Internet DRAFT - draft-winterbottom-ecrit-priv-loc
draft-winterbottom-ecrit-priv-loc
ECRIT J. Winterbottom
Internet-Draft Winterb Consulting Services
Updates: RFC6881 (if approved) H. Tschofenig
Intended status: Standards Track
Expires: November 30, 2014 L. Liess
Deutsche Telekom
May 29, 2014
A Routing Request Extension for the HELD Protocol
draft-winterbottom-ecrit-priv-loc-04.txt
Abstract
In many circumstances public LoST servers or a distributed network of
forest guides linking public LoST servers is not available. In such
environments the general ECRIT calling models breakdown. However,
location servers operating in these areas are often privy to the
necessary information to reach emergency and other services. This
document describes a solution where by the routing information may be
obtained from a location server using a simple extension to the HELD
protocol.
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
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 30, 2014.
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
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. HELD Schema Extension . . . . . . . . . . . . . . . . . . . . 8
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 10
8. Security Considerations . . . . . . . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
9.1. URN sub-namespace registration for
'urn:ietf:params:xml:ns:geopriv:held:ri' . . . . . . . . . 11
9.2. XML Schema Registration . . . . . . . . . . . . . . . . . 11
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
In many circumstances public LoST [RFC5222] servers or a distributed
network of forest guides linking public LoST servers is not
available. In such environments the general ECRIT calling models
breakdown. Location servers operating in these areas are often privy
to the necessary information to reach emergency and other services.
This document describes how adding an extension to the HELD protocol
[RFC5985] can used to extract this information for a location
information server in the absence of a LoST server or network of
forest guides.
2. Terminology
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 in [RFC2119].
The terms LIS, ESRP, VSP and PSAP are used as defined in [RFC6443].
The term "Access Network Provider" is used as defined in [RFC5687]
and incompasses both the Internet Access Provider (IAP) and Internet
Service Provider (ISP).
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3. Motivation
The Internet emergency calling architecture specified in [RFC6881]
describes two main models for emergency call processing. The first
is a device-centric model, where a device obtains location
information using a location configuration protocol, such a HELD
[RFC5985], and then proceeds to determine the address of the next hop
closer to the local PSAP using LoST [RFC5222]. Figure 1 shows this
model in a simplified form.
+---Location Request---+
| (1) |
+---+----+ +---V---+
| |<--Location--| LIS |
| Caller | (2) +-------+ +--------+
| | | ESRP/ |
| |----Find Service-------+ | PSAP |
+------^-+ (3) | +--------+
| | +--------V----+ ^
| +-----Service----| LoST Server | |
| (4) +-------------+ +---+---+
+-------------Call Initiation------------>| VSP |
(5) +-------+
Figure 1: Device-Centric Emergency Services Model
The second approach is a softswitch-centric model, where a device
initiates and emergency call and the serving softswitch detects that
the call is an emergency and initiates retrieving the caller's
location from a Location Information Server (LIS) using HELD
[RFC5985] with identity extensions [RFC6155] [RFC6915] and then
determining the route to the local PSAP using LoST [RFC5222].
Figure 2 shows the high-level protocol interactions.
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+---Location Request---+
| (2) |
+---V---+ |
| LIS | |
+----+--+ +----+----+
| | |
+----Location--->| Soft |
+--------+ (3) | Switch |
| Caller |------Call Initiation------------> | |
+--------+ (1) +-+-^---+-+
+-------------+ | | |
| LoST Server |<-Find Service--+ | |
+------+------+ (4) | |
| | |
+----------Service--------+ |
(5) |
+-----------+ |
| ESRP/PSAP |<------Call----+
+-----------+ (6)
Figure 2: Softswitch-Centric Calling Model
In the softswitch-centric model when a VSP receives an emergency call
it performs two tasks. The first task is to determine the correct
LIS to ask for location information, this is done using a combination
of reverse DNS lookup described in [RFC7216] to acquire the serving
domain name and then using [RFC5986] to determine the LIS URI. Once
the location is obtained from the LIS, the VSP determines the LoST
server associated with the domain serving the caller and queries it
for the correct PSAP address.
LoST server discovery is a domain based activity, similar to the LIS
discovery technique. However, unlike the LIS that is a domain bound
service, a LoST server is a geographically bound service. This means
that for a domain that spans multiple geographic regions the LoST
server determined may not be able to provide a route to the necessary
PSAP. When this occurs, the contacted LoST server invokes the help
of other LoST servers and this requires the deployment of forest
guides.
At the time of writing, several countries have expressed their
reluctance to deploy public LoST servers. In countries amenable to
use of LoST and forest guides no public forest guides have been
deployed. There appears little interest from the public sector in
establishing a global forest guide network. These issues pose
threats to both the device-centric and the softswitch-centric calling
approaches in terms of them operating everywhere.
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The device-centric and softswitch-centric calling models both involve
the notion of a LIS bound to the serving access network. In many
cases the LIS already knows the destination PSAP address for any
given location. In [RFC6881] for example, the LIS validates all
civic locations using a location validation procedure. This
procedure is the same as a routing request and so the LIS has the
resulting the PSAP routing information. In other cases, the LIS
knows the correct PSAP for a given location at provisioning time, or
the access network might always route to the same emergency provider.
Irrespective of the way in which the LIS learns the PSAP address for
a location, the LIS will, in a great many cases, have this
information.
This document specifies an extension to the HELD protocol so that
emergency routing information can be requested from the LIS at the
same time that location information is requested. The document
updates [RFC6881] by requiring devices and softswitches that
understand this specification to always request routing information
to avoid the risk of query failure where no LoST server or forest
guide network is deployed.
4. Mechanism
The mechanism consists of adding an element to the HELD
locationRequest and an element to the locationResponse. The request
element indicates that the requestor wants the LIS to provide routing
information for the location where the device is. If the LIS
understands the routing request and has routing information
accessible it provides the information in a routingInformation
element included in the locationResponse. How the LIS obtains this
information is left to implementation, one possible option is that
the LIS acquires it from a LoST server, other possibilities are
described in Section 3.
A LIS that does not understand the routing request element ignores it
and returns location as normal.
A LIS that does understand the routing request element but can't
obtain routing information returns location as normal.
The routing information in the location response consists of one or
more service elements which is identified by a service name. The
service name is a URI and might contain a general emergency service
urn such as urn:service:sos or might contain a specific service urn.
For each service name a list of one or more service destinations is
provided. Each destination is expressed as a URI and each URI scheme
should only appear once in this list. The routing information is
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intended to be used at the time it is received. To avoid any risks
of using stale routing information the value should not be cached by
the receiving entity.
Reusing the mapping element from the LoST findServiceResponse message
to provide the routing information was considered. However, this
would have meant that several of the mandatory components in the
mapping element would have had to contain ambiguous or misleading
values. Specifically, the "source" attribute is required to contain
a LoST application unique string for the authoritative server.
However, in the situations described in this specification there may
not be an authoritative LoST server, so any value put into this
attribute would be misleading. In addition to this, routing
information received in the manner described in this specification
should not be cached by the receiver, so detailing when the routing
information expires or was last updated is irrelevant.
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5. HELD Schema Extension
This section describes the schema extension to HELD.
<?xml version="1.0"?>
<xs:schema
targetNamespace="urn:ietf:params:xml:ns:geopriv:held:ri"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:eri="urn:ietf:params:xml:ns:geopriv:held:ri"
xmlns:xml="http://www.w3.org/XML/1998/namespace"
elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:element name="requestRoutingInformation">
<xs:complexType name="empty"/>
</xs:element>
<xs:complexType name="service">
<xs:complextContent>
<xs:restriction base="xs:anyType">
<xs:sequence>
<xs:element name="dest" type="xs:anyURI"
maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="seviceUri" type="xs:anyURI"
use="required"/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:element name="routingInformation" type="ri:riType"/>
<xs:complexType name="riType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:sequence>
<xs:element name="service" type="ri:service"
maxOccurs="unbounded"/>
<xs:any namespace="##other" processContents="lax"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:anyAttribute namespace="##any" processContents="lax"/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
</xs:schema>
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6. Examples
Figure 3 illustrates a <locationRequest> example that contains IP
flow information in the request.
<locationRequest xmlns="urn:ietf:params:xml:ns:geopriv:held"
responseTime="emergencyRouting">
<requestRoutingInformation
xmlns="urn:ietf:params:xml:ns:geopriv:held:ri"/>
<flow xmlns="urn:ietf:params:xml:ns:geopriv:held:flow"
layer4="tcp" layer3="ipv4">
<src>
<address>192.168.1.1</address>
<port>1024</port>
</src>
<dst>
<address>10.0.0.1</address>
<port>80</port>
</dst>
</flow>
</locationRequest>
Figure 3: Example Location Request.
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Figure 4 illustrates the <locationResponse> message containing two
location URIs: a HTTPS and a SIP URI. Additionally, the response
contains routing information.
<locationResponse xmlns="urn:ietf:params:xml:ns:geopriv:held">
<locationUriSet expires="2006-01-01T13:00:00.0Z">
<locationURI>
https://ls.example.com:9768/357yc6s64ceyoiuy5ax3o
</locationURI>
<locationURI>
sip:9769+357yc6s64ceyoiuy5ax3o@ls.example.com
</locationURI>
</locationUriSet>
<routingInformation
xmlns="urn:ietf:params:xml:ns:geopriv:held:ri">
<service serviceUri="urn:service:sos:police">
<dest>sip:nypd@example.com</dest>
<dest>sips:nypd@example.com</dest>
<dest>xmpp:nypd@example.com</dest>
</service>
<service serviceUri="urn:service:sos:fire">
<dest>sip:fd@ny.example.com</dest>
<dest>sips:fd@ny.example.com</dest>
<dest>xmpp:fd@ny.example.com</dest>
</service>
</routingInformation>
</locationResponse>
Figure 4: Example Location Response
7. Privacy Considerations
This document makes no changes that require privacy considerations
beyond those already described in [RFC5985] and [RFC6155].
8. Security Considerations
This document imposes no additional security considerations beyond
those already described in [RFC5985] and [RFC6155].
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9. IANA Considerations
9.1. URN sub-namespace registration for
'urn:ietf:params:xml:ns:geopriv:held:ri'
This document calls for IANA to register a new XML namespace, as per
the guidelines in [RFC3688].
URI: urn:ietf:params:xml:ns:geopriv:held:ri
Registrant Contact: IETF, ECRIT working group (ecrit@ietf.org),
James Winterbottom (a.james.winterbottom@gmail.com).
XML:
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>HELD Routing Information Extensions</title>
</head>
<body>
<h1>Additional Element for HELD Routing Information</h1>
<h2>urn:ietf:params:xml:ns:geopriv:held:ri</h2>
[[NOTE TO IANA/RFC-EDITOR: Please update RFC URL and replace XXXX
with the RFC number for this specification.]]
<p>See <a href="[[RFC URL]]">RFCXXXX</a>.</p>
</body>
</html>
END
9.2. XML Schema Registration
This section registers an XML schema as per the procedures in
[RFC3688].
URI: urn:ietf:params:xml:schema:geopriv:held:ri
Registrant Contact: IETF, ECRIT working group, (ecrit@ietf.org),
James Winterbottom (a.james.winterbottom@gmail.com).
The XML for this schema can be found as the entirety of Section 5
of this document.
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10. Acknowledgements
We would like to thank Wilfried Lange for sharing his views with us.
We would also like to thank Bruno Chatras for his early review
comments and Bernd Henschel for his support.
11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
January 2004.
[RFC5222] Hardie, T., Newton, A., Schulzrinne, H., and H.
Tschofenig, "LoST: A Location-to-Service Translation
Protocol", RFC 5222, August 2008.
[RFC5687] Tschofenig, H. and H. Schulzrinne, "GEOPRIV Layer 7
Location Configuration Protocol: Problem Statement and
Requirements", RFC 5687, March 2010.
[RFC5985] Barnes, M., "HTTP-Enabled Location Delivery (HELD)",
RFC 5985, September 2010.
[RFC6443] Rosen, B., Schulzrinne, H., Polk, J., and A. Newton,
"Framework for Emergency Calling Using Internet
Multimedia", RFC 6443, December 2011.
[RFC6881] Rosen, B. and J. Polk, "Best Current Practice for
Communications Services in Support of Emergency Calling",
BCP 181, RFC 6881, March 2013.
11.2. Informative References
[RFC5986] Thomson, M. and J. Winterbottom, "Discovering the Local
Location Information Server (LIS)", RFC 5986,
September 2010.
[RFC6155] Winterbottom, J., Thomson, M., Tschofenig, H., and R.
Barnes, "Use of Device Identity in HTTP-Enabled Location
Delivery (HELD)", RFC 6155, March 2011.
[RFC6915] Bellis, R., "Flow Identity Extension for HTTP-Enabled
Location Delivery (HELD)", RFC 6915, April 2013.
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[RFC7216] Thomson, M. and R. Bellis, "Location Information Server
(LIS) Discovery Using IP Addresses and Reverse DNS",
RFC 7216, April 2014.
Authors' Addresses
James Winterbottom
Winterb Consulting Services
Gwynneville, NSW 2500
AU
Phone: +61 448 266004
Email: a.james.winterbottom@gmail.com
Hannes Tschofenig
Halls in Tirol 6060
Austria
Phone:
Email: Hannes.Tschofenig@gmx.net
URI: http://www.tschofenig.priv.at
Laura Liess
Deutsche Telekom Networks
Deutsche Telekom Allee 7
Darmstadt, Hessen 64295
Germany
Phone:
Email: L.Liess@telekom.de
URI: http://www.telekom.de
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