| ECRIT | R. Gellens |
| Internet-Draft | Consultant |
| Intended status: Standards Track | H. Tschofenig |
| Expires: January 2, 2017 | Individual |
| July 1, 2016 |
Next-Generation Pan-European eCall
draft-ietf-ecrit-ecall-08.txt
This document describes how to use IP-based emergency services mechanisms to support the next generation of the Pan European in-vehicle emergency call service defined under the eSafety initiative of the European Commission (generally referred to as "eCall"). eCall is a standardized and mandated system for a special form of emergency calls placed by vehicles, providing real-time communications and an integrated set of related data.
This document also registers a MIME Content Type and an Emergency Call Additional Data Block for the eCall vehicle data and metadata/control data.
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 working documents as Internet-Drafts. The list of current Internet-Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 2, 2017.
Copyright (c) 2016 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.
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].
This document re-uses terminology defined in Section 3 of [RFC5012].
Additionally, we use the following abbreviations:
| Term | Expansion |
|---|---|
| 3GPP | 3rd Generation Partnership Project |
| CEN | European Committee for Standardization |
| EENA | European Emergency Number Association |
| ESInet | Emergency Services IP network |
| IMS | IP Multimedia Subsystem |
| IVS | In-Vehicle System |
| MNO | Mobile Network Operator |
| MSD | Minimum Set of Data |
| PSAP | Public Safety Answering Point |
This document is limited to the signaling, data exchange, and protocol needs of next-generation eCall (NG-eCall, also referred to as packet-switched eCall (PS-eCall) and all-IP eCall) within the SIP framework for emergency calls, as described in [RFC6443] and [RFC6881]. eCall itself is specified by 3GPP and CEN and these specifications include far greater scope than is covered here.
The eCall service operates over cellular wireless communication, but this document does not address cellular-specific details, nor client domain selection (e.g., circuit-switched versus packet-switched). All such aspects are the purview of their respective standards bodies. The scope of this document is limited to eCall operating within a SIP-based environment (e.g., 3GPP IMS Emergency Calling).
The technical contents of this document can be suitable for use in other vehicle-initiated emergency call systems, but this is out of scope for this document.
Vehicles designed for multiple regions might need to support eCall and other Advanced Automatic Crash Notification (AACN) systems, such as described in [I-D.ietf-ecrit-car-crash]. That system is compatible with eCall, differing primarily in the specific data set that is sent.
Emergency calls made from vehicles (e.g., in the event of a crash) assist in significantly reducing road deaths and injuries by allowing emergency services to be aware of the incident, the state of the vehicle, the location of the vehicle, and to have a voice channel with the vehicle occupants. This enables a quick and appropriate response.
The European Commission initiative of eCall was conceived in the late 1990s, and has evolved to a European Parliament decision requiring the implementation of a compliant in-vehicle system (IVS) in new vehicles and the deployment of eCall in the European Member States in the very near future. Other regions are developing eCall-compatible systems.
The pan-European eCall system provides a standardized and mandated mechanism for emergency calls by vehicles. eCall establishes procedures for such calls to be placed by in-vehicle systems, recognized and processed by the mobile network, and routed to a specialized PSAP where the vehicle data is available to assist the call taker in assessing and responding to the situation. eCall provides a standard set of vehicle, sensor (e.g., crash related), and location data.
An eCall can be either user-initiated or automatically triggered. Automatically triggered eCalls indicate a car crash or some other serious incident. Manually triggered eCalls might be reports of witnessed crashes or serious hazards. PSAPs might apply specific operational handling to manual and automatic eCalls.
Legacy eCall is standardized (by 3GPP [SDO-3GPP] and CEN [CEN]) as a 3GPP circuit-switched call over GSM (2G) or UMTS (3G). Flags in the call setup mark the call as an eCall, and further indicate if the call was automatically or manually triggered. The call is routed to an eCall-capable PSAP, a voice channel is established between the vehicle and the PSAP, and an eCall in-band modem is used to carry a defined set of vehicle, sensor (e.g., crash related), and location data (the Minimum Set of Data or MSD) within the voice channel. The same in-band mechanism is used for the PSAP to acknowledge successful receipt of the MSD, and to request the vehicle to send a new MSD (e.g., to check if the state of or location of the vehicle or its occupants has changed). NG-eCall moves from circuit switched to all-IP, and carries the vehicle data and other eCall-specific data as additional data carried with the call. This document describes how IETF mechanisms for IP-based emergency calls, including [RFC6443] and [I-D.ietf-ecrit-additional-data] are used to provide the signaling and data exchange of the next generation of pan-European eCall.
The European Telecommunications Standards Institute (ETSI) [SDO-ETSI] has published a Technical Report titled "Mobile Standards Group (MSG); eCall for VoIP" [MSG_TR] that presents findings and recommendations regarding support for eCall in an all-IP environment. The recommendations include the use of 3GPP IMS emergency calling with additional elements identifying the call as an eCall and as carrying eCall data and with mechanisms for carrying the data and eCall-specific signaling. 3GPP IMS emergency services support multimedia, providing the ability to carry voice, text, and video. This capability is referred to within 3GPP as Multimedia Emergency Services (MMES).
A transition period will exist during which time the various entities involved in initiating and handling an eCall might support next-generation eCall, legacy eCall, or both. The issues of migration and co-existence during the transition period is outside the scope of this document.
eCall requirements are specified by CEN in [EN_16072] and by 3GPP in [TS22.101] clauses 10.7 and A.27. Requirements specific to vehicle data are contained in EN 15722 [msd].
Pan-European eCall provides a standardized and mandated set of vehicle related data, known as the Minimum Set of Data (MSD). The European Committee for Standardization (CEN) has specified this data in EN 15722 [msd], along with both ASN.1 and XML encodings for the MSD [msd]. Both circuit-switched eCall and this document use the ASN.1 PER encoding, which is specified in Annex A of EN 15722 [msd] (the XML encoding specified in Annex C is not used in this document).
The "Additional Data related to an Emergency Call" document [I-D.ietf-ecrit-additional-data] establishes a general mechanism for attaching blocks of data to a SIP emergency call. This document makes use of that mechanism to carry the eCall MSD in a SIP emergency call.
This document registers the 'application/emergencyCallData.eCall.MSD+per' MIME Content-Type to enable the MSD to be carried in SIP. As an ASN.1 PER encoded object, the data is binary and transported using binary content transfer encoding within SIP messages. This document also adds the 'eCall.MSD' entry to the Emergency Call Additional Data Blocks registry (established by [I-D.ietf-ecrit-additional-data]) to enable the MSD to be recognized as such in a SIP-based eCall emergency call.
Note that if additional data sets are defined and registered (e.g., in the future or in other regions) and transmitted using the same mechanisms, the size and frequency of transmission during a dialog need to be evaluated to be sure it is appropriate to use the signaling channel.
In circuit-switched eCall, the IVS places a special form of a 112 emergency call which carries an eCall flag (indicating that the call is an eCall and also if the call was manually or automatically triggered); the mobile network operator (MNO) recognizes the eCall flag and routes the call to an eCall-capable PSAP; vehicle data is transmitted to the PSAP via the eCall in-band modem (in the voice channel).
///----\\\ 112 voice call with eCall flag +------+ ||| IVS |||---------------------------------------->+ PSAP | \\\----/// vehicle data via eCall in-band modem +------+
Figure 1: circuit-switched eCall
An In-Vehicle System (IVS) initiating an NG-eCall transmits the MSD in accordance with [I-D.ietf-ecrit-additional-data] by encoding it as specified (per Annex A of EN 15722 [msd]) and attaching it to an INVITE as a MIME body part. The body part is identified by its MIME content-type ('application/emergencyCallData.eCall.MSD+per') in the Content-Type header field of the body part. The body part is assigned a unique identifier which is listed in a Content-ID header field in the body part. The INVITE is marked as containing the MSD by adding (or appending to) a Call-Info header field at the top level of the INVITE. This Call-Info header field contains a CID URL referencing the body part's unique identifier, and a 'purpose' parameter identifying the data as the eCall MSD per the registry entry; the 'purpose' parameter's value is 'emergencyCallData.' plus the root of the MIME type (not including the 'emergencyCallData.' prefix and any suffix such as '+per', so in this case, 'purpose=emergencyCallData.eCall.MSD'.
For NG-eCall, the IVS establishes an emergency call using a Request-URI indicating a manual or automatic eCall; the MNO (or ESInet) recognizes the eCall URN and routes the call to an NG-eCall capable PSAP; the PSAP interpets the vehicle data sent with the call and makes it available to the call taker.
///----\\\ IMS emergency call with eCall URN +------+
IVS ----------------------------------------->+ PSAP |
\\\----/// vehicle data included in call setup +------+
Figure 2: NG-eCall
This document registers new service URN children within the "sos" subservice. These URNs provide the mechanism by which an eCall is identified, and differentiate between manually and automatically triggered eCalls (which might be subject to different treatment, depending on policy). The two service URNs are: urn:service:sos.ecall.automatic and urn:service:sos.ecall.manual
The routing applied to eCalls might differ from those of other emergency calls, as eCalls are intended to be handled by PSAPs that support eCall. In regions without ESInets, typically the emergency services authorities and the originating network determine how such calls are routed. In a region that uses ESInets, the originating network passes all types of emergency calls to an ESInet (calls which have a request URI containing the "SOS" service URN). The ESInet is then responsible for routing such calls to the appropriate PSAP.
eCall requires the ability to place test calls. These are calls that are recognized and treated to some extent as eCalls but are not given emergency call treatment and are not handled by call takers. The specific handling of test eCalls is not itself standardized; typically, the test call facility allows the IVS or user to verify that an eCall can be successfully established with voice communication. The IVS might also be able to verify that the MSD was successfully received.
A service URN starting with "test." indicates a test call. For eCall, "urn:service:test.sos.ecall" indicates such a test feature. This functionality is defined in [RFC6881].
This document registers "urn:service:test.sos.ecall" for eCall test calls.
The CS-eCall test call facility is a non-emergency number so does not get treated as an emergency call. For NG-eCall, MNOs, emergency authorities, and PSAPs can determine how to treat a vehicle call requesting the "test" service URN so that the desired functionality is tested, but this is outside the scope of this document. (One possibility is that MNOs route such calls as non-emergency calls to a PSAP that supports NG-eCall; the PSAP accepts test calls, sends an MSD acknowledgment, and plays an audio clip (for example, saying that the call reached an eCall PSAP) in addition to supporting media loopback per [RFC6881]).
eCall requires the ability for the PSAP to acknowledge successful receipt of an MSD sent by the IVS, and for the PSAP to request that the IVS send an MSD (e.g., the call taker can initiate a request for a new MSD to see if there have been changes in the vehicle's state, e.g., location, direction, number of fastened seatbelts).
The mechanism established in [I-D.ietf-ecrit-additional-data], used in Section 5 of this document to carry the MSD from the IVS to the PSAP, is also used to carry a block of metadata/control data from the PSAP to the IVS. This eCall control block (sometimes referred to as eCall metadata) is an XML structure containing eCall-specific elements. When the PSAP needs to send an eCall control block that is in response to data sent by the IVS in a SIP request (e.g., the MSD in the initial INVITE), the control block can be sent in the SIP response to that request (e.g., the response to the INVITE request). When the PSAP needs to send an eCall control block in other circumstances (e.g., mid-call), the control block can be transmitted from the PSAP to the IVS in a SIP INFO request within the established dialog. The IVS sends the requested data (the MSD) in a new INFO request. This mechanism flexibly allows the PSAP to send eCall-specific data to the IVS and the IVS to respond.
This mechanism requires
When the IVS includes an unsolicited MSD in a SIP request (e.g., the initial INVITE), the PSAP sends a metadata/control block indicating successful/unsuccessful receipt of the MSD in the SIP response to the request. This also informs the IVS that an NG-eCall is in operation. If the IVS receives a SIP response without the metadata/control block, it indicates that the SIP dialog is not an NG-eCall. When the IVS sends a solicited MSD (e.g., in a SIP INFO request sent following receipt of a SIP INFO request containing a metadata/control block requesting an MSD), the PSAP does not send a metadata/control block indicating successful or unsuccessful receipt of the MSD. (Normal SIP retransmission handles non-receipt of requested data; if the IVS sends a requested MSD in an INFO request and does not receive a SIP status message for the INFO request, it resends it; if the PSAP requests an MSD and does not receive a SIP status message for the INFO request, it resends it.)
This provides flexibility to handle various circumstances. For example, if a PSAP is unable to accept an eCall (e.g., due to overload or too many calls from the same location), it can reject the INVITE. Since a metadata/control object is also included in the SIP response that rejects the call, the IVS knows if the PSAP received the MSD, and can inform the occupants that the PSAP successfully received the vehicle location and information but can't talk to the occupants at that time. Especially for SIP response codes that indicate an inability to conduct a call (as opposed to a technical inability to process the request), the IVS can also determine that the call was successful on a technical level (e.g., not necessary to retry as a CS-eCall). The SIP response code 600 (Busy Everywhere) can be used to indicate this. Other SIP response codes that can be interpreted in this way include 480 (Temporarily Unavailable), 486 (Busy Here), and 603 (Decline).
The eCall control block is an XML data structure allowing for acknowledgments and requests. It is carried in a SIP body part with a specific MIME content type. It can be extended via an IANA registry to add additional elements, attributes, and values. Two top-level elements are defined for use within an eCall control block:
Mandatory Actions (the IVS and the PSAP MUST support):
The <ack> element indicates the object being acknowledged (e.g., the MSD), and reports success or failure.
The <request> element contains attributes to indicate the request and to supply related information. The 'action' attribute is mandatory and indicates the specific action. An IANA registry is created in Section 14.8.1 to contain the allowed values.
Extensibility: New elements, child elements, attributes of new and existing elements, and values for new and existing attributes can be added in the IANA registry created in Section 14.8.2. The registry permits implementors to see what has been added, with a reference to the defining document. (Implementations are not expected to dynamically check the registry.) Implementations MUST ignore unsupported elements, attributes, and values.
The <ack> element is transmitted by the PSAP to acknowledge receipt of an eCall data object. An <ack> element sent by a PSAP references the unique ID of the data object that was sent by the IVS, and further indicates if the PSAP considers the receipt successful or not.
The <ack> element has the following attributes:
The <ack> element has the following attributes:
The <ack> element has no child elements
<?xml version="1.0" encoding="UTF-8"?>
<EmergencyCallData.eCall.Control
xmlns="urn:ietf:params:xml:ns:EmergencyCallData:eCall:control"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:EmergencyCallData:eCall:control">
<ack received="true" ref="1234567890@atlanta.example.com"/>
</EmergencyCallData.eCall.Control>
Figure 3: Ack Example from PSAP to IVS
A <request> element allows the PSAP to request that the IVS send an MSD. The following attributes are defined:
The <request> element has the following attributes:
<?xml version="1.0" encoding="UTF-8"?>
<EmergencyCallData.eCall.Control
xmlns="urn:ietf:params:xml:ns:EmergencyCallData:eCall:control"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:EmergencyCallData:eCall:control">
<request action="send-data" datatype="eCall.MSD"/>
</EmergencyCallData.eCall.Control>
Figure 4: Request Example
This document registers the 'emergencyCallData.eCall' INFO package.
Both endpoints (the IVS and the PSAP equipment) include 'emergencyCallData.eCall' in a Recv-Info header field per [RFC6086] to indicate ability to receive INFO messages carrying data as described here.
Support for the 'emergencyCallData.eCall' INFO package indicates the ability to receive body parts registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data].
An INFO request message carrying data related to an emergency call has an Info-Package header field set to 'emergencyCallData.eCall' per [RFC6086]. Per [I-D.ietf-ecrit-additional-data], the INFO request message contains one or more Call-Info header fields containing a CID URL referencing the unique identifier of a body part, and a 'purpose' parameter identifying the data. Because the data is being carried in an INFO request message, the body part also carries a Content-Disposition header field set to "Info-Package".
The requirements of Section 10 of [RFC6086] are addressed in the following sections.
This section describes "what type of information is carried in INFO requests associated with the Info Package, and for what types of applications and functionalities UAs can use the Info Package."
INFO requests associated with the emergencyCallData.eCall INFO package carry data associated with emergency calls as registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data]. The application is emergency calls established using SIP. The functionality is to carry data, metadata, and control information (requests) between vehicles and PSAPs. Refer to [TBD: THIS DOCUMENT] for more information.
This section describes "why the Info Package mechanism, rather than some other mechanism, has been chosen for the specific use-case...."
The use of INFO is based on an analysis of the requirements against the intent and effects of INFO versus other approaches (which included SIP MESSAGE, SIP OPTIONS, SIP re-INVITE, media plane transport, and non-SIP protocols). In particular, the transport of emergency call data blocks occurs within a SIP emergency dialog, using the mechanism established in [I-D.ietf-ecrit-additional-data], and is normally carried in the initial INVITE and its response; the use of INFO only occurs when emergency-call-related data needs to be sent mid-call. While MESSAGE could be used, it is not tied to a SIP dialog as is INFO and thus might not be associated with the dialog. SIP OPTIONS or re-INVITE could also be used, but is seen as less clean than INFO. SUBSCRIBE/NOTIFY could be coerced into service, but the semantics are not a good fit, e.g., the subscribe/notify mechanism provides one-way communication consisting of (often multiple) notifications from notifier to subscriber indicating that certain events in notifier have occurred, whereas what's needed here is two-way communication of data related to the emergency dialog. Use of the media plane mechanisms was discounted because the number of messages needing to be exchanged in a dialog is normally zero or very few, and the size of the data is likewise very small. The overhead caused by user plane setup (e.g., to use MSRP as transport) would be disproportionately large, and further, a high-level application protocol identifying the specific data block being sent within the media plane (as provided by the Call-Info header field parameters and MIME body part content type within INFO) would need to be defined.
Based on the the analyses, the SIP INFO method was chosen to provide for mid-call data transport.
The info package name is emergencyCallData.eCall.
None.
None.
Only those body parts registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data] are associated with this INFO package.
When more than one body part is included, they are enclosed in a multipart body part (e.g., multipart/mixed). When a body part is digitally signed or encrypted, it is enclosed in an appropriate body part (e.g., multipart/signed or multipart/encrypted).
The Content-Disposition value of a message body part associated with the emergencyCallData.eCall info package is "info-package".
None.
The rate of SIP INFO requests associated with the emergencyCallData.eCall info package is expected to be quite low (most dialogs are likely to contain zero INFO requests, while others can be expected to carry occasional requests).
The MIME content type registation for each data block registered in the 'Emergency Call Data Types' IANA registry established in [I-D.ietf-ecrit-additional-data] contains a discussion of the security and/or privacy considerations specific to that data block. The "Security Considerations" and "Privacy Considerations" sections of [TBD: THIS DOCUMENT] discuss security and privacy considerations of the data carried in eCealls.
See [TBD: THIS DOCUMENT] for protocol details.
See [TBD: THIS DOCUMENT] for protocol examples.
Figure 5 illustrates an eCall. The call uses the request URI 'urn:service:sos.ecall.automatic' service URN and is recognized as an eCall, and further as one that was invoked automatically by the IVS due to a crash or other serious incident. In this example, the originating network routes the call to an ESInet which routes the call to the appropriate NG-eCall capable PSAP. The emergency call is received by the ESInet's Emergency Services Routing Proxy (ESRP), as the entry point into the ESInet. The ESRP routes the call to a PSAP, where it is received by a call taker. In deployments where there is no ESInet, the originating network routes the call directly to the appropriate NG-eCall capable PSAP, an illustration of which would be identical to the one below except without an ESInet or ESRP.
+------------+ +---------------------------------------+
| | | +-------+ |
| | | | PSAP2 | |
| | | +-------+ |
| | | |
| | | +------+ +-------+ |
Vehicle-->| |--+->| ESRP |---->| PSAP1 |--> Call-Taker |
| | | +------+ +-------+ |
| | | |
| | | +-------+ |
| | | | PSAP3 | |
| Originating| | +-------+ |
| Mobile | | |
| Network | | ESInet |
+------------+ +---------------------------------------+
Figure 5: Example of NG-eCall Message Flow
The example, shown in Figure 6, illustrates a SIP eCall INVITE that contains an MSD. For simplicity, the example does not show all SIP headers, nor the SDP contents, nor does it show any additional data blocks added by the IVS or the originating mobile network. Because the MSD is encoded in ASN.1 PER, which is a binary encoding, its contents cannot be included in a text document.
INVITE urn:service:sos.ecall.automatic SIP/2.0
To: urn:service:sos.ecall.automatic
From: <sip:+13145551111@example.com>;tag=9fxced76sl
Call-ID: 3848276298220188511@atlanta.example.com
Geolocation: <cid:target123@example.com>
Geolocation-Routing: no
Call-Info: cid:1234567890@atlanta.example.com;
purpose=emergencyCallData.eCall.MSD;
cid:2345678901@atlanta.example.com;
purpose=emergencyCallData.eCall.control;
Accept: application/sdp, application/pidf+xml,
application/emergencyCallData.eCall.control+xml
CSeq: 31862 INVITE
Recv-Info: emergencyCallData.eCall
Allow: INVITE, ACK, PRACK, INFO, OPTIONS, CANCEL, REFER, BYE,
SUBSCRIBE, NOTIFY, UPDATE
Content-Type: multipart/mixed; boundary=boundary1
Content-Length: ...
--boundary1
Content-Type: application/sdp
...Session Description Protocol (SDP) goes here...
--boundary1
Content-Type: application/emergencyCallData.eCall.MSD+per
Content-ID: 1234567890@atlanta.example.com
Content-Disposition: by-reference;handling=optional
Content-Transfer-Encoding: binary
...MSD in ASN.1 PER encoding goes here...
--boundary1--
Figure 6: SIP NG-eCall INVITE
Continuing the example, Figure 7 illustrates a SIP 200 OK response to the INVITE of Figure 6, containing an eCall control block acknowledging successful receipt of the eCall MSD. (For simplicity, the example does not show all SIP headers.)
SIP/2.0 200 OK
To: <sip:+13145551111@example.com>;tag=9fxced76sl
From: Exemplar PSAP <urn:service:sos.ecall.automatic>
Call-ID: 3848276298220188511@atlanta.example.com
Call-Info: cid:2345678901@atlanta.example.com;
purpose=emergencyCallData.eCall.control;
Accept: application/sdp, application/pidf+xml,
application/emergencyCallData.eCall.control+xml,
application/emergencyCallData.eCall.MSD+per
CSeq: 31862 INVITE
Recv-Info: emergencyCallData.eCall
Allow: INVITE, ACK, PRACK, INFO, OPTIONS, CANCEL, REFER, BYE,
SUBSCRIBE, NOTIFY, UPDATE
Content-Type: multipart/mixed; boundary=boundaryX
Content-Length: ...
--boundaryX
Content-Type: application/sdp
...Session Description Protocol (SDP) goes here...
--boundaryX
Content-Type: application/EmergencyCallData.eCall.control+xml
Content-ID: 2345678901@atlanta.example.com
Content-Disposition: by-reference;handling=optional
<?xml version="1.0" encoding="UTF-8"?>
<EmergencyCallData.eCall.Control
xmlns="urn:ietf:params:xml:ns:EmergencyCallData:eCall:control"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"urn:ietf:params:xml:ns:EmergencyCallData:eCall:control">
<ack received="true" ref="1234567890@atlanta.example.com"/>
</EmergencyCallData.eCall.Control>
--boundaryX--
Figure 7: 200 OK response to INVITE
The security considerations described in [RFC5069] apply here.
In addition to any network-provided location (which might be determined solely by the network, or in cooperation with or possibly entirely by the originating device), an eCall carries an IVS-supplied location within the MSD. This is likely to be useful to the PSAP, especially when no network-provided location is included, or when the two locations are independently determined. Even in situations where the network-supplied location is limited to the cell site, this can be useful as a sanity check on the device-supplied location contained in the MSD.
The document [RFC7378] discusses trust issues regarding location provided by or determined in cooperation with end devices.
Security considerations specific to the mechanism by which the PSAP sends acknowledgments and requests to the vehicle are discussed in the "Security Considerations" block of Section 14.3.
Data received from external sources inherently carries implementation risks. For example, depending on the platform, buffer overflows can introduce remote code execution vulnerabilities, null characters can corrupt strings, numeric values used for internal calculations can result in underflow/overflow errors, malformed XML objects can expose parsing bugs, etc. Implementations need to be cognizant of the potential risks, observe best practices (which might include sufficiently capable static code analysis, fuzz testing, component isolation, avoiding use of unsafe coding techniques, third-party attack tests, signed software, over-the-air updates, etc.), and have multiple levels of protection. Implementors need to be aware that, potentially, the data objects described here and elsewhere might be malformed, might contain unexpected characters, excessively long attribute values, elements, etc.
Since this document depends on [I-D.ietf-ecrit-additional-data], the security considerations discussed there apply here (see especially the discussion of TLS, TLS versions, cypher suites, and PKI).
When vehicle data or control/metadata is contained in a signed or encrypted body part, the enclosing multipart (e.g., multipart/signed or multipart/encrypted) has the same Content-ID as the enclosed data part. This allows an entity to identify and access the data blocks it is interested in without having to dive deeply into the message structure or decrypt parts it is not interested in. (The 'purpose' parameter in a Call-Info header field identifies the data and contains a CID URL pointing to the data block in the body, which has a matching Content-ID body part header field).
Since this document builds on [I-D.ietf-ecrit-additional-data], the data structures specified there, and the corresponding privacy considerations discussed there, apply here as well. The MSD carries some additional identifying and personal information (mostly about the vehicle and less about the owner), as well as location information, and so needs to be protected against unauthorized disclosure. Local regulations may impose additional privacy protection requirements.
Privacy considerations specific to the data structure containing vehicle information are discussed in the "Security Considerations" block of Section 14.2.
Privacy considerations specific to the mechanism by which the PSAP sends acknowledgments and requests to the vehicle are discussed in the "Security Considerations" block of Section 14.3.
This section defines an XML schema for the eCall control block. The text description of the eCall control block in Section 8.1 is normative and supersedes any conflicting aspect of this schema.
<?xml version="1.0"?>
<xs:schema
targetNamespace=
"urn:ietf:params:xml:ns:EmergencyCallData:eCall:control"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:pi="urn:ietf:params:xml:ns:EmergencyCallData:eCall:control"
xmlns:xml="http://www.w3.org/XML/1998/namespace"
elementFormDefault="qualified"
attributeFormDefault="unqualified">
<xs:import namespace="http://www.w3.org/XML/1998/namespace"
schemaLocation="http://www.w3.org/2009/01/xml.xsd"/>
<xs:element name="EmergencyCallData.eCall.Control"
type="pi:eCallControlType"/>
<xs:simpleType name="iana-token">
<xs:annotation>
<xs:documentation>Permitted values specified in IANA
registries</xs:documentation>
</xs:annotation>
</xs:simpleType>
<xs:complexType name="eCallControlType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:choice>
<xs:element name="request" type="pi:requestType"/>
<xs:element name="ack" type="pi:ackType"/>
<xs:element type="cx:iana-token"/>
<xs:any namespace="##other" processContents="lax"
minOccurs="0"
maxOccurs="unbounded"/>
</xs:choice>
<xs:anyAttribute/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="ackType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:sequence minOccurs="1" maxOccurs="unbounded">
<xs:any namespace="##other" processContents="lax"
minOccurs="0"
maxOccurs="unbounded"/>
<xs:attribute type="cx:iana-token"/>
</xs:sequence>
<xs:attribute name="ref"
type="xs:anyURI"
use="required"/>
<xs:attribute name="received"
type="xs:boolean"/>
<xs:anyAttribute/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="requestType">
<xs:complexContent>
<xs:restriction base="xs:anyType">
<xs:choice minOccurs="1" maxOccurs="unbounded">
<xs:any namespace="##other" processContents="lax"
minOccurs="0"
maxOccurs="unbounded"/>
<xs:element type="cx:iana-token"/>
</xs:choice>
<xs:attribute name="action" type="xs:token" use="required"/>
<xs:attribute type="cx:iana-token" minOccurs="0"
maxOccurs="unbounded"/>
<xs:anyAttribute/>
</xs:restriction>
</xs:complexContent>
</xs:complexType>
</xs:schema>
Figure 8: eCall Control Block Schema
IANA is requested to register the URN 'urn:service:sos.ecall' under the sub-services 'sos' registry defined in Section 4.2 of [RFC5031].
This service requests resources associated with an emergency call placed by an in-vehicle system, carrying a standardized set of data related to the vehicle and incident. Two sub-services are registered as well:
IANA is also requested to register the URN 'urn:service:test.sos.ecall' under the sub-service 'test' registry defined in Setcion 17.2 of [RFC6881].
IANA is requested to add application/emergencyCallData.eCall.MSD+per as a MIME content type, with a reference to this document, in accordance to the procedures of RFC 6838 [RFC6838] and guidelines in RFC 7303 [RFC7303].
IANA is requested to add application/emergencyCallData.eCall.control+xml as a MIME content type, with a reference to this document, in accordance to the procedures of RFC 6838 [RFC6838] and guidelines in RFC 7303 [RFC7303].
This specification requests IANA to add the 'eCall.MSD' entry to the Emergency Call Additional Data Blocks registry (established by [I-D.ietf-ecrit-additional-data]), with a reference to this document.
This specification requests IANA to add the 'eCall.control' entry to the Emergency Call Additional Data Blocks registry (established by [I-D.ietf-ecrit-additional-data]), with a reference to this document.
IANA is requested to add emergencyCallData.eCall to the Info Packages Registry under "Session Initiation Protocol (SIP) Parameters", with a reference to this document.
This section registers a new XML namespace, as per the guidelines in RFC 3688 [RFC3688].
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Namespace for eCall Data</title>
</head>
<body>
<h1>Namespace for eCall Data</h1>
<p>See [TBD: This document].</p>
</body>
</html>
END
This section registers a new XML namespace, as per the guidelines in RFC 3688 [RFC3688].
BEGIN
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
"http://www.w3.org/TR/xhtml-basic/xhtml-basic10.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type"
content="text/html;charset=iso-8859-1"/>
<title>Namespace for eCall Data:
Control Block</title>
</head>
<body>
<h1>Namespace for eCall Data</h1>
<h2>Control Block</h2>
<p>See [TBD: This document].</p>
</body>
</html>
END
This document creates a new registry called 'eCall Control Data'. The following sub-registries are created for this registry.
This document creates a new sub-registry called "eCall Control Action Registry". As defined in [RFC5226], this registry operates under "Expert Review" rules. The expert should determine that the proposed action is within the purview of a vehicle, is sufficiently distinguishable from other actions, and the action is clearly and fully described. In most cases, a published and stable document is referenced for the description of the action.
The content of this registry includes:
The initial set of values is listed in Table 2.
| Name | Description |
|---|---|
| send-data | Section Section 8.1.2.1 of this document |
This document creates a new sub-registry called "eCall Control Extension Registry". This registry contains elements, attributes, and values for the eCall metadata/control object. As defined in [RFC5226], this registry operates under "Expert Review" rules. The expert should determine that the proposed elements, attributes, and/or values are within the purview of a vehicle, are sufficiently distinguishable, and clearly and fully described. In most cases, a published and stable document is referenced for the description of each element, attribute, or value. New values MUST indicate for which attributes or elements they are appropriate. New attributes MUST indicate in which elements they can appear and to which values that can be set. New elements MUST indicate if they can appear as child elements within other elements, and if so which elements, and/or if they can appear at the top level of an eCall metadata/control object. New elements MUST also describe which attributes and/or sub-elements they can contain and which are optional and which are mandatory. Note that this mechanism allows new items to be added while maintaining compatibility with existing implementations, since unrecognized items are ignored.
The content of this registry includes:
Brian Rosen was a co-author of the original document upon which this document is based.
We would like to thank Bob Williams and Ban Al-Bakri for their feedback and suggestion; Rex Buddenberg, Lena Chaponniere, Keith Drage, Stephen Edge, Wes George, Christer Holmberg, Ivo Sedlacek, and James Winterbottom for their review and comments; Robert Sparks and Paul Kyzivat for their help with the SIP mechanisms. We would like to thank Michael Montag, Arnoud van Wijk, Gunnar Hellstrom, and Ulrich Dietz for their help with the original document upon which this document is based.