ECRIT H. Schulzrinne
Internet-Draft Columbia University
Intended status: Informational L. Liess
Expires: April 15, 2009 Deutsche Telekom
H. Tschofenig
Nokia Siemens Networks
B. Stark
AT&T
A. Kuett
Skype
October 12, 2008
Location Hiding: Problem Statement and Requirements
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
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to a Public Safety Answering Point (PSAP). For determining the PSAP
Uniform Resource Identifier (URI) the usage of the 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 . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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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 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 URI [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 in three ways:
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 types of 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)) are 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. Other providers
may not want to make location information available without the
ability to charge for it.
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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.
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
3.1. High-Level Requirements
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Req-A: There 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: The PSAP MUST be provided precise location information (by
value) for emergency callers. The endpoint and/or VSP may provide
this information either by value or by reference.
3.2. Detailed Requirements
Req-1: The proposed solution MUST NOT assume a business or trust
relationship between the caller's VSP 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.
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Req-9: Though the solution MAY add steps to the emergency call
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
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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-08 (work in
progress), 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),
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-06 (work in
progress), July 2008.
[RFC5222] Hardie, T., Newton, A., Schulzrinne, H., and H.
Tschofenig, "LoST: A Location-to-Service Translation
Protocol", RFC 5222, August 2008.
[I-D.ietf-geopriv-lbyr-requirements]
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Marshall, R., "Requirements for a Location-by-Reference
Mechanism", draft-ietf-geopriv-lbyr-requirements-03 (work
in progress), July 2008.
[RFC5031] Schulzrinne, H., "A Uniform Resource Name (URN) for
Emergency and Other Well-Known Services", 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-09 (work in
progress), 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
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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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