ECRIT Working Group James Polk Internet-Draft Cisco Systems Expires: August 19, 2009 Feb 19, 2009 Intended Status: Standards Track (as PS)
Oct 27, 2008 Expires: April 27, 2009Updates: RFC4412 (if published as an RFC) IANA Registering a SIP Resource Priority Header Namespace for Local Emergency Communications draft-ietf-ecrit-local-emergency-rph-namespace-00draft-ietf-ecrit-local-emergency-rph-namespace-01 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or sheThis Internet-Draft is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed,submitted to IETF in accordancefull conformance with Section 6the provisions of BCP 78 and 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. 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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. 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 . . . . . . . . 65 3.2 The "esnet" Namespace . . . . . . . . . . . . . . . . . . 65 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 76 4.1 IANA Resource-Priority Namespace Registration . . . . . . 76 4.2 IANA Priority-Value Registrations . . . . . . . . . . . . 76 5. Security Considerations . . . . . . . . . . . . . . . . . . . 76 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 . . . . . . . 8The 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 atwithin the entry server into an emergency services managed network, towards apublic safety answering point (PSAP), i.e., the 911 or 112-based emergency services call taker.(PSAP) network ("ESInet"). This new namespace can be used for inbound calls to PSAPs, 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),(ESInet), where misuse can be reduced to a minimum where possible, providingthis namespace is to be to provide an explicit priority indication facilitates treatment of emergency SIP messages according to local policy. This indication is used to differentiate SIP signalingrequests, or dialogs, from other requests or dialogs.dialogs that do not have the need for priority treatment. It can also be imagined that Voice Service Providers (VSP) directly attached to an ESInet can have a trust relationship with the ESInet such that within these networks, SIP requests (thereby the session they establish) make use of this "esnet" namespace for appropriate treatment. 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 implementation.implementations. 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 readers that 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: |<-"esnet" namespace->| | *WILL* be used | "esnet" namespace | ,-------. can be usedusage out of scope | ,' `. |<------------>|<---"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*ANY can | +----+ | +-----+ | xfer a callxfer/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 signalingis intended for usage within a managed environment starting atthe originating UAC. This namespace, therefore, MAY be overwritten or deleted, contrary toESInet on the rulesright side of RFC 4412 [RFC4412]. These proxies in the service provider MAY either o acceptthe existing RPH value with "esnet" in it, if onediagram. How it is present, and grant relative preferential treatmentutilized is out of scope for this document. Adjacent VSPs to the request when forwarding itESInet MAY have a trust relationship that includes allowing this neighboring VSP to use the ESINet. o replace any existing RPH value, if one is present, and insert an"esnet" namespace and give relative preferential treatmentto 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 thedifferentiate SIP request towards the ESINet. Adjacent service providers can have a trust relationship in regards to emergency calling,requests and dialogs within the receiving service provider can accept the inbound 'esnet' RPHVSP network. How this 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 typeis utilized is out of request it is, in addition toscope for this document. Because the naturemore important usage of the request. If the request is destined for a PSAP, according to"esnet" namespace occurs within the receiving SP, it MAY treatESInet, the request as if it were coming directly fromedge proxy, called an Emergency Services Routing Proxy (ESRP) can modify or delete this namespace. This is a UA, and act accordingnormative change 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 areallowed behavior within [RFC4412], but MUST only be considered valid in this usage at the message, and what treatments the message has received, the ESINet edge proxy will ensure there is an RPH with the "esnet"ESInet boundary for this one RP namespace in(and associated priority-value). The exact mapping between the request. Local policy will dictatesides of the priority-value to be assigned withinESRP at the ESINet. This document makes no recommendations.ESInet boundary are out of scope of this document. 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". ThereforeTherefore, the namespace "esnet" has been chosen, as it is most recognizable as that of citizen callingcitizen's call 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: 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 isbe 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 isare 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). 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, sinceThe implications of using this SIP header, used for emergency callingheader-value incorrectly can havecause a greatlarge impact on local communications, providers SHOULD use caution when deciding if they want to usea preemption algorithmnetwork - given that this indication is to give preferential treatment of marked traffic great preference within the public spacenetwork than other traffic. This document does not indicate this marking is intended for use by endpoints, yet protections need to be taken to prevent granting preferential treatment to unauthorized users not calling for emergency help. A simple means of preventing this usage is to not allow marked traffic preferential treatment unless the destination is towards the local/regional ESInet. 911/112/999 type calling. As potentially already limited communications bandwidth might starve out all other typesof callscalling is fairly local in nature, with a location. This decision might be desired; but this effect might not be desired.finite number of URIs that are considered valid. 6. Acknowledgements Thanks to Ken Carlberg, Janet Gunn, Fred Baker and Keith Drage for help and encouragement with this effort. Thanks to Henning Schulzrinne, Ted Hardie, Hannes Tschofenig, Brian Rosen and Marc Linsner for constructive comments. 7. References 7.1 Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate [RFC4412] Schulzrinne, H., Polk, J., "Communications Resource Priority for the Session Initiation Protocol (SIP)", RFC 7.2 Informative References none Author's Address James Polk 3913 Treemont Circle Colleyville, Texas 76034 USA Phone: +1-817-271-3552 Email: email@example.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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