One document matched: draft-schulzrinne-ecrit-unauthenticated-access-00.txt
ECRIT H. Schulzrinne
Internet-Draft Columbia University
Updates: S. McCann
draft-ietf-ecrit-framework; Siemens/Roke Manor Research
draft-ietf-ecrit-phonebcp G. Bajko
(if approved) Nokia
Intended status: Standards Track H. Tschofenig
Expires: February 20, 2008 Nokia Siemens Networks
August 19, 2007
Extensions to the Emergency Services Architecture for dealing with
Unauthenticated and Unauthorized Devices
draft-schulzrinne-ecrit-unauthenticated-access-00.txt
Status of this Memo
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Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
The IETF emergency services architecture assumes that access to a
network has already happened using the traditional network access
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authentication procedures or that no authentication for network
access is needed (e.g., in case of public hotspots). Subsequent
protocol interactions, such as obtaining location information,
learning the address of the Public Safety Answering Point (PSAP) and
the emergency call itself are largely decoupled from the underlying
network access procedures.
There are, however, cases where a device is not in possession of
credentials for network access, does not have a VoIP provider, or
where the credentials are available but became invalid due to various
reasons (e.g., credit exhaustion, expired accounts, etc.).
This document provides a problem statement, introduces terminology
and describes an extension for the base IETF emergency services
architecture.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1. End Host Profile . . . . . . . . . . . . . . . . . . . . . 9
4.1.1. ESRP Discovery . . . . . . . . . . . . . . . . . . . . 9
4.1.2. Location Determination and Location Configuration . . 9
4.1.3. Emergency Call Identification . . . . . . . . . . . . 9
4.1.4. SIP Emergency Call Signaling . . . . . . . . . . . . . 9
4.1.5. Media . . . . . . . . . . . . . . . . . . . . . . . . 10
4.1.6. Testing . . . . . . . . . . . . . . . . . . . . . . . 11
4.2. ISP Profile . . . . . . . . . . . . . . . . . . . . . . . 11
4.2.1. ESRP Discovery . . . . . . . . . . . . . . . . . . . . 11
4.2.2. Location Determination and Location Configuration . . 11
4.2.3. Emergency Call Routing . . . . . . . . . . . . . . . . 11
4.2.4. Emergency Call Identification . . . . . . . . . . . . 12
4.2.5. SIP Emergency Call Signaling . . . . . . . . . . . . . 12
4.2.6. Quality of Service . . . . . . . . . . . . . . . . . . 12
4.3. PSAP Profile . . . . . . . . . . . . . . . . . . . . . . . 12
4.3.1. Location Retrieval . . . . . . . . . . . . . . . . . . 12
4.3.2. Emergency Call Routing . . . . . . . . . . . . . . . . 12
4.3.3. Emergency Call Identification . . . . . . . . . . . . 13
4.3.4. SIP Emergency Call Signaling . . . . . . . . . . . . . 13
4.3.5. Media . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3.6. Testing . . . . . . . . . . . . . . . . . . . . . . . 13
5. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
8. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . . . . 20
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1. Introduction
Summoning police, the fire department or an ambulance in emergencies
is one of the fundamental and most-valued functions of the telephone.
As telephone functionality moves from circuit-switched telephony to
Internet telephony, its users rightfully expect that this core
functionality will continue to work at least as well as it has for
the older technology. New devices and services are being made
available that could be used to make a request for help, which are
not traditional telephones, and users are increasingly expecting them
to be used to place emergency calls.
Based on the communication model of the Session Initiation Protocol
(SIP) as excerised in the IETF it is not necessary to deploy SIP
entities in access networks (or associated to them). Instead, VoIP
provider may deploy their SIP entities at any place on the Internet.
The IETF emergency services architecture acknowledges this deployment
model and even goes a step further by recognizing that there are
potentially other, non-SIP VoIP provider, that might want to offer
emergency service support to their customers. Hence, the interaction
between a SIP User Agent and its VoIP provider does not need to be
standarized although [I-D.ietf-ecrit-phonebcp] provides best current
practise recommendations regarding the usage of certain features as
excerised in the case of SIP.
This flexibility has implications for the architecture, as briefly
described in [I-D.tschofenig-ecrit-architecture-overview], but allows
access networks to be application layer agnostic. Furthermore, since
the normal VoIP communication exchanges do not traverse these
entities in the access network it is quite likely that
interoperability problems will occur especially in an emergency case.
There are essentially three environments that need to be considered:
1. The emergency caller does not credentials for access to the
network but it still has credentials for his VoIP provider.
This is often the case with enterprise networks, home networks,
or governmental networks. In other cases the user might be able
to obtain such credentials, for example in hotspots found in
hotels, at airports, and in many coffee shops. Unfortunately,
users have to go through a lengthy procedure (often involving
captive portals) to obtain a temporary account in exchange of
money. In emergency situations it is certainly not desirable to
let the user find their way through a number of webpages and to
type-in their credit card details.
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2. The emergency caller has credentials for network access but does
not have credentials for a VoIP provider. This case is rather
unlikely.
3. The emergency caller has credentials (for either network access
or it's VoIP provider) but they do not provide enough
authorization to make a call. This use case essentially refers
to lack of authorization. Examples are: Insufficient credits,
lack of a roaming agreement (between visited network and home
network), disabled account, and other authorization failures.
Scenario (1) is the most likely scenario and the main focus of this
document.
In all these cases it is not possible to place an emergency call as
envisioned in the IETF emergerency services architecture, described
in [I-D.ietf-ecrit-framework].
Note that at the time of writing there is currently no regulation in
place that demands the functionality described in this memo. Since
many SDOs have started their work on this subject in a proactive
fashion in the anticipation that national regulation in some
countries might demand this functionality for a subset of network
types.
2. Terminology
In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119
[RFC2119].
This document introduces new terminology:
Unauthenticated Emergency Service: We use this term in this document
to refer to all the cases where the emergency caller does not have
credentials or are not authorized to access a network. This also
includes cases where a device is not in possession of credentials
for network access, does not have a VoIP provider (as it is the
case for uninitialized phones), or where the credentials are
available but became invalid due to various reasons (e.g., credit
exhaustion, expired accounts, etc.).
This document reuses terminology from [I-D.ietf-geopriv-l7-lcp-ps]
and [I-D.ietf-ecrit-requirements].
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3. Architecture
For unauthenticated emergency services support it is insufficient to
provide mechanisms only at the link layer in order to bypass
authentication. A modification to the emergency services
architecture is necessary since the IAP and the ISP need to make sure
that the claimed emergency caller indeed performs an emergency call
rather than using the network for other purposes, and thereby acting
fraudulent by skipping any authentication, authorization and
accounting procedures. Hence, without introducing some understanding
of the specific application the ISP (and consequently the IAP) will
not be able to detect and filter malicious activities. This leads to
the architecture described in Figure 1 where the IAP needs to
implement extensions to link layer procedures for unauthenticated
emergency service access and the ISP needs to deploy emergency
services related entities used for call routing, such as the
Emergency Services Routing Proxy (ESRP), a Location Configuration
Server (LCS) and a mapping database.
On a very high-level, the interaction is as follows starting with the
end host not being attached to the network and the user starting to
make an emergency call.
o Some radio networks have added support for unauthenticated
emergency access, some other type of networks advertise these
capabilities using layer beacons. The end host learns about these
unauthenticated emergency services capabilities either from the
link layer type or from advertisement.
o The end host uses the link layer specific network attachment
procedures defined for unauthenticated network access in order to
get access to emergency services.
o When the link layer network attachment procedure is completed the
end host learns basic configuration information using DHCP from
the ISP, including the address of the ESRP, as shown in (2).
o When the IP address configuration is completed then the SIP UA
initiates a SIP INVITE towards the indicated ESRP, as shown in
(3). The INVITE message contains all the necessary parameters
required by Section 4.1.4.
o The ESRP receives the INVITE and processes it according to the
description in Section 4.2.5. The location of the end host may
need to be determined using a protocol interaction shown in (4).
o Potentially, an interaction between the LCS of the ISP and the LCS
of the IAP may be necessary, see (5).
o Finally, the correct PSAP for the location of the end host has to
be evaluated, see (6).
o The ESRP routes the call to the PSAP, as shown in (7).
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o The PSAP evaluates the initial INVITE and acts according to SIP
and the description in Section 4.3.4 in order to complete the call
setup.
o Finally, when the call setup is completed media traffic can be
exchanged between the PSAP operator and the emergency caller,
according to Section 4.3.5 and Section 4.1.5.
For editorial reasons the end-to-end SIP and media exchange between
the PSAP and SIP UA are not shown in Figure 1.
Two important aspects are worth to highlight:
o The IAP/ISP needs to understand the concept of emergency calls and
the SIP profile described in this document. No other VoIP
protocol profile, such as XMPP, Skype, etc., are supported for
emergency calls in this particular architecture. Other profiles
may be added in the future, but the deployment effort is enormous
since they have to be universally deployed.
o The end host has no obligation to determine location information.
It may attach location information if it has location available
(e.g., from a GPS receiver).
Figure 1 shows that the ISP needs to deploy SIP-based emergency
services functionality. It is important to note that the ISP itself
may outsource the functionality by simply providing access to them
(e.g., it puts the IP address of an ESRP or a LoST server into an
allow-list). For editorial reasons this outsourcing is not shown.
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+---------------------------+
| |
| Emergency Network |
| Infrastructure |
| |
| +----------+ +----------+ |
| | PSAP | | ESRP | |
| | | | | |
| +----------+ +----------+ |
+-------------------^-------+
|
| (7)
+------------------------+-----------------------+
| ISP | |
| | |
|+----------+ v |
|| Mapping | (6) +----------+ |
|| Database |<----->| ESRP / | |
|+----------+ | SIP Proxy|<-+ |
|+----------+ +----------+ | +----------+|
|| LCS-ISP | ^ | | DHCP ||
|| |<---------+ | | Server ||
|+----------+ (4) | +----------+|
+-------^-------------------------+-----------^--+
+-------|-------------------------+-----------|--+
| IAP | (5) | | |
| V | | |
|+----------+ | | |
|| LCS-IAP | +----------+ | | |
|| | | Link | |(3) | |
|+----------+ | Layer | | | |
| | Device | | (2)| |
| +----------+ | | |
| ^ | | |
| | | | |
+------------------------+--------+-----------+--+
| | |
(1)| | |
| | |
| +----+ |
v v |
+----------+ |
| End |<-------------+
| Host |
+----------+
Figure 1: Unauthenticated Emergency Services Architecture
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4. Profile
4.1. End Host Profile
4.1.1. ESRP Discovery
The end host MUST use the "Dynamic Host Configuration Protocol (DHCP-
for-IPv4) Option for Session Initiation Protocol (SIP) Servers"
[RFC3361] (for IPv6) and / or the "Dynamic Host Configuration
Protocol (DHCPv6) Options for Session Initiation Protocol (SIP)
Servers" [RFC3319]. This SIP proxy located in the ISP network will
be used as the ESRP for routing emergency calls. There is no need to
discovery a separate SIP proxy with specific emergency call
functionality since the internal procedure for emergency call
processing is subject of ISP internal operation.
4.1.2. Location Determination and Location Configuration
There is no requirement for end hosts to support any Location
Configuration Protocol. If clients are in possession of location
information, for example, based on a built-in GPS receiver then they
SHOULD attach the location information in a PIDF-LO. When
constructing the PIDF-LO the guidelines in PIDF-LO profile
[I-D.ietf-geopriv-pdif-lo-profile] MUST be followed. For civic
location information the format defined in
[I-D.ietf-geopriv-revised-civic-lo] MUST be supported.
4.1.3. Emergency Call Identification
To determine which calls are emergency calls, some entity needs to
map a user entered dialstring into this URN scheme. A user may
"dial" 1-1-2, but the call would be sent to urn:service:sos. This
mapping SHOULD performed at the endpoint device, but MAY be performed
at an intermediate entity.
End host MUST use the Service URN mechanism
[I-D.ietf-ecrit-service-urn] to mark calls as emergency calls for
their home emergency dial string. For visited emergency dial string
the translation into a the Service URN mechanism is not mandatory
since the ESRP in the ISPs network knows the visited emergency dial
strings.
4.1.4. SIP Emergency Call Signaling
SIP signaling capabilities [RFC3261] are mandated for end hosts.
The initial SIP signaling method is an INVITE.
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1. The To: MUST be either a service URN in the "sos" tree or the
visited emergency dial string. [I-D.rosen-iptel-dialstring] with
the dialed digits. The sips URI [RFC3261] MUST NOT be used.
2. The From: header MUST be present and SHOULD be the AoR of the
caller, if available.
3. A Via: header MUST be present and SHOULD include the URI of the
device
4. A Route header SHOULD be present with the service URN in the
"sos" tree, and the loose route parameter.
5. A Contact header MUST be present, which might contain a GRUU
[I-D.ietf-sip-gruu], to permit an immediate call-back to the
specific device that placed the emergency call.
6. Other headers MAY be included as per normal sip behavior
7. A Supported: header MUST be included with the 'geolocation'
option tag [I-D.ietf-sip-location-conveyance], if the device
understands the concept of SIP Location. In case that the device
understands the SIP Location Conveyance
[I-D.ietf-sip-location-conveyance] extension and has its location
available, it MUST include location by-value. In this case, the
INVITE contains a Supported header with a "geolocation" option
tag, and a "cid-URL" [RFC2396] as the value in the Geolocation
header, indicating which message body part contains the PIDF-LO.
SIP Location Conveyance also requires that the UA MUST support
multipart message bodies, since SDP will likely be also in the
INVITE.
8. A normal SDP offer SHOULD be included in the INVITE. The offer
MUST include the G.711 codec.
4.1.5. Media
End points MUST send and receive media streams on RTP [RFC3550]. The
SIP offer/answer [RFC3264] negotiations MUST be used to agree on the
media streams to be used.
End points supporting voice MUST support G.711 A law (and mu Law in
North America) encoded voice as described in [RFC3551]. It is
desirable to support wideband codecs in the offer. Silence
suppression (Voice Activity Detection methods) MUST NOT be used on
emergency calls.
End points SHOULD support Instant Messaging using either [RFC3428] or
[RFC3920]. End points SHOULD support real-time text [RFC4103]. The
expectations for emergency service support for the real-time text
medium, described in [I-D.ietf-sipping-toip], Section 7.1 SHOULD be
fulfilled.
Video may be important to support Video Relay Service (Sign language
interpretation). End points supporting video MUST support H.264 per
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[RFC3984]. Support for video, instant messaging and real-time text
is optional.
4.1.6. Testing
The description in Section 9 of [I-D.ietf-ecrit-phonebcp] is
applicable to this document as well.
4.2. ISP Profile
4.2.1. ESRP Discovery
The ISP MUST implement the server side part of "Dynamic Host
Configuration Protocol (DHCP-for-IPv4) Option for Session Initiation
Protocol (SIP) Servers" [RFC3361] (for IPv6) and / or the "Dynamic
Host Configuration Protocol (DHCPv6) Options for Session Initiation
Protocol (SIP) Servers" [RFC3319].
4.2.2. Location Determination and Location Configuration
The ISP must perform the necesary steps to determine the location of
the end host. It is not necessary to standardize a specific
mechanism.
The usage of HELD [I-D.ietf-geopriv-http-location-delivery] with the
identity extensions
[I-D.winterbottom-geopriv-held-identity-extensions] may be a possible
choice. It might be necessary for the ISP to talk to the IAP in
order to determine the location of the end host. The work on LIS-to-
LIS communication may be relevant, see
[I-D.winterbottom-geopriv-lis2lis-req].
The ESRP (or a associated entity making location information
available to the PSAP) MUST understand the PIDF-LO format [RFC4119],
the PIDF-LO profile [I-D.ietf-geopriv-pdif-lo-profile] and the
revised civic format [I-D.ietf-geopriv-revised-civic-lo].
Note that this architecture also fulfills the requirements for
location hiding, see
[I-D.schulzrinne-ecrit-location-hiding-requirements].
4.2.3. Emergency Call Routing
The ISP must route the emergency call to the PSAP responsible for the
physical location of the end host. However, a standardized approach
for determining the correct PSAP based on a given location may not be
necessary.
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For cases where a standardized protocol should be used LoST
[I-D.ietf-ecrit-lost] is a suitable mechanism.
4.2.4. Emergency Call Identification
The ESRP MUST understand the Service URN mechanism
[I-D.ietf-ecrit-service-urn] (i.e., the 'urn:service:sos' tree) and
additionally the national emergency dial strings. The ESRP SHOULD
perform a mapping of national emergency dial strings to Service URNs
to simplify processing at PSAPs.
4.2.5. SIP Emergency Call Signaling
SIP signaling capabilities [RFC3261] are mandated for the ESRP. The
ESRP MUST process the messages sent by the client, as indicated in
Section 4.1.4. Furthemore, the ESRP MUST be able to add a reference
to location information, as described in SIP Location Conveyance
[I-D.ietf-sip-location-conveyance], before forwarding the call to the
PSAP. The ISP MUST be prepared to receive incoming dereferencing
requests to resolve the reference to the location information.
4.2.6. Quality of Service
The ISP may provide QoS mechanisms to ensure the preferential
treatment of emergency calls. The specific mechanisms depend on the
network, may not require standardization and are outside the scope of
this document.
4.3. PSAP Profile
4.3.1. Location Retrieval
The PSAP MUST act according to SIP Location Conveyance when
processing a request with location information. In particular, it
MUST understand PIDF-LO format [RFC4119], the PIDF-LO profile
[I-D.ietf-geopriv-pdif-lo-profile] and the revised civic format
[I-D.ietf-geopriv-revised-civic-lo]. Furthermore, the PSAP MUST
understand the SIP or SIPS dereference scheme.
4.3.2. Emergency Call Routing
There might be additional emergency call routing applied within the
PSAP operators network. This aspect is, however, outside the scope
of this document.
LoST [I-D.ietf-ecrit-lost] might be an appropriate way to determine
the next ESRP or the final PSAP for routing the emergency call.
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4.3.3. Emergency Call Identification
The ESRP MUST understand the Service URN mechanism
[I-D.ietf-ecrit-service-urn] (i.e., the 'urn:service:sos' tree) and
SHOULD understand national emergency dial strings.
4.3.4. SIP Emergency Call Signaling
SIP signaling [RFC3261] is expected be supported by the PSAP. The
ESRP MUST process the messages sent by the client, as indicated in
Section 4.1.4. When receiving an emergency call the ESRP will
dereference the reference to location information for dispatch. It
MUST use the SIP or SIPS derefencing scheme todo so.
4.3.5. Media
PSAPs MUST send and receive media streams on RTP [RFC3550]. The SIP
offer/answer [RFC3264] negotiations MUST be used to agree on the
media streams to be used.
PSAPs supporting voice MUST support G.711 A law (and mu Law in North
America) encoded voice as described in [RFC3551]. It is desirable to
support wideband codecs in the offer. Silence suppression (Voice
Activity Detection methods) MUST NOT be used on emergency calls.
Depending on national regulations PSAPs MAY need to support Instant
Messaging. If they need to provide this support then they MUST us
either [RFC3428] or [RFC3920].
Depending on national regulations PSAPs MAY need to support real-time
text [RFC4103]. If they need to provide this support then they MUST
fulfill Section 7.1 of [I-D.ietf-sipping-toip].
Depending on national regulations PSAPs MAY need to video support for
Video Relay Service (Sign language interpretation). If they need to
provide this support then they MUST support H.264 per [RFC3984].
4.3.6. Testing
The description in Section 9 of [I-D.ietf-ecrit-phonebcp] is
applicable to this document as well.
5. Example
[Editor's Note: A WLAN hotspot or a DSL home network example could go
in here.]
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6. Security Considerations
The security threats discussed in [I-D.ietf-ecrit-security-threats]
are applicable to this document. A number of security
vulnerabilities discussed in [I-D.barnes-geopriv-lo-sec] around faked
location information are less problematic in this case since location
information does not need to be provided by the end host itself or it
can be verified to fall within a specific geographical area.
There are a couple of new vulnerabilities raised with unauthenticated
emergency services since the PSAP operator does is not in possession
of any identity information about the emergency call via the
signaling path itself. In countries where this functionality is used
for GSM networks today this has lead to a significant amount of
misuse (see [reference-to-be-added]).
The link layer mechanisms need to provide a special way of handling
unauthenticated emergency services. Although this subject is not a
topic for the IETF itself but there are at least a few high-level
assumptions that may need to be collected. This includes security
features that may be desireable.
7. Acknowledgments
We would like to thank the authors of [I-D.ietf-ecrit-phonebcp]
(James Polk and Brian Rosen) for their good work. This document
makes heavy use of their document.
From an editorial point of view a lot of text in this document can be
replaced by references to [I-D.ietf-ecrit-phonebcp]. In order todo
so it is necessary to make the text in that document easier to
reference. This is subject of ongoing work.
8. Open Issues
The following three high-level topics have been determined as open
issues:
o NAT Traversal: A certain NAT traversal story needs to be described
and mandated. Most likely ICE for both the PSAP and the end host.
o A DNS-based discovery procedure that discovers an ESRP in the
local access network may need to be provided.
o Text about link layer requirements are missing. These are
necessary to make the "big picture" complete.
9. References
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9.1. Normative References
[I-D.ietf-sip-location-conveyance]
Polk, J. and B. Rosen, "Location Conveyance for the
Session Initiation Protocol",
draft-ietf-sip-location-conveyance-08 (work in progress),
July 2007.
[I-D.ietf-ecrit-service-urn]
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.
[RFC4776] Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCPv4 and DHCPv6) Option for Civic Addresses
Configuration Information", RFC 4776, November 2006.
[RFC3825] Polk, J., Schnizlein, J., and M. Linsner, "Dynamic Host
Configuration Protocol Option for Coordinate-based
Location Configuration Information", RFC 3825, July 2004.
[RFC4119] Peterson, J., "A Presence-based GEOPRIV Location Object
Format", RFC 4119, December 2005.
[I-D.ietf-geopriv-pdif-lo-profile]
Tschofenig, H., "GEOPRIV PIDF-LO Usage Clarification,
Considerations and Recommendations",
draft-ietf-geopriv-pdif-lo-profile-08 (work in progress),
July 2007.
[I-D.ietf-geopriv-revised-civic-lo]
Thomson, M. and J. Winterbottom, "Revised Civic Location
Format for PIDF-LO",
draft-ietf-geopriv-revised-civic-lo-05 (work in progress),
February 2007.
[RFC3361] Schulzrinne, H., "Dynamic Host Configuration Protocol
(DHCP-for-IPv4) Option for Session Initiation Protocol
(SIP) Servers", RFC 3361, August 2002.
[RFC3319] Schulzrinne, H. and B. Volz, "Dynamic Host Configuration
Protocol (DHCPv6) Options for Session Initiation Protocol
(SIP) Servers", RFC 3319, July 2003.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
Schulzrinne, et al. Expires February 20, 2008 [Page 15]
Internet-Draft Unauthenticated Emergency Service August 2007
June 2002.
[I-D.rosen-iptel-dialstring]
Rosen, B., "Dialstring parameter for the Session
Initiation Protocol Uniform Resource Identifier",
draft-rosen-iptel-dialstring-05 (work in progress),
March 2007.
[I-D.ietf-sip-gruu]
Rosenberg, J., "Obtaining and Using Globally Routable User
Agent (UA) URIs (GRUU) in the Session Initiation Protocol
(SIP)", draft-ietf-sip-gruu-14 (work in progress),
June 2007.
[RFC2396] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", RFC 2396,
August 1998.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264,
June 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003.
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551,
July 2003.
[RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C.,
and D. Gurle, "Session Initiation Protocol (SIP) Extension
for Instant Messaging", RFC 3428, December 2002.
[RFC4103] Hellstrom, G. and P. Jones, "RTP Payload for Text
Conversation", RFC 4103, June 2005.
[RFC3984] Wenger, S., Hannuksela, M., Stockhammer, T., Westerlund,
M., and D. Singer, "RTP Payload Format for H.264 Video",
RFC 3984, February 2005.
[I-D.ietf-sipping-toip]
Wijk, A. and G. Gybels, "Framework for real-time text over
IP using the Session Initiation Protocol (SIP)",
draft-ietf-sipping-toip-07 (work in progress),
August 2006.
[RFC3920] Saint-Andre, P., Ed., "Extensible Messaging and Presence
Schulzrinne, et al. Expires February 20, 2008 [Page 16]
Internet-Draft Unauthenticated Emergency Service August 2007
Protocol (XMPP): Core", RFC 3920, October 2004.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[I-D.ietf-ecrit-phonebcp]
Rosen, B. and J. Polk, "Best Current Practice for
Communications Services in support of Emergency Calling",
draft-ietf-ecrit-phonebcp-01 (work in progress),
March 2007.
9.2. Informative References
[I-D.ietf-ecrit-lost]
Hardie, T., "LoST: A Location-to-Service Translation
Protocol", draft-ietf-ecrit-lost-06 (work in progress),
August 2007.
[I-D.tschofenig-ecrit-architecture-overview]
Tschofenig, H. and H. Schulzrinne, "Emergency Services
Architecture Overview: Sharing Responsibilities",
draft-tschofenig-ecrit-architecture-overview-00 (work in
progress), July 2007.
[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-03 (work in
progress), July 2007.
[I-D.ietf-ecrit-framework]
Rosen, B., "Framework for Emergency Calling using Internet
Multimedia", draft-ietf-ecrit-framework-02 (work in
progress), July 2007.
[I-D.marshall-geopriv-lbyr-requirements]
Marshall, R., "Requirements for a Location-by-Reference
Mechanism used in Location Configuration and Conveyance",
draft-marshall-geopriv-lbyr-requirements-02 (work in
progress), July 2007.
[I-D.ietf-geopriv-http-location-delivery]
Barnes, M., "HTTP Enabled Location Delivery (HELD)",
draft-ietf-geopriv-http-location-delivery-01 (work in
progress), July 2007.
[I-D.ietf-ecrit-mapping-arch]
Schulzrinne, H., "Location-to-URL Mapping Architecture and
Schulzrinne, et al. Expires February 20, 2008 [Page 17]
Internet-Draft Unauthenticated Emergency Service August 2007
Framework", draft-ietf-ecrit-mapping-arch-02 (work in
progress), July 2007.
[I-D.ietf-ecrit-requirements]
Schulzrinne, H. and R. Marshall, "Requirements for
Emergency Context Resolution with Internet Technologies",
draft-ietf-ecrit-requirements-13 (work in progress),
March 2007.
[I-D.winterbottom-geopriv-held-identity-extensions]
Winterbottom, J. and M. Thomson, "HELD End-Point identity
Extensions",
draft-winterbottom-geopriv-held-identity-extensions-02
(work in progress), July 2007.
[I-D.winterbottom-geopriv-lis2lis-req]
Winterbottom, J. and S. Norreys, "LIS to LIS Protocol
Requirements", draft-winterbottom-geopriv-lis2lis-req-00
(work in progress), June 2007.
[I-D.ietf-ecrit-security-threats]
Taylor, T., "Security Threats and Requirements for
Emergency Call Marking and Mapping",
draft-ietf-ecrit-security-threats-04 (work in progress),
April 2007.
[I-D.schulzrinne-ecrit-location-hiding-requirements]
Schulzrinne, H., "Location Hiding: Problem Statement and
Requirements",
draft-schulzrinne-ecrit-location-hiding-requirements-00
(work in progress), July 2007.
[I-D.barnes-geopriv-lo-sec]
Barnes, R., "Threats to GEOPRIV Location Objects",
draft-barnes-geopriv-lo-sec-00 (work in progress),
July 2007.
Schulzrinne, et al. Expires February 20, 2008 [Page 18]
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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
Stephen McCann
Siemens/Roke Manor Research
Email: stephen.mccann@roke.co.uk
Gabor Bajko
Nokia
Email: Gabor.Bajko@nokia.com
Hannes Tschofenig
Nokia Siemens Networks
Otto-Hahn-Ring 6
Munich, Bavaria 81739
Germany
Email: Hannes.Tschofenig@nsn.com
URI: http://www.tschofenig.com
Schulzrinne, et al. Expires February 20, 2008 [Page 19]
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Schulzrinne, et al. Expires February 20, 2008 [Page 20]
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