MUST consider that service boundaries for the
          various emergency services responsible for a particular
          location may differ.
 Req-8:   The steps needed by the endpoint for emergency calling
          SHOULD be no different when location is withheld versus when
          location is not withheld.  In particular, user agents cannot
          require additional configuration to discover in which
          particular environment (hiding or no hiding) they find
          themselves.

Schulzrinne, et al. Informational [Page 5] RFC 6444 Location Hiding Requirements January 2012

 Req-9:   The solution SHOULD work without the ISP/IAP having to
          support SIP and without the need to utilize SIP between the
          endpoint and the VSP.
 Req-10:  The solution MUST work if PSAP boundaries have holes.  (For
          a discussion about holes in PSAP boundaries and their
          encoding, the reader is referred to [RFC5964].)
 Req-11:  The solution MUST NOT assume the existence of Emergency
          Service Routing Proxies (ESRPs) per country, state, and
          city.
 Req-12:  The solution MUST consider that service boundaries for
          different emergency services may differ, but they overlap at
          the location of the caller.
 Req-13:  Though the solution MAY add steps to the emergency call
          routing process described in [RFC6443], 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-14:  The solution MUST allow the end host to determine PSAP/ESRP
          URLs prior to the call, for all emergency services.
 Req-15:  The solution MUST allow user agents (UAs) to discover at
          least their dial string ahead of the emergency call.
 Req-16:  The solution MUST have minimal impact on UAs, i.e., a
          solution is preferred if it does not require a substantially
          different emergency service procedure compared to the
          procedure of dealing with emergency services where no
          location hiding is applied.
 Req-17:  The solution MUST NOT interfere with the use of LoST for
          non-emergency services.
 Req-18:  The solution MUST allow emergency calls to reach an IP-to-
          PSTN gateway rather than the IP-based PSAP directly.
 Req-19:  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.
 Req-20:  The solution SHOULD minimize the impact on LoST, SIP
          conveyance [RFC6442], and DHCP.

Schulzrinne, et al. Informational [Page 6] RFC 6444 Location Hiding Requirements January 2012

 Req-21:  The solution SHOULD NOT break in the presence of NATs and
          SHOULD consider the presence of legacy devices, as described
          in [RFC5687].

4. Security Considerations

 This document does not raise additional security consideration beyond
 those mentioned in [RFC5687] and discussed in this document.

5. 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)
 The authors would also like to thank Ben Campbell for his Gen-ART
 review.  Additionally, we would like to thank Jari Arkko, Alexey
 Melnikov, Tim Polk, and Dan Romascanu for their IESG review.

6. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC5031]  Schulzrinne, H., "A Uniform Resource Name (URN) for
            Emergency and Other Well-Known Services", RFC 5031,
            January 2008.
 [RFC5069]  Taylor, T., Tschofenig, H., Schulzrinne, H., and M.
            Shanmugam, "Security Threats and Requirements for
            Emergency Call Marking and Mapping", RFC 5069,
            January 2008.
 [RFC5222]  Hardie, T., Newton, A., Schulzrinne, H., and H.
            Tschofenig, "LoST: A Location-to-Service Translation
            Protocol", RFC 5222, August 2008.

Schulzrinne, et al. Informational [Page 7] RFC 6444 Location Hiding Requirements January 2012

 [RFC5687]  Tschofenig, H. and H. Schulzrinne, "GEOPRIV Layer 7
            Location Configuration Protocol: Problem Statement and
            Requirements", RFC 5687, March 2010.
 [RFC5808]  Marshall, R., "Requirements for a Location-by-Reference
            Mechanism", RFC 5808, May 2010.
 [RFC5964]  Winterbottom, J. and M. Thomson, "Specifying Holes in
            Location-to-Service Translation (LoST) Service
            Boundaries", RFC 5964, August 2010.
 [RFC5985]  Barnes, M., "HTTP-Enabled Location Delivery (HELD)",
            RFC 5985, September 2010.
 [RFC6442]  Polk, J., Rosen, B., and J. Peterson, "Location Conveyance
            for the Session Initiation Protocol", RFC 6442,
            December 2011.
 [RFC6443]  Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,
            "Framework for Emergency Calling Using Internet
            Multimedia", RFC 6443, December 2011.

Schulzrinne, et al. Informational [Page 8] RFC 6444 Location Hiding Requirements January 2012

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: L.Liess@telekom.de
 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

Schulzrinne, et al. Informational [Page 9]

/data/webs/external/dokuwiki/data/pages/rfc/rfc6444.txt · Last modified: 2012/01/04 22:50 by 127.0.0.1

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki