draft-ietf-ecrit-local-emergency-rph-namespace-00.txt   draft-ietf-ecrit-local-emergency-rph-namespace-01.txt 
ECRIT Working Group James Polk ECRIT Working Group James Polk
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Intended Status: Standards Track (as PS) Oct 27, 2008 Expires: August 19, 2009 Feb 19, 2009
Expires: April 27, 2009 Intended Status: Standards Track (as PS)
Updates: RFC4412 (if published as an RFC)
IANA Registering a SIP Resource Priority Header IANA Registering a SIP Resource Priority Header
Namespace for Local Emergency Communications Namespace for Local Emergency Communications
draft-ietf-ecrit-local-emergency-rph-namespace-00 draft-ietf-ecrit-local-emergency-rph-namespace-01
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Abstract Abstract
This document creates and IANA registers the new Session Initiation This document creates and IANA registers the new Session Initiation
Protocol (SIP) Resource Priority header (RPH) namespace "esnet" for Protocol (SIP) Resource Priority header (RPH) namespace "esnet" for
local emergency usage to a public safety answering point (PSAP), local emergency usage to a public safety answering point (PSAP),
between PSAPs, and between a PSAP and first responders and their between PSAPs, and between a PSAP and first responders and their
organizations. organizations.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Rules of Usage of the Resource Priority Header . . . . . . . 3 2. Rules of Usage of the Resource Priority Header . . . . . . . 3
3. "esnet" Namespace Definition . . . . . . . . . . . . . . . . 5 3. "esnet" Namespace Definition . . . . . . . . . . . . . . . . 5
3.1 Namespace Definition Rules and Guidelines . . . . . . . . 6 3.1 Namespace Definition Rules and Guidelines . . . . . . . . 5
3.2 The "esnet" Namespace . . . . . . . . . . . . . . . . . . 6 3.2 The "esnet" Namespace . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4.1 IANA Resource-Priority Namespace Registration . . . . . . 7 4.1 IANA Resource-Priority Namespace Registration . . . . . . 6
4.2 IANA Priority-Value Registrations . . . . . . . . . . . . 7 4.2 IANA Priority-Value Registrations . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1 Normative References . . . . . . . . . . . . . . . . . . 7 7.1 Normative References . . . . . . . . . . . . . . . . . . 7
7.2 Informative References . . . . . . . . . . . . . . . . . 8 7.2 Informative References . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . 8 Author's Address . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . 8
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described "OPTIONAL" in this document are to be interpreted as described
in [RFC2119]. in [RFC2119].
1. Introduction 1. Introduction
This document creates and IANA registers the new Session Initiation This document creates and IANA registers the new Session Initiation
Protocol (SIP) Resource Priority header (RPH) namespace "esnet" for Protocol (SIP) Resource Priority header (RPH) namespace "esnet" for
local emergency usage. The SIP Resource-Priority header is defined local emergency usage. The SIP Resource-Priority header is defined
in RFC 4412 [RFC4412]. This new namespace can be from a caller in in RFC 4412 [RFC4412]. This new namespace within the public safety
distress, or added at the entry server into an emergency services answering point (PSAP) network ("ESInet"). This new namespace can
managed network, towards a public safety answering point (PSAP), be used for inbound calls to PSAPs, between PSAPs, and between a
i.e., the 911 or 112-based emergency services call taker. This PSAP and first responders and their organizations.
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 Within controlled environments, such as an IMS infrastructure or
Emergency Services network (ESINet), where misuse can be reduced to Emergency Services network (ESInet), where misuse can be reduced to
a minimum where possible, providing an explicit priority indication a minimum where possible, this namespace is to be to provide an
facilitates treatment of emergency SIP messages according to local explicit priority indication facilitates treatment of emergency SIP
policy. This indication is used to differentiate SIP signaling messages according to local policy. This indication is used to
requests, or dialogs, from other requests or dialogs. differentiate SIP requests, or dialogs, from other requests or
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 Usage of the "esnet" namespace is to be defined in a future
document(s). This document merely creates the namespace, per the document(s). This document merely creates the namespace, per the
rules within [RFC4412] necessitating a Standards Track RFC for rules within [RFC4412] necessitating a Standards Track RFC for
IANA registering new RPH namespaces and their relative IANA registering new RPH namespaces and their relative
priority-value order. [RFC4412] further states that modifying the priority-value order. [RFC4412] further states that modifying the
order or the number of priority-values to a registered namespace order or the number of priority-values to a registered namespace
SHOULD NOT occur, due to interoperability issues with dissimilar SHOULD NOT occur, due to interoperability issues with dissimilar
Implementations - perhaps separated by timing of each implementations.
implementation.
From this fact about RFC 4412, and the possibility that within From this fact about RFC 4412, and the possibility that within
emergency services networks, a Multilevel Precedence and Preemption emergency services networks, a Multilevel Precedence and Preemption
(MLPP)-like behavior can be achieved - ensuring more important calls (MLPP)-like behavior can be achieved - ensuring more important calls
are established or retained, the "esnet" namespace is given 5 are established or retained, the "esnet" namespace is given 5
priority-levels. MLPP-like SIP signaling is not defined in this priority-levels. MLPP-like SIP signaling is not defined in this
document for 911/112/999 style emergency calling, but it is not document for 911/112/999 style emergency calling, but it is not
prevented either. prevented either.
Within the ESINet, there will be emergency calls requiring different Within the ESINet, there will be emergency calls requiring different
treatments, according to the type of call. Does a citizen's call to 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 require the same, a higher or a lower relative priority than
a PSAP's call to a police department, or the police chief? What 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 about either relative to a call from within the ESINet to a
federal government's department of national security, such as the US federal government's department of national security, such as the US
Department of Homeland Security? For this reason, the "esnet" Department of Homeland Security? For this reason, the "esnet"
namespace is given multiple priority levels. namespace is given multiple priority levels.
This document does not define any of these behaviors, outside of This document does not define any of these behaviors, outside of
reminding the rules of RFC 4412 apply - though examples of usage are reminding readers that the rules of RFC 4412 apply - though examples
included for completeness. This document IANA registers the "esnet" of usage are included for completeness. This document IANA
RPH namespace for use within emergency services networks, not just registers the "esnet" RPH namespace for use within emergency
of those from citizens to PSAPs. services networks, not just of those from citizens to PSAPs.
2. Rules of Usage of the Resource Priority Header 2. Rules of Usage of the Resource Priority Header
This document updates the behaviors of the SIP Resource Priority This document updates the behaviors of the SIP Resource Priority
header, defined in [RFC4412], during the treatment options header, defined in [RFC4412], during the treatment options
surrounding this new "esnet" namespace only. The usage of the surrounding this new "esnet" namespace only. The usage of the
"esnet" namespace does not have a normal, or routine call level. "esnet" namespace does not have a normal, or routine call level.
Every use of this namespace will be in times of an emergency, where 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 at least one end of the signaling is with a local emergency
organization. organization.
skipping to change at page 4, line 8 skipping to change at page 4, line 8
Individual jurisdictions MAY configure their SIP entities for Individual jurisdictions MAY configure their SIP entities for
preemption treatment, but this is optional, and a local policy preemption treatment, but this is optional, and a local policy
decision. decision.
Conceivably, this could be an example of a generic network diagram Conceivably, this could be an example of a generic network diagram
where the "esnet" namespace is used: where the "esnet" namespace is used:
|<-"esnet" namespace->| |<-"esnet" namespace->|
| *WILL* be used | | *WILL* be used |
"esnet" namespace | ,-------. "esnet" namespace | ,-------.
can be used | ,' `. usage out of scope | ,' `.
|<------------>|<---"esnet" namespace ---->| / \ |<------------>|<---"esnet" namespace ---->| / \
+----+ | can be used +-----+ | ESINet | +----+ | can be used +-----+ | ESINet |
| UA |--- | --------------------|Proxy|-+ ------ | | UA |--- | --------------------|Proxy|-+ ------ |
+----+ \ | / +-----+ | | +----+ \ | / +-----+ | |
\ ,-------+ ,-------. | | +------+ | \ ,-------+ ,-------. | | +------+ |
+----+ ,' `. ,' `. | | |PSAP-1| | +----+ ,' `. ,' `. | | |PSAP-1| |
| UA |--- / User \ / Service \ | | +------+ | | UA |--- / User \ / Service \ | | +------+ |
+----+ ( Network +---+ Network )| | | +----+ ( Network +---+ Network )| | |
\ / \ / | | +------+ | \ / \ / | | +------+ |
+----+ /`. ,' `. .+-----+ | |PSAP-2| | +----+ /`. ,' `. .+-----+ | |PSAP-2| |
skipping to change at page 4, line 31 skipping to change at page 4, line 31
| | | | | | | |
+----+ | +-----+ | +------+ | +----+ | +-----+ | +------+ |
| UA |--- | --------------------|Proxy|-+ |PSAP-3| | | UA |--- | --------------------|Proxy|-+ |PSAP-3| |
+----+ \ | / +-----+ | +------+ | +----+ \ | / +-----+ | +------+ |
\ ,-------+ ,-------. | | | \ ,-------+ ,-------. | | |
+----+ ,' `. ,' `. | | | +----+ ,' `. ,' `. | | |
| UA |--- / User \ / Service \ | | +------+ | | UA |--- / User \ / Service \ | | +------+ |
+----+ ( Network +---+ Network )| | |PSAP-4| | +----+ ( Network +---+ Network )| | |PSAP-4| |
\ / \ / | | +------+ | \ / \ / | | +------+ |
+----+ /`. ,' `. .+-----+ | | +----+ /`. ,' `. .+-----+ | |
| UA |---- '-------' '-------' |Proxy|-+ *ANY* can | | UA |---- '-------' '-------' |Proxy|-+ ANY can |
+----+ | +-----+ | xfer a call | +----+ | +-----+ | xfer/call |
| | \ | | | / | | \ | | | /
`. | | | ,' `. | | | ,'
'-|-|-|-' '-|-|-|-'
| | | | | |
Police <--------------+ | | Police <--------------+ | |
Fire <----------+ | Fire <----------+ |
Federal Agency <-------+ Federal Agency <-------+
Figure 1: Where 'esnet' Namespace Can or Will be used Figure 1: Where 'esnet' Namespace Can or Will be used
In Figure 1., UAs connect to service providers that can have SIP In Figure 1., the "esnet" namespace is intended for usage within the
proxies. When calling for emergency help, the UAs MAY include a ESInet on the right side of the diagram. How it is utilized is out
"esnet" namespace in the SIP request. Use of this new namespace is of scope for this document. Adjacent VSPs to the ESInet MAY have a
OPTIONAL, and likely is not trustworthy, unless SIP signaling is trust relationship that includes allowing this neighboring VSP to
within a managed environment starting at the originating UAC. This use the "esnet" namespace to differentiate SIP requests and dialogs
namespace, therefore, MAY be overwritten or deleted, contrary to the within the VSP network. How this namespace is utilized is out of
rules of RFC 4412 [RFC4412]. These proxies in the service provider scope for this document. Because the more important usage of the
MAY either "esnet" namespace occurs within the ESInet, the edge proxy, called
an Emergency Services Routing Proxy (ESRP) can modify or delete this
o accept the existing RPH value with "esnet" in it, if one is namespace. This is a normative change to the allowed behavior within
present, and grant relative preferential treatment to the request [RFC4412], but MUST only be considered valid in this usage at the
when forwarding it to the ESINet. ESInet boundary for this one RP namespace (and associated
priority-value). The exact mapping between the sides of the ESRP at
o replace any existing RPH value, if one is present, and insert an the ESInet boundary are out of scope of this document.
"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 3. "esnet" Namespace Definition
One thing to keep in mind for now is the fact that this namespace 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 is not to be considered just "EMERGENCY" because there are a lot of
different kinds of emergencies, some on a military scale ([RFC4412] different kinds of emergencies, some on a military scale ([RFC4412]
defines 3 of these), some on a national scale ([RFC4412] defines 2 defines 3 of these), some on a national scale ([RFC4412] defines 2
of these), some on an international scale. These types of of these), some on an international scale. These types of
emergencies can also have their own namespaces, and although there emergencies can also have their own namespaces, and although there
are 5 defined for other uses, more are possible - so the 911/112/999 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 style of public user emergency calling for police or fire or
ambulance (etc) does not have a monopoly on the word "emergency". ambulance (etc) does not have a monopoly on the word "emergency".
Therefore the namespace "esnet" has been chosen, as it is most Therefore, the namespace "esnet" has been chosen, as it is most
recognizable as that of citizen calling for help from a public recognizable as that of citizen's call for help from a public
authority type of organization. This namespace will also be used authority type of organization. This namespace will also be used
for communications between emergency authorities, and MAY be used for communications between emergency authorities, and MAY be used
for emergency authorities calling public citizens. An example of for emergency authorities calling public citizens. An example of
the later is a PSAP operator calling back someone who previously the later is a PSAP operator calling back someone who previously
called 9111/112/999 and the communication was terminated before it called 9111/112/999 and the communication was terminated before it
should have been (in the operator's judgment). should have been (in the operator's judgment).
Here is an example of a Resource-Priority header using the esnet Here is an example of a Resource-Priority header using the esnet
namespace: namespace:
skipping to change at page 6, line 23 skipping to change at page 5, line 47
3.2. The "esnet" Namespace 3.2. The "esnet" Namespace
Per the rules of [RFC4412], each namespace has a finite set of Per the rules of [RFC4412], each namespace has a finite set of
relative priority-value(s), listed (below) from lowest priority to relative priority-value(s), listed (below) from lowest priority to
highest priority. In an attempt to not limit this namespace's use highest priority. In an attempt to not limit this namespace's use
in the future, more than one priority-value is assigned to the in the future, more than one priority-value is assigned to the
"esnet" namespace. This document does not RECOMMEND which "esnet" namespace. This document does not RECOMMEND which
priority-value is used where. That is for another document to priority-value is used where. That is for another document to
specify. This document does RECOMMEND the choice within a national specify. This document does RECOMMEND the choice within a national
jurisdiction is coordinated by all sub-jurisdictions to maintain jurisdiction be coordinated by all sub-jurisdictions to maintain
uniform SIP behavior throughout an emergency calling system. uniform SIP behavior throughout an emergency calling system.
The relative priority order for the "esnet" namespace is as follows: The relative priority order for the "esnet" namespace is as follows:
(lowest) esnet.0 (lowest) esnet.0
esnet.1 esnet.1
esnet.2 esnet.2
esnet.3 esnet.3
(highest) esnet.4 (highest) esnet.4
The "esnet" namespace will be assigned into the priority queuing The "esnet" namespace will be assigned into the priority queuing
algorithm (Section 4.5.2 of [RFC4412]) from the public user to the 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 PSAP. This does not limit its usage to only the priority queue
algorithm; meaning the preemption algorithm can be used where the algorithm; meaning the preemption algorithm can be used where the
local jurisdiction preferred to preempt normal calls in lieu of local jurisdiction preferred to preempt normal calls in lieu of
completing emergency calls. This document is not RECOMMENDING this completing emergency calls. This document is not RECOMMENDING this
usage, merely pointing out those behaviors is a matter of local usage, merely pointing out those behaviors are a matter of local
policy. policy.
NOTE: at this time, there has not been sufficient discussion about NOTE: at this time, there has not been sufficient discussion about
whether or not preemption will be used for communications between whether or not preemption will be used for communications between
PSAPs or between PSAPs and First responders (and their PSAPs or between PSAPs and First responders (and their
organizations). organizations).
4. IANA Considerations 4. IANA Considerations
4.1 IANA Resource-Priority Namespace Registration 4.1 IANA Resource-Priority Namespace Registration
skipping to change at page 7, line 31 skipping to change at page 6, line 44
sip-parameters section of IANA, the following (below) is to be added sip-parameters section of IANA, the following (below) is to be added
to the table: to the table:
Namespace: esnet Namespace: esnet
Reference: (this document) Reference: (this document)
Priority-Values (least to greatest): "0", "1","2", "3", "4" Priority-Values (least to greatest): "0", "1","2", "3", "4"
5. Security Considerations 5. Security Considerations
The Security considerations that apply to RFC 4412 [RFC4412] apply The Security considerations that apply to RFC 4412 [RFC4412] apply
here. This document introduces no new security issues relative to here.
RFC 4412.
That said, since this SIP header, used for emergency calling can The implications of using this header-value incorrectly can cause a
have a great impact on local communications, providers SHOULD use large impact on a network - given that this indication is to give
caution when deciding if they want to use a preemption algorithm preferential treatment of marked traffic great preference within the
within the public space for 911/112/999 type calling. As network than other traffic. This document does not indicate this
potentially already limited communications bandwidth might starve marking is intended for use by endpoints, yet protections need to be
out all other types of calls in a location. This decision might be taken to prevent granting preferential treatment to unauthorized
desired; but this effect might not be desired. 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 of calling is fairly local
in nature, with a finite number of URIs that are considered valid.
6. Acknowledgements 6. Acknowledgements
Thanks to Ken Carlberg, Janet Gunn, Fred Baker and Keith Drage for Thanks to Ken Carlberg, Janet Gunn, Fred Baker and Keith Drage for
help and encouragement with this effort. 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. References
7.1 Normative References 7.1 Normative References
[RFC2119] S. Bradner, "Key words for use in RFCs to Indicate [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate
[RFC4412] Schulzrinne, H., Polk, J., "Communications Resource [RFC4412] Schulzrinne, H., Polk, J., "Communications Resource
Priority for the Session Initiation Protocol (SIP)", RFC Priority for the Session Initiation Protocol (SIP)", RFC
7.2 Informative References 7.2 Informative References
skipping to change at page 8, line 20 skipping to change at line 340
Author's Address Author's Address
James Polk James Polk
3913 Treemont Circle 3913 Treemont Circle
Colleyville, Texas 76034 Colleyville, Texas 76034
USA USA
Phone: +1-817-271-3552 Phone: +1-817-271-3552
Email: jmpolk@cisco.com Email: jmpolk@cisco.com
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