ECRIT Working Group James Polk Internet-Draft Cisco Systems Intended Status: Standards Track (as PS) Oct 27, 2008 Expires: April 27, 2009 IANA Registering a SIP Resource Priority Header Namespace for Local Emergency Communications draft-ietf-ecrit-local-emergency-rph-namespace-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 27, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Abstract This document creates and IANA registers the new Session Initiation Protocol (SIP) Resource Priority header (RPH) namespace "esnet" for local emergency usage to a public safety answering point (PSAP), between PSAPs, and between a PSAP and first responders and their organizations. Polk Expires April 27, 2009 [Page 1] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Rules of Usage of the Resource Priority Header . . . . . . . 3 3. "esnet" Namespace Definition . . . . . . . . . . . . . . . . 5 3.1 Namespace Definition Rules and Guidelines . . . . . . . . 6 3.2 The "esnet" Namespace . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 4.1 IANA Resource-Priority Namespace Registration . . . . . . 7 4.2 IANA Priority-Value Registrations . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1 Normative References . . . . . . . . . . . . . . . . . . 7 7.2 Informative References . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . 8 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]. 1. Introduction This document creates and IANA registers the new Session Initiation Protocol (SIP) Resource Priority header (RPH) namespace "esnet" for local emergency usage. The SIP Resource-Priority header is defined in RFC 4412 [RFC4412]. This new namespace can be from a caller in distress, or added at the entry server into an emergency services managed network, towards a public safety answering point (PSAP), i.e., the 911 or 112-based emergency services call taker. This new namespace can be used between PSAPs, and between a PSAP and first responders and their organizations. Within controlled environments, such as an IMS infrastructure or Emergency Services network (ESINet), where misuse can be reduced to a minimum where possible, providing an explicit priority indication facilitates treatment of emergency SIP messages according to local policy. This indication is used to differentiate SIP signaling requests, or dialogs, from other requests or dialogs. Usage of the "esnet" namespace is to be defined in a future document(s). This document merely creates the namespace, per the rules within [RFC4412] necessitating a Standards Track RFC for IANA registering new RPH namespaces and their relative priority-value order. [RFC4412] further states that modifying the order or the number of priority-values to a registered namespace SHOULD NOT occur, due to interoperability issues with dissimilar Implementations - perhaps separated by timing of each Polk Expires April 27, 2009 [Page 2] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 implementation. From this fact about RFC 4412, and the possibility that within emergency services networks, a Multilevel Precedence and Preemption (MLPP)-like behavior can be achieved - ensuring more important calls are established or retained, the "esnet" namespace is given 5 priority-levels. MLPP-like SIP signaling is not defined in this document for 911/112/999 style emergency calling, but it is not prevented either. Within the ESINet, there will be emergency calls requiring different treatments, according to the type of call. Does a citizen's call to a PSAP require the same, a higher or a lower relative priority than a PSAP's call to a police department, or the police chief? What about either - relative to a call from within the ESINet to a federal government's department of national security, such as the US Department of Homeland Security? For this reason, the "esnet" namespace is given multiple priority levels. This document does not define any of these behaviors, outside of reminding the rules of RFC 4412 apply - though examples of usage are included for completeness. This document IANA registers the "esnet" RPH namespace for use within emergency services networks, not just of those from citizens to PSAPs. 2. Rules of Usage of the Resource Priority Header This document updates the behaviors of the SIP Resource Priority header, defined in [RFC4412], during the treatment options surrounding this new "esnet" namespace only. The usage of the "esnet" namespace does not have a normal, or routine call level. Every use of this namespace will be in times of an emergency, where at least one end of the signaling is with a local emergency organization. The "esnet" namespace has 5 priority-values, in a specified relative priority order, and is a queue-based treatment namespace [RFC4412]. Individual jurisdictions MAY configure their SIP entities for preemption treatment, but this is optional, and a local policy decision. Conceivably, this could be an example of a generic network diagram where the "esnet" namespace is used: Polk Expires April 27, 2009 [Page 3] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 |<-"esnet" namespace->| | *WILL* be used | "esnet" namespace | ,-------. can be used | ,' `. |<------------>|<---"esnet" namespace ---->| / \ +----+ | can be used +-----+ | ESINet | | UA |--- | --------------------|Proxy|-+ ------ | +----+ \ | / +-----+ | | \ ,-------+ ,-------. | | +------+ | +----+ ,' `. ,' `. | | |PSAP-1| | | UA |--- / User \ / Service \ | | +------+ | +----+ ( Network +---+ Network )| | | \ / \ / | | +------+ | +----+ /`. ,' `. .+-----+ | |PSAP-2| | | UA |---- '-------' '-------' |Proxy|-+ +------+ | +----+ | +-----+ | | | | | | +----+ | +-----+ | +------+ | | UA |--- | --------------------|Proxy|-+ |PSAP-3| | +----+ \ | / +-----+ | +------+ | \ ,-------+ ,-------. | | | +----+ ,' `. ,' `. | | | | UA |--- / User \ / Service \ | | +------+ | +----+ ( Network +---+ Network )| | |PSAP-4| | \ / \ / | | +------+ | +----+ /`. ,' `. .+-----+ | | | UA |---- '-------' '-------' |Proxy|-+ *ANY* can | +----+ | +-----+ | xfer a call | | | \ | | | / `. | | | ,' '-|-|-|-' | | | Police <--------------+ | | Fire <----------+ | Federal Agency <-------+ Figure 1: Where 'esnet' Namespace Can or Will be used In Figure 1., UAs connect to service providers that can have SIP proxies. When calling for emergency help, the UAs MAY include a "esnet" namespace in the SIP request. Use of this new namespace is OPTIONAL, and likely is not trustworthy, unless SIP signaling is within a managed environment starting at the originating UAC. This namespace, therefore, MAY be overwritten or deleted, contrary to the rules of RFC 4412 [RFC4412]. These proxies in the service provider MAY either o accept the existing RPH value with "esnet" in it, if one is present, and grant relative preferential treatment to the request when forwarding it to the ESINet. o replace any existing RPH value, if one is present, and insert an Polk Expires April 27, 2009 [Page 4] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 "esnet" namespace and give relative preferential treatment to the request when forwarding it to the ESINet. o insert an "esnet" namespace in a new RPH and give relative preferential treatment to the request when forwarding the SIP request towards the ESINet. Adjacent service providers can have a trust relationship in regards to emergency calling, and the receiving service provider can accept the inbound 'esnet' RPH namespace value and give preferential treatment to the request when forwarding it to the ESINet. On the other hand, SPs can choose to process each inbound SIP requests with its own policies, based on the type of request it is, in addition to the nature of the request. If the request is destined for a PSAP, according to the receiving SP, it MAY treat the request as if it were coming directly from a UA, and act according to the 3 bullets above. Ultimately, the edge proxy at the ESINet will receive emergency SIP request, and process the request according to its rules. Regardless of what RPH indications there are in the message, and what treatments the message has received, the ESINet edge proxy will ensure there is an RPH with the "esnet" namespace in the request. Local policy will dictate the priority-value to be assigned within the ESINet. This document makes no recommendations. 3. "esnet" Namespace Definition One thing to keep in mind for now is the fact that this namespace is not to be considered just "EMERGENCY" because there are a lot of different kinds of emergencies, some on a military scale ([RFC4412] defines 3 of these), some on a national scale ([RFC4412] defines 2 of these), some on an international scale. These types of emergencies can also have their own namespaces, and although there are 5 defined for other uses, more are possible - so the 911/112/999 style of public user emergency calling for police or fire or ambulance (etc) does not have a monopoly on the word "emergency". Therefore the namespace "esnet" has been chosen, as it is most recognizable as that of citizen calling for help from a public authority type of organization. This namespace will also be used for communications between emergency authorities, and MAY be used for emergency authorities calling public citizens. An example of the later is a PSAP operator calling back someone who previously called 9111/112/999 and the communication was terminated before it should have been (in the operator's judgment). Here is an example of a Resource-Priority header using the esnet namespace: Polk Expires April 27, 2009 [Page 5] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 Resource-Priority: esnet.0 3.1. Namespace Definition Rules and Guidelines This specification defines one unique namespace for emergency calling scenarios, "esnet", constituting its registration with IANA. This IANA registration contains the facets defined in Section 9 of [RFC4412]. 3.2. The "esnet" Namespace Per the rules of [RFC4412], each namespace has a finite set of relative priority-value(s), listed (below) from lowest priority to highest priority. In an attempt to not limit this namespace's use in the future, more than one priority-value is assigned to the "esnet" namespace. This document does not RECOMMEND which priority-value is used where. That is for another document to specify. This document does RECOMMEND the choice within a national jurisdiction is coordinated by all sub-jurisdictions to maintain uniform SIP behavior throughout an emergency calling system. The relative priority order for the "esnet" namespace is as follows: (lowest) esnet.0 esnet.1 esnet.2 esnet.3 (highest) esnet.4 The "esnet" namespace will be assigned into the priority queuing algorithm (Section 4.5.2 of [RFC4412]) from the public user to the PSAP. This does not limit its usage to only the priority queue algorithm; meaning the preemption algorithm can be used where the local jurisdiction preferred to preempt normal calls in lieu of completing emergency calls. This document is not RECOMMENDING this usage, merely pointing out those behaviors is a matter of local policy. NOTE: at this time, there has not been sufficient discussion about whether or not preemption will be used for communications between PSAPs or between PSAPs and First responders (and their organizations). Polk Expires April 27, 2009 [Page 6] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 4. IANA Considerations 4.1 IANA Resource-Priority Namespace Registration Within the "Resource-Priority Namespaces" of the sip-parameters section of IANA (created by [RFC4412]), the following entries will be added to this table: Intended New warn- New resp. Namespace Levels Algorithm code code Reference --------- ------ -------------- --------- --------- --------- esnet 5 queue no no [This doc] 4.2 IANA Priority-Value Registrations Within the Resource-Priority Priority-values registry of the sip-parameters section of IANA, the following (below) is to be added to the table: Namespace: esnet Reference: (this document) Priority-Values (least to greatest): "0", "1","2", "3", "4" 5. Security Considerations The Security considerations that apply to RFC 4412 [RFC4412] apply here. This document introduces no new security issues relative to RFC 4412. That said, since this SIP header, used for emergency calling can have a great impact on local communications, providers SHOULD use caution when deciding if they want to use a preemption algorithm within the public space for 911/112/999 type calling. As potentially already limited communications bandwidth might starve out all other types of calls in a location. This decision might be desired; but this effect might not be desired. 6. Acknowledgements Thanks to Ken Carlberg, Janet Gunn, Fred Baker and Keith Drage for help and encouragement with this effort. 7. References 7.1 Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997 Polk Expires April 27, 2009 [Page 7] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 [RFC4412] Schulzrinne, H., Polk, J., "Communications Resource Priority for the Session Initiation Protocol (SIP)", RFC 4411, Feb 2006 7.2 Informative References none Author's Address James Polk 3913 Treemont Circle Colleyville, Texas 76034 USA Phone: +1-817-271-3552 Email: jmpolk@cisco.com Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an Polk Expires April 27, 2009 [Page 8] Internet-Draft SIP RPH Namespace for Local Emergencies Oct 2008 attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Polk Expires April 27, 2009 [Page 9]