draft-ietf-sipcore-event-rate-control-09.txt   rfc6446.txt 
Network Working Group A. Niemi Internet Engineering Task Force (IETF) A. Niemi
Internet-Draft K. Kiss Request for Comments: 6446 K. Kiss
Updates: 3265 (if approved) Nokia Updates: 3265 Nokia
Intended status: Standards Track S. Loreto Category: Standards Track S. Loreto
Expires: March 3, 2012 Ericsson ISSN: 2070-1721 Ericsson
August 31, 2011 January 2012
Session Initiation Protocol (SIP) Event Notification Extension for Session Initiation Protocol (SIP) Event Notification Extension
Notification Rate Control for Notification Rate Control
draft-ietf-sipcore-event-rate-control-09
Abstract Abstract
This document specifies mechanisms for adjusting the rate of Session This document specifies mechanisms for adjusting the rate of Session
Initiation Protocol (SIP) event notifications. These mechanisms can Initiation Protocol (SIP) event notifications. These mechanisms can
be applied in subscriptions to all SIP event packages. This document be applied in subscriptions to all SIP event packages. This document
updates RFC 3265. updates RFC 3265.
Status of this Memo Status of This Memo
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 This is an Internet Standards Track document.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on March 3, 2012. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6446.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 3, line 21 skipping to change at page 3, line 21
3.2. Use Case for Setting a Minimum Rate for Notifications . . 6 3.2. Use Case for Setting a Minimum Rate for Notifications . . 6
3.3. Use Case for Specifying an Adaptive Minimum Rate of 3.3. Use Case for Specifying an Adaptive Minimum Rate of
Notifications . . . . . . . . . . . . . . . . . . . . . . 6 Notifications . . . . . . . . . . . . . . . . . . . . . . 6
3.4. Requirements . . . . . . . . . . . . . . . . . . . . . . . 7 3.4. Requirements . . . . . . . . . . . . . . . . . . . . . . . 7
4. Basic Operations . . . . . . . . . . . . . . . . . . . . . . . 8 4. Basic Operations . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 8 4.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 8
4.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 9 4.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 9
5. Operation of the Maximum Rate Mechanism . . . . . . . . . . . 9 5. Operation of the Maximum Rate Mechanism . . . . . . . . . . . 9
5.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 9 5.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 9
5.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 10 5.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 10
5.3. Selecting the Maximum Rate . . . . . . . . . . . . . . . . 10 5.3. Selecting the Maximum Rate . . . . . . . . . . . . . . . . 11
5.4. The Maximum Rate Mechanism for Resource List Server . . . 11 5.4. The Maximum Rate Mechanism for the Resource List Server . 11
5.5. Buffer Policy Description . . . . . . . . . . . . . . . . 13 5.5. Buffer Policy Description . . . . . . . . . . . . . . . . 13
5.5.1. Partial State Notifications . . . . . . . . . . . . . 13 5.5.1. Partial-State Notifications . . . . . . . . . . . . . 13
5.5.2. Full State Notifications . . . . . . . . . . . . . . . 13 5.5.2. Full-State Notifications . . . . . . . . . . . . . . . 13
5.6. Estimated Bandwidth Savings . . . . . . . . . . . . . . . 14 5.6. Estimated Bandwidth Savings . . . . . . . . . . . . . . . 14
6. Operation of the Minimum Rate Mechanism . . . . . . . . . . . 14 6. Operation of the Minimum Rate Mechanism . . . . . . . . . . . 14
6.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 14 6.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 14
6.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 15 6.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 15
6.3. Selecting the Minimum Rate . . . . . . . . . . . . . . . . 15 6.3. Selecting the Minimum Rate . . . . . . . . . . . . . . . . 16
7. Operation of the Adaptive Minimum Rate Mechanism . . . . . . . 16 7. Operation of the Adaptive Minimum Rate Mechanism . . . . . . . 16
7.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 16 7.1. Subscriber Behavior . . . . . . . . . . . . . . . . . . . 16
7.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 16 7.2. Notifier Behavior . . . . . . . . . . . . . . . . . . . . 17
7.3. Selecting the Adaptive Minimum Rate . . . . . . . . . . . 18 7.3. Selecting the Adaptive Minimum Rate . . . . . . . . . . . 18
7.4. Calculating the Timeout . . . . . . . . . . . . . . . . . 18 7.4. Calculating the Timeout . . . . . . . . . . . . . . . . . 18
8. Usage of the Maximum Rate, Minimum Rate and Adaptive 8. Usage of the Maximum Rate, Minimum Rate, and Adaptive
Minimum Rate Mechanisms in a combination . . . . . . . . . . . 19 Minimum Rate Mechanisms in a Combination . . . . . . . . . . . 19
9. Protocol Element Definitions . . . . . . . . . . . . . . . . . 20 9. Protocol Element Definitions . . . . . . . . . . . . . . . . . 20
9.1. "max-rate", "min-rate" and "adaptive-min-rate" Header 9.1. "max-rate", "min-rate", and "adaptive-min-rate" Header
Field Parameters . . . . . . . . . . . . . . . . . . . . . 20 Field Parameters . . . . . . . . . . . . . . . . . . . . . 21
9.2. Grammar . . . . . . . . . . . . . . . . . . . . . . . . . 21 9.2. Grammar . . . . . . . . . . . . . . . . . . . . . . . . . 21
9.3. Event Header Field Usage in Responses to the NOTIFY 9.3. Event Header Field Usage in Responses to the NOTIFY
request . . . . . . . . . . . . . . . . . . . . . . . . . 21 Request . . . . . . . . . . . . . . . . . . . . . . . . . 21
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
11. Security Considerations . . . . . . . . . . . . . . . . . . . 22 11. Security Considerations . . . . . . . . . . . . . . . . . . . 22
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 23
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23
13.1. Normative References . . . . . . . . . . . . . . . . . . . 23 13.1. Normative References . . . . . . . . . . . . . . . . . . . 23
13.2. Informative References . . . . . . . . . . . . . . . . . . 24 13.2. Informative References . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
The SIP events framework [RFC3265] defines a generic framework for The SIP events framework [RFC3265] defines a generic framework for
subscriptions to and notifications of events related to SIP systems. subscriptions to and notifications of events related to SIP systems.
This framework defines the methods SUBSCRIBE and NOTIFY, and This framework defines the methods SUBSCRIBE and NOTIFY, and
introduces the concept of an event package, which is a concrete introduces the concept of an event package, which is a concrete
application of the SIP events framework to a particular class of application of the SIP events framework to a particular class of
events. events.
One of the things the SIP events framework mandates is that each One of the things the SIP events framework mandates is that each
event package specification defines an absolute maximum on the rate event package specification defines an absolute maximum on the rate
at which notifications are allowed to be generated by a single at which notifications are allowed to be generated by a single
notifier. Such a limit is provided in order to reduce network load. notifier. Such a limit is provided in order to reduce network load.
All of the existing event package specifications include a maximum All of the existing event package specifications include a
notification rate recommendation, ranging from once in every five recommendation for the maximum notification rate, ranging from once
seconds [RFC3856], [RFC3680], [RFC3857] to once per second [RFC3842]. in every five seconds [RFC3856], [RFC3680], [RFC3857] to once per
second [RFC3842].
Per the SIP events framework, each event package specification is Per the SIP events framework, each event package specification is
also allowed to define additional throttle mechanisms which allow the allowed to define additional throttle mechanisms that allow the
subscriber to further limit the rate of event notification. So far subscriber to further limit the rate of event notification. So far,
none of the event package specifications have defined such a none of the event package specifications have defined such a
mechanism. mechanism.
The resource list extension [RFC4662] to the SIP events framework The resource list extension [RFC4662] to the SIP events framework
also deals with rate limiting of event notifications. The extension also deals with rate limiting of event notifications. The extension
allows a subscriber to subscribe to a heterogeneous list of resources allows a subscriber to subscribe to a heterogeneous list of resources
with a single SUBSCRIBE request, rather than having to install a with a single SUBSCRIBE request, rather than having to install a
subscription for each resource separately. The event list subscription for each resource separately. The event list
subscription also allows rate limiting, or throttling of subscription also allows rate limiting, or throttling of
notifications, by means of the Resource List Server (RLS) buffering notifications, by means of the Resource List Server (RLS) buffering
notifications of resource state changes, and sending them in batches. notifications of resource state changes, and sending them in batches.
However, the event list mechanism provides no means for the However, the event list mechanism provides no means for the
subscriber to set the interval for the throttling. subscriber to set the interval for the throttling.
Some event packages are also interested in specifying an absolute or Some event packages are also interested in specifying an absolute or
an adaptive minimum rate at which notifications need to be generated an adaptive minimum rate at which notifications need to be generated
by a notifier. This helps the subscriber to effectively use by a notifier. This helps the subscriber to effectively use
different trigger criterias within a subscription to eliminate different trigger criteria within a subscription to eliminate
unnecessary notifications but at the same time make sure that the unnecessary notifications but at the same time make sure that the
current event state is periodically received. current event state is periodically received.
This document defines an extension to the SIP events framework This document defines an extension to the SIP events framework by
defining the following three Event header field parameters that allow defining the following three Event header field parameters that allow
a subscriber to set a maximum, a minimum and an adaptive minimum rate a subscriber to set a maximum, a minimum, and an adaptive minimum
of notifications generated by the notifier: rate of notifications generated by the notifier:
max-rate: specifies a maximum number of notifications per second. max-rate: specifies a maximum number of notifications per second.
min-rate: specifies a minimum number of notifications per second. min-rate: specifies a minimum number of notifications per second.
adaptive-minimum-rate: specifies an adaptive minimum number of adaptive-min-rate: specifies an adaptive minimum number of
notifications per second. notifications per second.
These mechanisms are applicable to any event subscription, both These mechanisms are applicable to any event subscription, both
single event subscription and event list subscription. A notifier single event subscription and event list subscription. A notifier
compliant to this specification will adjust the rate at which it compliant to this specification will adjust the rate at which it
generates notifications. generates notifications.
2. Definitions and Document Conventions 2. Definitions and Document Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
skipping to change at page 5, line 34 skipping to change at page 5, line 34
Indented passages such as this one are used in this document to Indented passages such as this one are used in this document to
provide additional information and clarifying text. They do not provide additional information and clarifying text. They do not
contain normative protocol behavior. contain normative protocol behavior.
3. Overview 3. Overview
3.1. Use Case for Limiting the Maximum Rate of Notifications 3.1. Use Case for Limiting the Maximum Rate of Notifications
A presence client in a mobile device contains a list of 100 buddies A presence client in a mobile device contains a list of 100 buddies
or presentities. In order to decrease the processing and network or presentities. In order to decrease the processing and network
load of watching 100 presentities, the presence client has employed a load of watching 100 presentities, the presence client has employed
Resource List Server (RLS) with the list of buddies, and therefore an RLS with the list of buddies, and therefore only needs a single
only needs a single subscription to the RLS in order to receive subscription to the RLS to receive notifications of the presence
notifications of the presence state of the resource list. state of the resource list.
In order to control the buffer policy of the RLS, the presence client In order to control the buffer policy of the RLS, the presence client
sets a maximum rate of notifications. The RLS will buffer sets a maximum rate of notifications. The RLS will buffer
notifications that are generated faster than they are allowed to be notifications that are generated faster than they are allowed to be
sent due to the maximum rate and batch all of the buffered state sent due to the maximum rate and batch all of the buffered state
changes together in a single notification. The maximum rate applies changes together in a single notification. The maximum rate applies
to the overall resource list, which means that there is a hard cap to the overall resource list, which means that there is a hard cap
imposed by the maximum rate to the number of notifications per second imposed by the maximum rate to the number of notifications per second
the presence client can expect to receive. that the presence client can expect to receive.
The presence client can also modify the maximum rate of notifications The presence client can also modify the maximum rate of notifications
during the lifetime of the subscription. For example, if the mobile during the lifetime of the subscription. For example, if the mobile
device detects inactivity from the user for a period of time, the device detects inactivity from the user for a period of time, the
presence client can simply pause notifications by choosing a "max- presence client can simply pause notifications by choosing a "max-
rate" parameter that allows only a single notification for the rate" parameter that allows only a single notification for the
remainder of the subscription lifetime. When the user becomes active remainder of the subscription lifetime. When the user becomes active
again, the presence client can resume the stream of notifications by again, the presence client can resume the stream of notifications by
re-subscribing with a "max-rate" parameter set to the earlier used re-subscribing with a "max-rate" parameter set to the earlier-used
value. Application of the mechanism defined by RFC 5839 [RFC5839] value. Application of the mechanism defined by RFC 5839 [RFC5839]
can also eliminate the transmission of a (full-state) notification can also eliminate the transmission of a (full-state) notification
carrying the latest resource state to the presence client after a carrying the latest resource state to the presence client after a
subscription refresh. subscription refresh.
3.2. Use Case for Setting a Minimum Rate for Notifications 3.2. Use Case for Setting a Minimum Rate for Notifications
A location application is monitoring the movement of a target. In A location application is monitoring the movement of a target. In
order to decrease the processing and network load, the location order to decrease the processing and network load, the location
application has made a subscription to a Location Server with a set application has made a subscription to a Location Server with a set
of location filters [I-D.ietf-geopriv-loc-filters] that specify of location filters [RFC6447] that specify trigger criteria, e.g., to
trigger criteria, e.g. to send an update only when the target has send an update only when the target has moved at least n meters.
moved at least n meters. However, the application is also interested However, the application is also interested in receiving the current
in receiving the current state periodically even if the state of the state periodically, even if the state of the target has not changed
target has not changed enough to satisfy any of the trigger criteria, enough to satisfy any of the trigger criteria, e.g., has not moved at
e.g., has not moved at least n meters within the period. least n meters within the period.
The location application sets a minimum rate of notifications and The location application sets a minimum rate of notifications and
include it in the subscription sent to the Location Server. The "min- includes it in the subscription sent to the Location Server. The
rate" parameter indicates the minimum number of notifications per "min-rate" parameter indicates the minimum number of notifications
second the notifier needs to generate. per second the notifier needs to generate.
The location application can also modify the minimum rate of The location application can modify the minimum rate of notifications
notifications during the lifetime of the subscription. For example, during the lifetime of the subscription. For example, when the
when the subscription to the movement of a target is made, the subscription to the movement of a target is made, the notifier may
notifier may not have the location information available. Thus, the not have the location information available. Thus, the first
first notification might be empty, or certain values might be absent. notification might be empty or certain values might be absent. An
An important use case is placing constraints on when complete state important use case is placing constraints on when complete state
should be provided after creating the subscription. Once state is should be provided after creating the subscription. Once state is
acquired and the second notification is sent, the subscriber updates acquired and the second notification is sent, the subscriber updates
or changes the "min-rate" parameter to a more sensible value. This or changes the "min-rate" parameter to a more sensible value. This
update can be performed in the response to the notification that update can be performed in the response to the notification that
contains the complete state information. contains the complete state information.
3.3. Use Case for Specifying an Adaptive Minimum Rate of Notifications 3.3. Use Case for Specifying an Adaptive Minimum Rate of Notifications
The minimum rate mechanism introduces a static and instantaneous rate The minimum rate mechanism introduces a static and instantaneous rate
control without the functionality to increase or decrease the control without the functionality to increase or decrease the
notification rate adaptively. However, there are some applications notification rate adaptively. However, there are some applications
that would work better with an adaptive minimum rate control. that would work better with an adaptive minimum rate control.
A location application is monitoring the movement of a target. In A location application is monitoring the movement of a target. In
order to decrease the processing in the application, the location order to decrease the processing in the application, the location
application wants to make a subscription that dynamically decreases application wants to make a subscription that dynamically decreases
the minimum rate of notifications if the target has sent out several the minimum rate of notifications if the target has sent out several
notifications recently. However, if there have have been only few notifications recently. However, if there have been only few recent
recent notifications by the target, the location application wants notifications by the target, the location application wants the
the minimum rate of notifications to increase. minimum rate of notifications to increase.
The location application sets an adaptive minimum rate of The location application sets an adaptive minimum rate of
notifications and include it in the subscription sent to the Location notifications and includes it in the subscription sent to the
Server. The "adaptive-min-rate" parameter value is used by the Location Server. The "adaptive-min-rate" parameter value is used by
notifier to dynamically calculate the actual maximum time between two the notifier to dynamically calculate the actual maximum time between
notifications. In order to dynamically calculate the maximum time, two notifications. In order to dynamically calculate the maximum
the notifier takes into consideration the rate at which notifications time, the notifier takes into consideration the rate at which
have been sent recently. In the adaptive minimum rate mechanism the notifications have been sent recently. In the adaptive minimum rate
notifier can increase or decrease the notification rate compared to mechanism, the notifier can increase or decrease the notification
the minimum rate mechanism based on the recent number of rate compared to the minimum rate mechanism based on the recent
notifications sent out in the last period. number of notifications sent out in the last period.
The location application can also modify the "adaptive-min-rate" The location application can also modify the "adaptive-min-rate"
parameter during the lifetime of the subscription. parameter during the lifetime of the subscription.
3.4. Requirements 3.4. Requirements
REQ1: The subscriber must be able to set a maximum rate of REQ1: The subscriber must be able to set a maximum rate of
notifications in a specific subscription. notifications in a specific subscription.
REQ2: The subscriber must be able to set a minimum rate of REQ2: The subscriber must be able to set a minimum rate of
notifications in a specific subscription. notifications in a specific subscription.
REQ3: The subscriber must be able to set an adaptive minimum rate REQ3: The subscriber must be able to set an adaptive minimum rate
of notifications in a specific subscription, which adjusts of notifications in a specific subscription, which adjusts
the minimum rate of notifications based on a moving average. the minimum rate of notifications based on a moving average.
REQ4: It must be possible to apply the maximum rate, the minimum REQ4: It must be possible to apply the maximum rate, the minimum
rate and the adaptive minimum rate mechanisms all together, rate, and the adaptive minimum rate mechanisms all together,
or in any combination, in a specific subscription. or in any combination, in a specific subscription.
REQ5: It must be possible to use any of the different rate control REQ5: It must be possible to use any of the different rate control
mechanisms in subscriptions to any events. mechanisms in subscriptions to any events.
REQ6: It must be possible to use any of the different rate control REQ6: It must be possible to use any of the different rate control
mechanisms together with any other event filtering mechanisms together with any other event filtering
mechanisms. mechanisms.
REQ7: The notifier must be allowed to use a policy in which the REQ7: The notifier must be allowed to use a policy in which the
maximum rate, minimum rate and adaptive minimum rate maximum rate, minimum rate, and adaptive minimum rate
parameters are adjusted from the value given by the parameters are adjusted from the value given by the
subscriber. subscriber.
For example, due to congestion reasons, local policy at For example, due to congestion, local policy at the
the notifier could temporarily dictate a policy that in notifier could temporarily dictate a policy that in effect
effect further decreases the maximum rate of further decreases the maximum rate of notifications. In
notifications. In another example, the notifier can another example, the notifier could increase the
increase the subscriber proposed maximum rate so that at subscriber-proposed maximum rate so that at least one
least one notification is generated during the remainder notification is generated during the remainder of the
of the subscription lifetime. subscription lifetime.
REQ8: The different rate control mechanisms must address corner REQ8: The different rate control mechanisms must address corner
cases for setting the notification rates appropriately. At a cases for setting the notification rates appropriately. At a
minimum, the mechanisms must address the situation when the minimum, the mechanisms must address the situation in which
time between two notifications would exceed the subscription the time between two notifications exceeds the subscription
duration and should provide procedures for avoiding this duration and should provide procedures for avoiding this
situation. situation.
REQ9: The different rate control mechanisms must be possible to be REQ9: It must be possible to invoke, modify, or remove the
invoked, modified, or removed in the course of an active different rate control mechanisms in the course of an active
subscription. subscription.
REQ10: The different rate control mechanisms must allow for the REQ10: The different rate control mechanisms must allow for the
application of authentication and integrity protection application of authentication and integrity protection
mechanisms to subscriptions invoking that mechanism. mechanisms to subscriptions invoking that mechanism.
4. Basic Operations 4. Basic Operations
4.1. Subscriber Behavior 4.1. Subscriber Behavior
In general, the way in which a subscriber generates SUBSCRIBE In general, a subscriber generates SUBSCRIBE requests and processes
requests and processes NOTIFY requests is according to RFC 3265 NOTIFY requests as described in RFC 3265 [RFC3265].
[RFC3265].
A subscriber that wants to have a maximum, minimum or adaptive A subscriber that wants to have a maximum, minimum, or adaptive
minimum rate of event notifications in a specific event subscription minimum rate of event notifications in a specific event subscription
does so by including a "max-rate", "min-rate" or "adaptive-min-rate" does so by including a "max-rate", "min-rate", or "adaptive-min-rate"
Event header field parameter(s) as part of the SUBSCRIBE request. Event header field parameter(s) as part of the SUBSCRIBE request.
A subscriber that wants to update a previously agreed event rate A subscriber that wants to update a previously agreed event rate
control parameter does so by including the updated "max-rate", "min- control parameter does so by including the updated "max-rate", "min-
rate" or "adaptive-min-rate" Event header field parameter(s) as part rate", or "adaptive-min-rate" Event header field parameter(s) as part
of a subsequent SUBSCRIBE request or a 2xx response to the NOTIFY of a subsequent SUBSCRIBE request or a 2xx response to the NOTIFY
request. If the subscriber did not include at least one of the "max- request. If the subscriber does not include at least one of the
rate", "min-rate" or "adaptive-min-rate" header field parameters in "max-rate", "min-rate", or "adaptive-min-rate" header field
the most recent SUBSCRIBE request in a given dialog, the subscriber parameters in the most recent SUBSCRIBE request in a given dialog,
MUST NOT include an Event header field with any of those parameters the subscriber MUST NOT include an Event header field with any of
in a 2xx response to a NOTIFY request in that dialog. those parameters in a 2xx response to a NOTIFY request in that
dialog.
4.2. Notifier Behavior 4.2. Notifier Behavior
In general, the way in which a notifier processes SUBSCRIBE requests In general, a notifier processes SUBSCRIBE requests and generates
and generates NOTIFY requests is according to RFC 3265 [RFC3265]. NOTIFY requests as described in RFC 3265 [RFC3265].
A notifier that supports the different rate control mechanisms MUST A notifier that supports the different rate control mechanisms MUST
adjust its rate of notification according to the rate control values adjust its rate of notification according to the rate control values
agreed with the subscriber. If the notifier needs to lower the agreed with the subscriber. If the notifier needs to lower the
subscription expiration value or if a local policy or other subscription expiration value, or if a local policy or other
implementation-determined constraint at the notifier can not satisfy implementation-determined constraint at the notifier cannot satisfy
the rate control request, then the notifier can adjust (i.e. increase the rate control request, then the notifier can adjust (i.e.,
or decrease) appropriately the subscriber requested rate control increase or decrease) appropriately the subscriber-requested rate
values. The notifier MUST reflect back the possibly adjusted rate control values. The notifier MUST reflect back the possibly adjusted
control values in a "max-rate", "min-rate" or "adaptive-min-rate" rate control values in a "max-rate", "min-rate", or "adaptive-min-
Subscription-State header field parameter of the subsequent NOTIFY rate" Subscription-State header field parameter of the subsequent
requests. NOTIFY requests.
5. Operation of the Maximum Rate Mechanism 5. Operation of the Maximum Rate Mechanism
5.1. Subscriber Behavior 5.1. Subscriber Behavior
A subscriber that wishes to apply a maximum rate to notifications in A subscriber that wishes to apply a maximum rate to notifications in
a subscription MUST construct a SUBSCRIBE request that includes the a subscription MUST construct a SUBSCRIBE request that includes the
"max-rate" Event header field parameter. This parameter specifies "max-rate" Event header field parameter. This parameter specifies
the requested maximum number of notifications per second. The value the requested maximum number of notifications per second. The value
of this parameter is a positive real number given by a finite decimal of this parameter is a positive real number given by a finite decimal
representation. representation.
Note that the grammar in section 9.2 constrains this value to be
between 0.0000000001 and 99.9999999999. Zero is not an allowed
value.
Note that the witnessed notification rate may not conform to the Note that the witnessed notification rate may not conform to the
"max-rate" value for a number of reasons. For example, network "max-rate" value for a number of reasons. For example, network
jitter and retransmissions may result in the subscriber receiving jitter and retransmissions may result in the subscriber receiving
the notifications more frequent than the "max-rate" value the notifications more frequently than the "max-rate" value
recommends. recommends.
A subscriber that wishes to update the previously agreed maximum rate A subscriber that wishes to update the previously agreed maximum rate
of notifications MUST include the updated "max-rate" Event header of notifications MUST include the updated "max-rate" Event header
field parameter in a subsequent SUBSCRIBE request or a 2xx response field parameter in a subsequent SUBSCRIBE request or a 2xx response
to the NOTIFY request. to the NOTIFY request.
A subscriber that wishes to remove the maximum rate control from A subscriber that wishes to remove the maximum rate control from
notifications MUST indicate so by not including a "max-rate" Event notifications MUST indicate so by not including a "max-rate" Event
header field parameter in a subsequent SUBSCRIBE request or a 2xx header field parameter in a subsequent SUBSCRIBE request or a 2xx
skipping to change at page 10, line 30 skipping to change at page 10, line 34
A notifier that does not understand this extension will not reflect A notifier that does not understand this extension will not reflect
the "max-rate" Subscription-State header field parameter in the the "max-rate" Subscription-State header field parameter in the
NOTIFY requests; the absence of this parameter indicates to the NOTIFY requests; the absence of this parameter indicates to the
subscriber that no rate control is supported by the notifier. subscriber that no rate control is supported by the notifier.
A compliant notifier MUST NOT generate a notification if the interval A compliant notifier MUST NOT generate a notification if the interval
since the most recent notification is less than the reciprocal value since the most recent notification is less than the reciprocal value
of the "max-rate" parameter, except when generating the notification of the "max-rate" parameter, except when generating the notification
either upon receipt of a SUBSCRIBE request, when the subscription either upon receipt of a SUBSCRIBE request, when the subscription
state is changing from "pending" to "active" state or upon state is changing from "pending" to "active" state, or upon
termination of the subscription (the last notification). termination of the subscription (the last notification).
When a local policy dictates a maximum rate for notifications, a When a local policy dictates a maximum rate for notifications, a
notifier will not generate notifications more frequently than the notifier will not generate notifications more frequently than the
local policy maximum rate, even if the subscriber is not asking for local policy maximum rate, even if the subscriber is not asking for
maximum rate control. The notifier MAY inform the subscriber about maximum rate control. The notifier MAY inform the subscriber about
such local policy maximum rate using the "max-rate" Subscription- such a local policy maximum rate using the "max-rate" Subscription-
State header field parameter included in subsequent NOTIFY requests. State header field parameter included in subsequent NOTIFY requests.
Retransmissions of NOTIFY requests are not affected by the maximum Retransmissions of NOTIFY requests are not affected by the maximum
rate mechanism, i.e., the maximum rate mechanism only applies to the rate mechanism, i.e., the maximum rate mechanism only applies to the
generation of new transactions. In other words, the maximum rate generation of new transactions. In other words, the maximum rate
mechanism does not in any way break or modify the normal mechanism does not in any way break or modify the normal
retransmission mechanism specified in RFC 3261 [RFC3261]. retransmission mechanism specified in RFC 3261 [RFC3261].
5.3. Selecting the Maximum Rate 5.3. Selecting the Maximum Rate
Special care needs to be taken when selecting the maximum rate. For Special care needs to be taken when selecting the maximum rate. For
example, the maximum rate could potentially set a minimum time value example, the maximum rate could potentially set a minimum time value
between notifications that exceeds the subscription expiration value. between notifications that exceeds the subscription expiration value.
Such a configuration would effectively quench the notifier, resulting Such a configuration would effectively quench the notifier, resulting
in exactly two notifications to be generated. If the subscriber in exactly two notifications being generated. If the subscriber
requests a maximum rate that would result in no notification before requests a maximum rate that would result in no notification before
the subscription expiration, the notifier MUST increase the maximum the subscription expiration, the notifier MUST increase the maximum
rate and set it to the reciprocal value of the subscription rate and set it to the reciprocal value of the remaining subscription
expiration time left. According to RFC 3265 [RFC3265] the notifier expiration time. According to RFC 3265 [RFC3265], the notifier may
may also shorten the subscription expiry anytime during an active also shorten the subscription expiry anytime during an active
subscription. If the subscription expiry is shortened during an subscription. If the subscription expiry is shortened during an
active subscription, the notifier MUST also increase the "max-rate" active subscription, the notifier MUST also increase the "max-rate"
value and set it to reciprocal value of the reduced subscription value and set it to the reciprocal value of the reduced subscription
expiration time. expiration time.
In some cases it makes sense to pause the notification stream on an In some cases, it makes sense to temporarily pause the notification
existing subscription dialog on a temporary basis without terminating stream on an existing subscription dialog without terminating the
the subscription, e.g. due to inactivity on the application user subscription, e.g., due to inactivity on the application user
interface. Whenever a subscriber discovers the need to perform the interface. Whenever a subscriber discovers the need to perform the
notification pause operation, it SHOULD set the maximum rate to the notification pause operation, it SHOULD set the maximum rate to the
reciprocal value of the remaining subscription expiration value. reciprocal value of the remaining subscription expiration value.
This results in receiving no further notifications until the This results in receiving no further notifications until the
subscription expires or the subscriber sends a SUBSCRIBE request subscription expires or the subscriber sends a SUBSCRIBE request
resuming notifications. resuming notifications.
The notifier MAY decide to increase or decrease the proposed "max- The notifier MAY decide to increase or decrease the proposed "max-
rate" value by the subscriber based on its local policy, static rate" value by the subscriber based on its local policy, static
configuration or other implementation-determined constraints. In configuration, or other implementation-determined constraints. In
addition, different event packages MAY define additional constraints addition, different event packages MAY define other constraints for
for the allowed maximum rate ranges. Such constraints are out of the the allowed maximum rate ranges. Such constraints are out of the
scope of this specification. scope of this specification.
5.4. The Maximum Rate Mechanism for Resource List Server 5.4. The Maximum Rate Mechanism for the Resource List Server
When applied to a list subscription [RFC4662], the maximum rate When applied to a list subscription [RFC4662], the maximum rate
mechanism has some additional considerations. Specifically, the mechanism has some additional considerations. Specifically, the
maximum rate applies to the aggregate notification stream resulting maximum rate applies to the aggregate notification stream resulting
from the list subscription, rather than explicitly controlling the from the list subscription, rather than explicitly controlling the
notification of each of the implied constituent events. Moreover, notification of each of the implied constituent events. Moreover,
the RLS can use the maximum rate mechanism on its own to control the the RLS can use the maximum rate mechanism on its own to control the
rate of the back-end subscriptions to avoid overflowing its buffer. rate of the back-end subscriptions to avoid overflowing its buffer.
The notifier is responsible for sending out event notifications upon The notifier is responsible for sending event notifications upon
state changes of the subscribed resource. We can model the notifier state changes of the subscribed resource. We can model the notifier
as consisting of four components: the event state resource(s), the as consisting of four components: the event state resource(s), the
Resource List Server (RLS) (or any other notifier), a notification RLS (or any other notifier), a notification buffer, and finally the
buffer, and finally the subscriber, or watcher of the event state, as subscriber, or watcher of the event state, as shown in Figure 1.
shown in Figure 1.
+--------+ +--------+
| Event | | Event |
+--------+ |Resource| +--------+ +--------+ |Resource| +--------+
| Event | +--------+ | Event | | Event | +--------+ | Event |
|Resource| | |Resource| |Resource| | |Resource|
+---.=---+ | +---=----+ +---.=---+ | +---=----+
`-.. | _.--' `-.. | _.--'
``-._ | _.--' ``-._ | _.--'
+'--'--'-+ +'--'--'-+
skipping to change at page 12, line 32 skipping to change at page 12, line 34
|Buffer|<======'max-rate| |Buffer|<======'max-rate|
| | `--------' | | `--------'
)--.---( )--.---(
| |
| |
.---+---. .---+---.
| Event | | Event |
|Watcher| |Watcher|
`-------' `-------'
Figure 1: Model for the Resource List Server (RLS) Supporting Figure 1: Model for the RLS Supporting Event Rate Control
Throttling
In short, the RLS reads event state changes from the event state In short, the RLS reads event state changes from the event state
resource, either by creating a back end subscription, or by other resource, either by creating a back-end subscription or by other
means; it packages them into event notifications and submits them means; it packages them into event notifications and submits them
into the output buffer. The rate at which this output buffer drains into the output buffer. The rate at which this output buffer drains
is controlled by the subscriber via the maximum rate mechanism. When is controlled by the subscriber via the maximum rate mechanism. When
a set of notifications are batched together, the way in which a set of notifications are batched together, the way in which
overlapping resource state is handled depends on the type of the overlapping resource state is handled depends on the type of the
resource state: resource state:
In theory, there are many buffer policies that the notifier could In theory, there are many buffer policies that the notifier could
implement. However, we only concentrate on two practical buffer implement. However, we only concentrate on two practical buffer
policies in this specification, leaving additional ones for policies in this specification, leaving additional ones for
further study and out of the scope of this specification. These further study and out of the scope of this specification. These
two buffer policies depend on the mode in which the notifier is two buffer policies depend on the mode in which the notifier is
operating. operating.
Full-state: Last (most recent) full state notification of each Full-state: Last (most recent) full-state notification of each
resource is sent out, and all others in the buffer are discarded. resource is sent out, and all others in the buffer are discarded.
This policy applies to those event packages that carry full-state This policy applies to those event packages that carry full-state
notifications. notifications.
Partial-state: The state deltas of each buffered partial Partial-state: The state deltas of each buffered partial
notification per resource are merged, and the resulting notification per resource are merged, and the resulting
notification is sent out. This policy applies to those event notification is sent out. This policy applies to those event
packages that carry partial-state notifications. packages that carry partial-state notifications.
5.5. Buffer Policy Description 5.5. Buffer Policy Description
5.5.1. Partial State Notifications 5.5.1. Partial-State Notifications
With partial notifications, the notifier needs to maintain a separate With partial notifications, the notifier needs to maintain a separate
buffer for each subscriber since each subscriber may have a different buffer for each subscriber since each subscriber may have a different
value for the maximum rate of notifications. The notifier will value for the maximum rate of notifications. The notifier will
always need to keep both a copy of the current full state of the always need to keep both a copy of the current full state of the
resource F, as well as the last successfully communicated full state resource F, as well as the last successfully communicated full state
view F' of the resource in a specific subscription. The construction view F' of the resource in a specific subscription. The construction
of a partial notification then involves creating a difference of the of a partial notification then involves creating a difference of the
two states, and generating a notification that contains that two states, and generating a notification that contains that
difference. difference.
When the maximum rate mechanism is applied to the subscription, it is When the maximum rate mechanism is applied to the subscription, it is
important that F' is replaced with F only when the difference of F important that F' be replaced with F only when the difference of F
and F' was already included in a partial state notification to the and F' is already included in a partial-state notification to the
subscriber allowed by the maximum rate mechanism. Additionally, the subscriber allowed by the maximum rate mechanism. Additionally, the
notifier implementation SHOULD check to see that the size of an notifier implementation SHOULD check to see that the size of an
accumulated partial state notification is smaller than the full accumulated partial state notification is smaller than the full
state, and if not, the notifier SHOULD send the full state state, and if not, the notifier SHOULD send the full-state
notification instead. notification instead.
5.5.2. Full State Notifications 5.5.2. Full-State Notifications
With full state notifications, the notifier only needs to keep the With full-state notifications, the notifier only needs to keep the
full state of the resource, and when that changes, send the resulting full state of the resource, and when that changes, send the resulting
notification over to the subscriber. notification to the subscriber.
When the maximum rate mechanism is applied to the subscription, the When the maximum rate mechanism is applied to the subscription, the
notifier receives the state changes of the resource, and generates a notifier receives the state changes of the resource and generates a
notification. If there is a pending notification, the notifier notification. If there is a pending notification, the notifier
simply replaces that notification with the new notification, simply replaces that notification with the new notification,
discarding the older state. discarding the older state.
5.6. Estimated Bandwidth Savings 5.6. Estimated Bandwidth Savings
It is difficult to estimate the total bandwidth savings accrued by It is difficult to estimate the total bandwidth savings accrued by
using the maximum rate mechanism over a subscription, since such using the maximum rate mechanism over a subscription, since such
estimates will vary depending on the usage scenarios. However, it is estimates will vary depending on the usage scenarios. However, it is
easy to see that given a subscription where several full state easy to see that given a subscription where several full-state
notifications would have normally been sent in any given interval set notifications would have normally been sent in any given interval set
by the "max-rate" parameter, only a single notification is sent by the "max-rate" parameter, only a single notification is sent
during the same interval when using the maximum rate mechanism during the same interval when using the maximum rate mechanism,
yielding bandwidth savings of several times the notification size. yielding bandwidth savings of several times the notification size.
With partial-state notifications, drawing estimates is further With partial-state notifications, drawing estimates is further
complicated by the fact that the states of consecutive updates may or complicated by the fact that the states of consecutive updates may or
may not overlap. However, even in the worst case scenario, where may not overlap. However, even in the worst-case scenario, where
each partial update is to a different part of the full state, a rate each partial update is to a different part of the full state, a rate
controlled notification merging all of these n partial states controlled notification merging all of these n partial states
together should at a maximum be the size of a full-state update. In together should at a maximum be the size of a full-state update. In
this case, the bandwidth savings are approximately n times the size this case, the bandwidth savings are approximately n times the size
of the header fields of the NOTIFY request. of the header fields of the NOTIFY request.
It is also true that there are several compression schemes available It is also true that there are several compression schemes available
that have been designed to save bandwidth in SIP, e.g., SigComp that have been designed to save bandwidth in SIP, e.g., SigComp
[RFC3320] and TLS compression [RFC3943]. However, such compression [RFC3320] and TLS compression [RFC3943]. However, such compression
schemes are complementary rather than competing mechanisms to the schemes are complementary rather than competing mechanisms to the
skipping to change at page 14, line 43 skipping to change at page 14, line 43
6.1. Subscriber Behavior 6.1. Subscriber Behavior
A subscriber that wishes to apply a minimum rate to notifications in A subscriber that wishes to apply a minimum rate to notifications in
a subscription MUST construct a SUBSCRIBE request that includes the a subscription MUST construct a SUBSCRIBE request that includes the
"min-rate" Event header field parameter. This parameter specifies "min-rate" Event header field parameter. This parameter specifies
the requested minimum number of notifications per second. The value the requested minimum number of notifications per second. The value
of this parameter is a positive real number given by a finite decimal of this parameter is a positive real number given by a finite decimal
representation. representation.
Note that the grammar in section 9.2 constrains this value to be
between 0.0000000001 and 99.9999999999. Zero is not an allowed
value.
A subscriber that wishes to update the previously agreed minimum rate A subscriber that wishes to update the previously agreed minimum rate
of notifications MUST include the updated "min-rate" Event header of notifications MUST include the updated "min-rate" Event header
field parameter in a subsequent SUBSCRIBE request or a 2xx response field parameter in a subsequent SUBSCRIBE request or a 2xx response
to the NOTIFY request. to the NOTIFY request.
A subscriber that wishes to remove the minimum rate control from A subscriber that wishes to remove the minimum rate control from
notifications MUST indicate so by not including a "min-rate" Event notifications MUST indicate so by not including a "min-rate" Event
header field parameter in a subsequent SUBSCRIBE request or a 2xx header field parameter in a subsequent SUBSCRIBE request or a 2xx
response to the NOTIFY request. response to the NOTIFY request.
The main consequence for the subscriber when applying the minimum The main consequence for the subscriber when applying the minimum
rate mechanism is that it can receive a notification even if nothing rate mechanism is that it can receive a notification even if nothing
has changed in the current state of the notifier. However, RFC 5839 has changed in the current state of the notifier. However, RFC 5839
[RFC5839] defines a mechanism that allows suppressing a NOTIFY [RFC5839] defines a mechanism that allows suppression of a NOTIFY
request or a NOTIFY request body if the state has not changed. request or a NOTIFY request body if the state has not changed.
6.2. Notifier Behavior 6.2. Notifier Behavior
A notifier that supports the minimum rate mechanism MUST extract the A notifier that supports the minimum rate mechanism MUST extract the
value of the "min-rate" Event header field parameter from a SUBSCRIBE value of the "min-rate" Event header field parameter from a SUBSCRIBE
request or a 2xx response to the NOTIFY request and use it as the request or a 2xx response to the NOTIFY request and use it as the
suggested minimum number of notifications per second. This value can suggested minimum number of notifications per second. This value can
be adjusted by the notifier, as defined in Section 6.3. be adjusted by the notifier, as defined in Section 6.3.
A compliant notifier MUST reflect back the possibly adjusted minimum A compliant notifier MUST reflect back the possibly adjusted minimum
rate of notifications in a "min-rate" Subscription-State header field rate of notifications in a "min-rate" Subscription-State header field
parameter of the subsequent NOTIFY requests. The indicated "min- parameter of the subsequent NOTIFY requests. The indicated "min-
rate" value is adopted by the notifier, and the notification rate is rate" value is adopted by the notifier, and the notification rate is
adjusted accordingly. adjusted accordingly.
A notifier that does not understand this extension, will not reflect A notifier that does not understand this extension will not reflect
the "min-rate" Subscription-State header field parameter in the the "min-rate" Subscription-State header field parameter in the
NOTIFY requests; the absence of this parameter indicates to the NOTIFY requests; the absence of this parameter indicates to the
subscriber that no rate control is supported by the notifier. subscriber that no rate control is supported by the notifier.
A compliant notifier MUST generate notifications when state changes A compliant notifier MUST generate notifications when state changes
occur or when the time since the most recent notification exceeds the occur or when the time since the most recent notification exceeds the
reciprocal value of the "min-rate" parameter. Depending on the event reciprocal value of the "min-rate" parameter. Depending on the event
package and subscriber preferences indicated in the SUBSCRIBE package and subscriber preferences indicated in the SUBSCRIBE
request, the NOTIFY request sent as a result of a minimum rate request, the NOTIFY request sent as a result of a minimum rate
mechanism MUST contain either the current full state or the partial mechanism MUST contain either the current full state or the partial
state showing the difference between the current state and the last state showing the difference between the current state and the last
successfully communicated state. If the subscriber and the notifier successfully communicated state. If the subscriber and the notifier
support the procedures in RFC 5839 [RFC5839] the complete NOTIFY support the procedures in RFC 5839 [RFC5839], the complete NOTIFY
request or the NOTIFY request body can be suppressed if the state has request or the NOTIFY request body can be suppressed if the state has
not changed from the previous notification. not changed from the previous notification.
Retransmissions of NOTIFY requests are not affected by the minimum Retransmissions of NOTIFY requests are not affected by the minimum
rate mechanism, i.e., the minimum rate mechanism only applies to the rate mechanism, i.e., the minimum rate mechanism only applies to the
generation of new transactions. In other words, the minimum rate generation of new transactions. In other words, the minimum rate
mechanism does not in any way break or modify the normal mechanism does not in any way break or modify the normal
retransmission mechanism. retransmission mechanism.
6.3. Selecting the Minimum Rate 6.3. Selecting the Minimum Rate
The minimum rate mechanism can be used to generate a lot of The minimum rate mechanism can be used to generate a lot of
notifications, creating additional processing load for the notifier. notifications, creating additional processing load for the notifier.
Some of the notifications may also be unnecessary possibly repeating Some of the notifications may also be unnecessary possibly repeating
already known state information to the subscriber. It is difficult already known state information to the subscriber. It is difficult
to provide generic guidelines for the acceptable minimum rate value to provide generic guidelines for the acceptable minimum rate value
ranges, however the subscriber SHOULD request for the lowest possible ranges; however, the subscriber SHOULD request the lowest possible
minimum rate. Different event packages MAY define additional minimum rate. Different event packages MAY define other constraints
constraints for the allowed minimum rate values. Such constraints for the allowed minimum rate values. Such constraints are out of the
are out of the scope of this specification. scope of this specification.
The notifier MAY decide to increase or decrease the proposed "min- The notifier MAY decide to increase or decrease the proposed "min-
rate" value by the subscriber based on its local policy, static rate" value by the subscriber based on its local policy, static
configuration or other implementation-determined constraints. configuration, or other implementation-determined constraints.
7. Operation of the Adaptive Minimum Rate Mechanism 7. Operation of the Adaptive Minimum Rate Mechanism
7.1. Subscriber Behavior 7.1. Subscriber Behavior
A subscriber that wishes to apply an adaptive minimum rate to A subscriber that wishes to apply an adaptive minimum rate to
notifications in a subscription MUST construct a SUBSCRIBE request notifications in a subscription MUST construct a SUBSCRIBE request
that includes the "adaptive-min-rate" Event header field parameter. that includes the "adaptive-min-rate" Event header field parameter.
This parameter specifies an adaptive minimum number of notifications This parameter specifies an adaptive minimum number of notifications
per second. The value of this parameter is a positive real number per second. The value of this parameter is a positive real number
given by a finite decimal representation. given by a finite decimal representation.
Note that the grammar in section 9.2 constrains this value to be
between 0.0000000001 and 99.9999999999. Zero is not an allowed
value.
A subscriber that wishes to update the previously agreed adaptive A subscriber that wishes to update the previously agreed adaptive
minimum rate of notifications MUST include the updated "adaptive-min- minimum rate of notifications MUST include the updated "adaptive-min-
rate" Event header field parameter in a subsequent SUBSCRIBE request rate" Event header field parameter in a subsequent SUBSCRIBE request
or a 2xx response to the NOTIFY request. or a 2xx response to the NOTIFY request.
A subscriber that wishes to remove the adaptive minimum rate control A subscriber that wishes to remove the adaptive minimum rate control
from notifications MUST indicate so by not including a "adaptive-min- from notifications MUST indicate so by not including an "adaptive-
rate" Event header field parameter in a subsequent SUBSCRIBE request min-rate" Event header field parameter in a subsequent SUBSCRIBE
or a 2xx response to the NOTIFY request. request or a 2xx response to the NOTIFY request.
The main consequence for the subscriber when applying the adaptive The main consequence for the subscriber when applying the adaptive
minimum rate mechanism is that it can receive a notification even if minimum rate mechanism is that it can receive a notification, even if
nothing has changed in the current state of the notifier. However, nothing has changed in the current state of the notifier. However,
RFC 5839 [RFC5839] defines a mechanism that allows suppressing a RFC 5839 [RFC5839] defines a mechanism that allows suppression of a
NOTIFY request or a NOTIFY request body if the state has not changed. NOTIFY request or a NOTIFY request body if the state has not changed.
7.2. Notifier Behavior 7.2. Notifier Behavior
A notifier that supports the adaptive minimum rate mechanism MUST A notifier that supports the adaptive minimum rate mechanism MUST
extract the value of the "adaptive-min-rate" Event header parameter extract the value of the "adaptive-min-rate" Event header parameter
from a SUBSCRIBE request or a 2xx response to the NOTIFY request and from a SUBSCRIBE request or a 2xx response to the NOTIFY request and
use it to calculate the actual maximum time between two notifications use it to calculate the actual maximum time between two
as defined in Section 7.4. notifications, as defined in Section 7.4.
The "adaptive-min-rate" value can be adjusted by the notifier, as The "adaptive-min-rate" value can be adjusted by the notifier, as
defined in Section 7.3. defined in Section 7.3.
A compliant notifier MUST reflect back the possibly adjusted adaptive A compliant notifier MUST reflect back the possibly adjusted adaptive
minimum rate of notifications in an "adaptive-min-rate" Subscription- minimum rate of notifications in an "adaptive-min-rate" Subscription-
State header field parameter of the subsequent NOTIFY requests. The State header field parameter of the subsequent NOTIFY requests. The
indicated "adaptive-min-rate" value is adopted by the notifier, and indicated "adaptive-min-rate" value is adopted by the notifier, and
the notification rate is adjusted accordingly. the notification rate is adjusted accordingly.
skipping to change at page 17, line 25 skipping to change at page 17, line 35
subscriber that no rate control is supported by the notifier. subscriber that no rate control is supported by the notifier.
A compliant notifier MUST generate notifications when state changes A compliant notifier MUST generate notifications when state changes
occur or when the time since the most recent notification exceeds the occur or when the time since the most recent notification exceeds the
value calculated using the formula defined in Section 7.4. Depending value calculated using the formula defined in Section 7.4. Depending
on the event package and subscriber preferences indicated in the on the event package and subscriber preferences indicated in the
SUBSCRIBE request, the NOTIFY request sent as a result of a minimum SUBSCRIBE request, the NOTIFY request sent as a result of a minimum
rate mechanism MUST contain either the current full state or the rate mechanism MUST contain either the current full state or the
partial state showing the difference between the current state and partial state showing the difference between the current state and
the last successfully communicated state. If the subscriber and the the last successfully communicated state. If the subscriber and the
notifier support the procedures in RFC 5839 [RFC5839] the complete notifier support the procedures in RFC 5839 [RFC5839], the complete
NOTIFY request or the NOTIFY request body can be suppressed if the NOTIFY request or the NOTIFY request body can be suppressed if the
state has not changed from the previous notification. state has not changed from the previous notification.
The adaptive minimum rate mechanism is implemented as follows: The adaptive minimum rate mechanism is implemented as follows:
1) When a subscription is first created, the notifier creates a 1) When a subscription is first created, the notifier creates a
record ("count" parameter) that keeps track of the number of record ("count" parameter) that keeps track of the number of
notifications that have been sent in the "period". The "count" notifications that have been sent in the "period". The "count"
parameter is initialized to contain a history of having sent a parameter is initialized to contain a history of having sent a
"period * adaptive-min-rate" number of notifications for the "period * adaptive-min-rate" number of notifications for the
skipping to change at page 17, line 48 skipping to change at page 18, line 12
2) The "timeout" value is calculated according to the equation given 2) The "timeout" value is calculated according to the equation given
in Section 7.4. in Section 7.4.
3) If the timeout period passes without a NOTIFY request being sent 3) If the timeout period passes without a NOTIFY request being sent
in the subscription, then the current resource state is sent in the subscription, then the current resource state is sent
(subject to any filtering associated with the subscription). (subject to any filtering associated with the subscription).
4) Whenever a NOTIFY request is sent (regardless of whether due to a 4) Whenever a NOTIFY request is sent (regardless of whether due to a
"timeout" event or a state change), the notifier updates the "timeout" event or a state change), the notifier updates the
notification history record stored in the "count" parameter, notification history record stored in the "count" parameter,
recalculates the value of "timeout," and returns to step 3. recalculates the value of "timeout", and returns to step 3.
Retransmissions of NOTIFY requests are not affected by the timeout, Retransmissions of NOTIFY requests are not affected by the timeout,
i.e., the timeout only applies to the generation of new transactions. i.e., the timeout only applies to the generation of new transactions.
In other words, the timeout does not in any way break or modify the In other words, the timeout does not in any way break or modify the
normal retransmission mechanism specified in RFC 3261 [RFC3261]. normal retransmission mechanism specified in RFC 3261 [RFC3261].
7.3. Selecting the Adaptive Minimum Rate 7.3. Selecting the Adaptive Minimum Rate
The adaptive minimum rate mechanism can be used to generate a lot of The adaptive minimum rate mechanism can be used to generate a lot of
notifications, creating additional processing load for the notifier. notifications, creating additional processing load for the notifier.
Some of the notifications may also be unnecessary possibly repeating Some of the notifications may also be unnecessary, possibly repeating
already known state information to the subscriber. It is difficult already known state information to the subscriber. It is difficult
to provide generic guidelines for the acceptable adaptive minimum to provide generic guidelines for the acceptable adaptive minimum
rate value ranges, however the subscriber SHOULD request for the rate value ranges; however, the subscriber SHOULD request the lowest
lowest possible adaptive minimum rate value. Different event possible adaptive minimum rate value. Different event packages MAY
packages MAY define additional constraints for the allowed adaptive define other constraints for the allowed adaptive minimum rate
minimum rate values. Such constraints are out of the scope of this values. Such constraints are out of the scope of this specification.
specification.
The notifier MAY decide to increase or decrease the proposed The notifier MAY decide to increase or decrease the proposed
"adaptive-min-rate" value based on its local policy, static "adaptive-min-rate" value based on its local policy, static
configuration or other implementation-determined constraints. configuration, or other implementation-determined constraints.
7.4. Calculating the Timeout 7.4. Calculating the Timeout
The formula used to vary the absolute pacing in a way that will meet The formula used to vary the absolute pacing in a way that will meet
the adaptive minimum rate requested over the period is given in the adaptive minimum rate requested over the period is given in
equation (1): equation (1):
timeout = count / ((adaptive-min-rate ^ 2) * period) (1) timeout = count / ((adaptive-min-rate ^ 2) * period) (1)
The output of the formula, "timeout", is the time to the next The output of the formula, "timeout", is the time to the next
notification, expressed in seconds. The formula has three inputs: notification, expressed in seconds. The formula has three inputs:
adaptive-min-rate: The value of the "adaptive-min-rate" parameter adaptive-min-rate: The value of the "adaptive-min-rate" parameter
conveyed in the Subscription-State header field. conveyed in the Subscription-State header field.
period: The rolling average period, in seconds. The granularity of period: The rolling average period, in seconds. The granularity of
the values for the "period" parameter is set by local policy at the values for the "period" parameter is set by local policy at
the notifier, however the notifier MUST choose a value greater the notifier; however, the notifier MUST choose a value greater
than the reciprocal value of the "adaptive-min-rate" parameter. than the reciprocal value of the "adaptive-min-rate" parameter.
It is also RECOMMENDED that the notifier chooses a "period" It is also RECOMMENDED that the notifier choose a "period"
parameter several times larger than reciprocal value of the parameter several times larger than reciprocal value of the
"adaptive-min-rate" parameter in order to maximize the "adaptive-min-rate" parameter in order to maximize the
effectiveness of the equation (1). It is an implementation effectiveness of equation (1). It is an implementation decision
decision whether the notifier uses the same value of the "period" whether the notifier uses the same value of the "period" parameter
parameter for all subscriptions or individual values for each for all subscriptions or individual values for each subscription.
subscription.
count: The number of notifications that have been sent during the count: The number of notifications that have been sent during the
last "period" of seconds not including any retransmissions of last "period" of seconds, not including any retransmissions of
requests. requests.
In case both the maximum rate and the adaptive minimum rate In case both the maximum rate and the adaptive minimum rate
mechanisms are used in the same subscription the formula used to mechanisms are used in the same subscription, the formula used to
dynamically calculate the timeout is given in equation (2): dynamically calculate the timeout is given in equation (2):
timeout = MAX[(1/max-rate), count/((adaptive-min-rate ^ 2)*period)] (2) timeout = MAX[(1/max-rate), count/((adaptive-min-rate ^ 2)*period)] (2)
max-rate: The value of the "max-rate" parameter conveyed in the max-rate: The value of the "max-rate" parameter conveyed in the
Subscription-State header field. Subscription-State header field.
The formula in (2) makes sure that for all the possible values of the The formula in (2) makes sure that for all the possible values of the
"max-rate" and "adaptive-min-rate" parameters, with "adaptive-min- "max-rate" and "adaptive-min-rate" parameters, with "adaptive-min-
rate" < "max-rate", the timeout never results in a lower value than rate" < "max-rate", the timeout never results in a lower value than
the reciprocal value of the "max-rate" parameter. the reciprocal value of the "max-rate" parameter.
In some situation it may be beneficial for the notifier to achieve an In some situations, it may be beneficial for the notifier to achieve
adaptive minimum rate in a different way than the algorithm detailed an adaptive minimum rate in a different way than the algorithm
in this document allows. However, the notifier MUST comply with any detailed in this document allows. However, the notifier MUST comply
"max-rate" or "min-rate" parameters that have been negotiated. with any "max-rate" or "min-rate" parameters that have been
negotiated.
8. Usage of the Maximum Rate, Minimum Rate and Adaptive Minimum Rate 8. Usage of the Maximum Rate, Minimum Rate, and Adaptive Minimum Rate
Mechanisms in a combination Mechanisms in a Combination
Applications can subscribe to an event package using all the rate Applications can subscribe to an event package using all the rate
control mechanisms individually, or in combination; in fact there is control mechanisms individually, or in combination; in fact there is
no technical incompatibility among them. However there are some no technical incompatibility among them. However, there are some
combinations of the different rate control mechanisms that make combinations of the different rate control mechanisms that make
little sense to be used together. This section lists all the little sense to be used together. This section lists all the
combinations that are possible to insert in a subscription; the combinations that are possible to insert in a subscription; the
utility to use each combination in a subscription is also analyzed. ability to use each combination in a subscription is also analyzed.
maximum rate and minimum rate: This combination allows to reduce the maximum rate and minimum rate: This combination allows a reduced
notification rate, but at the same time assures the reception of notification rate, but at the same time assures the reception of
periodic notifications. periodic notifications.
A subscriber SHOULD choose a "min-rate" value lower than the "max- A subscriber SHOULD choose a "min-rate" value lower than the "max-
rate" value, otherwise the notifier MUST adjust the subscriber rate" value, otherwise, the notifier MUST adjust the subscriber
provided "min-rate" value to a value equal to or lower than the provided "min-rate" value to a value equal to or lower than the
"max-rate" value. "max-rate" value.
maximum rate and adaptive minimum rate: It works in a similar way as maximum rate and adaptive minimum rate: It works in a similar way as
the combination above, but with the difference that the interval the combination above, but with the difference that the interval
at which notifications are assured changes dynamically. at which notifications are assured changes dynamically.
A subscriber SHOULD choose a "adaptive-min-rate" value lower than A subscriber SHOULD choose an "adaptive-min-rate" value lower than
the "max-rate" value, otherwise the notifier MUST adjust the the "max-rate" value, otherwise, the notifier MUST adjust the
subscriber provided "adaptive-min-rate" value to a value equal to subscriber provided "adaptive-min-rate" value to a value equal to
or lower than the "max-rate" value. or lower than the "max-rate" value.
minimum rate and adaptive minimum rate: When using the adaptive minimum rate and adaptive minimum rate: When using the adaptive
minimum rate mechanism, frequent state changes in a short period minimum rate mechanism, frequent state changes in a short period
can result in no notifications for a longer period following the can result in no notifications for a longer period following the
short period. The addition of the minimum rate mechanism ensures short period. The addition of the minimum rate mechanism ensures
the subscriber always receives notifications after a specified that the subscriber always receives notifications after a
interval. specified interval.
A subscriber SHOULD choose a "min-rate" value lower than the A subscriber SHOULD choose a "min-rate" value lower than the
"adaptive-min-rate" value, otherwise the notifier MUST NOT "adaptive-min-rate" value, otherwise, the notifier MUST NOT
consider the "min-rate" value. consider the "min-rate" value.
maximum rate, minimum rate and adaptive minimum rate: This maximum rate, minimum rate, and adaptive minimum rate: This
combination makes little sense to be used although not forbidden. combination makes little sense to be used, although it is not
forbidden.
A subscriber SHOULD choose a "min-rate" and "adaptive-min-rate" A subscriber SHOULD choose a "min-rate" and "adaptive-min-rate"
values lower than the "max-rate" value, otherwise the notifier values lower than the "max-rate" value, otherwise, the notifier
MUST adjust the subscriber provided "min-rate" and "adaptive-min- MUST adjust the subscriber provided "min-rate" and "adaptive-min-
rate" values to a value equal to or lower than the "max-rate" rate" values to a value equal to or lower than the "max-rate"
value. value.
A subscriber SHOULD choose a "min-rate" value lower than the A subscriber SHOULD choose a "min-rate" value lower than the
"adaptive-min-rate" value, otherwise the notifier MUST NOT "adaptive-min-rate" value, otherwise, the notifier MUST NOT
consider the "min-rate" value. consider the "min-rate" value.
9. Protocol Element Definitions 9. Protocol Element Definitions
This section describes the protocol extensions required for the This section describes the protocol extensions required for the
different rate control mechanisms. different rate control mechanisms.
9.1. "max-rate", "min-rate" and "adaptive-min-rate" Header Field 9.1. "max-rate", "min-rate", and "adaptive-min-rate" Header Field
Parameters Parameters
The "max-rate", "min-rate" and "adaptive-min-rate" parameters are The "max-rate", "min-rate", and "adaptive-min-rate" parameters are
added to the rule definitions of the Event header field and the added to the rule definitions of the Event header field and the
Subscription-State header field in RFC 3265 [RFC3265] grammar. Usage Subscription-State header field in RFC 3265 [RFC3265] grammar. Usage
of this parameter is described in Section 5, Section 6 and Section 7. of this parameter is described in Sections 5, 6, and 7.
9.2. Grammar 9.2. Grammar
This section describes the Augmented BNF [RFC5234] definitions for This section describes the Augmented BNF [RFC5234] definitions for
the new header field parameters. Note that we derive here from the the new header field parameters. Note that we derive here from the
ruleset present in RFC 3265 [RFC3265], adding additional alternatives ruleset present in RFC 3265 [RFC3265], adding additional alternatives
to the alternative sets of "event-param" and "subexp-params" defined to the alternative sets of "event-param" and "subexp-params" defined
therein. therein.
event-param = max-rate-param event-param = max-rate-param
skipping to change at page 21, line 26 skipping to change at page 21, line 34
subexp-params = max-rate-param subexp-params = max-rate-param
/ min-rate-param / min-rate-param
/ amin-rate-param / amin-rate-param
max-rate-param = "max-rate" EQUAL max-rate-param = "max-rate" EQUAL
(1*2DIGIT ["." 1*10DIGIT]) (1*2DIGIT ["." 1*10DIGIT])
min-rate-param = "min-rate" EQUAL min-rate-param = "min-rate" EQUAL
(1*2DIGIT ["." 1*10DIGIT]) (1*2DIGIT ["." 1*10DIGIT])
amin-rate-param = "adaptive-min-rate" EQUAL amin-rate-param = "adaptive-min-rate" EQUAL
(1*2DIGIT ["." 1*10DIGIT]) (1*2DIGIT ["." 1*10DIGIT])
9.3. Event Header Field Usage in Responses to the NOTIFY request 9.3. Event Header Field Usage in Responses to the NOTIFY Request
This table expands the table described in Section 7.2 of RFC 3265 This table expands the table described in Section 7.2 of RFC 3265
[RFC3265] allowing the Event header field to appear in a 2xx response [RFC3265], allowing the Event header field to appear in a 2xx
to a NOTIFY request. The use of the Event header field in responses response to a NOTIFY request. The use of the Event header field in
other than 2xx to NOTIFY requests is undefined and out of scope of responses other than 2xx to NOTIFY requests is undefined and out of
this specification. scope of this specification.
Header field where proxy ACK BYE CAN INV OPT REG PRA SUB NOT Header field where proxy ACK BYE CAN INV OPT REG PRA SUB NOT
----------------------------------------------------------------- -----------------------------------------------------------------
Event 2xx - - - - - - - - o Event 2xx - - - - - - - - o
A subscriber that wishes to update the previously agreed value for A subscriber that wishes to update the previously agreed value for
maximum, minimum or adaptive minimum rate of notifications MUST maximum, minimum, or adaptive minimum rate of notifications MUST
include all desired values for the "max-rate", "min-rate" and include all desired values for the "max-rate", "min-rate", and
"adaptive-min-rate" parameters in an Event header field of the 2xx "adaptive-min-rate" parameters in an Event header field of the 2xx
response to a NOTIFY request. Any of the other header field response to a NOTIFY request. Any of the other header field
parameters currently defined for the Event header field by other parameters currently defined for the Event header field by other
specifications do not have a meaning if the Event header field is specifications do not have a meaning if the Event header field is
included in the 2xx response to the NOTIFY request. These header included in the 2xx response to the NOTIFY request. These header
field parameters MUST be ignored by the notifier, if present. field parameters MUST be ignored by the notifier, if present.
The event type listed in the Event header field of the 2xx response The event type listed in the Event header field of the 2xx response
to the NOTIFY request MUST match the event type of the Event header to the NOTIFY request MUST match the event type of the Event header
field in the corresponding NOTIFY request. field in the corresponding NOTIFY request.
10. IANA Considerations 10. IANA Considerations
This specification registers three new SIP header field parameters, This specification registers three new SIP header field parameters in
defined by the following information which is to be added to the the "Header Field Parameters and Parameter Values" sub-registry of
Header Field Parameters and Parameter Values sub-registry under the "Session Initiation Protocol (SIP) Parameters" registry.
http://www.iana.org/assignments/sip-parameters.
Predefined Predefined
Header Field Parameter Name Values Reference Header Field Parameter Name Values Reference
-------------------- --------------- ---------- --------- -------------------- --------------- ---------- ---------
Event max-rate No [RFCxxxx] Event max-rate No [RFC6446]
Subscription-State max-rate No [RFCxxxx] Subscription-State max-rate No [RFC6446]
Event min-rate No [RFCxxxx] Event min-rate No [RFC6446]
Subscription-State min-rate No [RFCxxxx] Subscription-State min-rate No [RFC6446]
Event adaptive-min-rate No [RFCxxxx] Event adaptive-min-rate No [RFC6446]
Subscription-State adaptive-min-rate No [RFCxxxx] Subscription-State adaptive-min-rate No [RFC6446]
(Note to the RFC Editor: please replace "xxxx" with the RFC number of
this specification, when assigned.)
This specification also updates the reference defining the Event This specification also updates the reference defining the Event
header field in the Header Fields sub-registry under header field in the "Header Fields" sub-registry of the "Session
http://www.iana.org/assignments/sip-parameters. Initiation Protocol (SIP) Parameters" registry.
Header Name compact Reference Header Name compact Reference
----------- ------- ------------------ ----------- ------- ------------------
Event o [RFC3265][RFCxxxx] Event o [RFC3265][RFC6446]
(Note to the RFC Editor: please replace "xxxx" with the RFC number of
this specification, when assigned.)
11. Security Considerations 11. Security Considerations
Naturally, the security considerations listed in RFC 3265 [RFC3265], Naturally, the security considerations listed in RFC 3265 [RFC3265],
which the rate control mechanisms described in this document extends, which the rate control mechanisms described in this document extends,
apply in entirety. In particular, authentication and message apply in their entirety. In particular, authentication and message
integrity SHOULD be applied to subscriptions with this extension. integrity SHOULD be applied to subscriptions with this extension.
RFC 3265 [RFC3265] recommends the integrity protection of the Event RFC 3265 [RFC3265] recommends the integrity protection of the Event
header field of SUBSCRIBE requests. Implementations of this header field of SUBSCRIBE requests. Implementations of this
extension SHOULD also provide integrity protection for the Event extension SHOULD also provide integrity protection for the Event
header field included in the 2xx response to the NOTIFY request. header field included in the 2xx response to the NOTIFY request.
Without integrity protection an eavesdropper could see and modify the Without integrity protection, an eavesdropper could see and modify
Event header field; or it could also manipulate the transmission of a the Event header field, or it could manipulate the transmission of a
200 (OK) response to the NOTIFY request in order to suppress or flood 200 (OK) response to the NOTIFY request to suppress or flood
notifications without the subscriber seeing what caused the problem. notifications without the subscriber seeing what caused the problem.
When the maximum rate mechanism involves partial state notifications, When the maximum rate mechanism involves partial-state notifications,
the security considerations listed in RFC 5263 [RFC5263] apply in the security considerations listed in RFC 5263 [RFC5263] apply in
entirety. their entirety.
12. Acknowledgments 12. Acknowledgments
Thanks to Pekka Pessi, Dean Willis, Eric Burger, Alex Audu, Alexander Thanks to Pekka Pessi, Dean Willis, Eric Burger, Alex Audu, Alexander
Milinski, Jonathan Rosenberg, Cullen Jennings, Adam Roach, Hisham Milinski, Jonathan Rosenberg, Cullen Jennings, Adam Roach, Hisham
Khartabil, Dale Worley, Martin Thomson, Byron Campen, Alan Johnston, Khartabil, Dale Worley, Martin Thomson, Byron Campen, Alan Johnston,
Michael Procter, Janet Gunn and Ari Keranen for support and/or review Michael Procter, Janet Gunn, and Ari Keranen for support and/or
of this work. review of this work.
Thanks to Brian Rosen for the idea of the minimum and adaptive Thanks to Brian Rosen for the idea of the minimum and adaptive
minimum rate mechanisms, and Adam Roach for the work on the algorithm minimum rate mechanisms, and to Adam Roach for the work on the
for the adaptive minimum rate mechanism and other feedback. algorithm for the adaptive minimum rate mechanism and other feedback.
13. References 13. References
13.1. Normative References 13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002. June 2002.
[RFC3265] Roach, A., "Session Initiation Protocol (SIP)-Specific [RFC3265] Roach, A., "Session Initiation Protocol (SIP)-Specific
Event Notification", RFC 3265, June 2002. Event Notification", RFC 3265, June 2002.
[RFC4662] Roach, A., Campbell, B., and J. Rosenberg, "A Session [RFC4662] Roach, A., Campbell, B., and J. Rosenberg, "A Session
Initiation Protocol (SIP) Event Notification Extension for Initiation Protocol (SIP) Event Notification Extension for
Resource Lists", RFC 4662, August 2006. Resource Lists", RFC 4662, August 2006.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5263] Lonnfors, M., Costa-Requena, J., Leppanen, E., and H. [RFC5263] Lonnfors, M., Costa-Requena, J., Leppanen, E., and H.
Khartabil, "Session Initiation Protocol (SIP) Extension Khartabil, "Session Initiation Protocol (SIP) Extension
for Partial Notification of Presence Information", for Partial Notification of Presence Information",
RFC 5263, September 2008. RFC 5263, September 2008.
13.2. Informative References 13.2. Informative References
[I-D.ietf-geopriv-loc-filters]
Mahy, R., Rosen, B., and H. Tschofenig, "Filtering
Location Notifications in the Session Initiation Protocol
(SIP)", draft-ietf-geopriv-loc-filters-11 (work in
progress), March 2010.
[RFC3320] Price, R., Bormann, C., Christoffersson, J., Hannu, H., [RFC3320] Price, R., Bormann, C., Christoffersson, J., Hannu, H.,
Liu, Z., and J. Rosenberg, "Signaling Compression Liu, Z., and J. Rosenberg, "Signaling Compression
(SigComp)", RFC 3320, January 2003. (SigComp)", RFC 3320, January 2003.
[RFC3680] Rosenberg, J., "A Session Initiation Protocol (SIP) Event [RFC3680] Rosenberg, J., "A Session Initiation Protocol (SIP) Event
Package for Registrations", RFC 3680, March 2004. Package for Registrations", RFC 3680, March 2004.
[RFC3842] Mahy, R., "A Message Summary and Message Waiting [RFC3842] Mahy, R., "A Message Summary and Message Waiting
Indication Event Package for the Session Initiation Indication Event Package for the Session Initiation
Protocol (SIP)", RFC 3842, August 2004. Protocol (SIP)", RFC 3842, August 2004.
skipping to change at page 24, line 35 skipping to change at page 24, line 29
Initiation Protocol (SIP)", RFC 3856, August 2004. Initiation Protocol (SIP)", RFC 3856, August 2004.
[RFC3857] Rosenberg, J., "A Watcher Information Event Template- [RFC3857] Rosenberg, J., "A Watcher Information Event Template-
Package for the Session Initiation Protocol (SIP)", Package for the Session Initiation Protocol (SIP)",
RFC 3857, August 2004. RFC 3857, August 2004.
[RFC3943] Friend, R., "Transport Layer Security (TLS) Protocol [RFC3943] Friend, R., "Transport Layer Security (TLS) Protocol
Compression Using Lempel-Ziv-Stac (LZS)", RFC 3943, Compression Using Lempel-Ziv-Stac (LZS)", RFC 3943,
November 2004. November 2004.
[RFC5839] Niemi, A. and D. Willis, "An Extension to Session [RFC5839] Niemi, A. and D. Willis, Ed., "An Extension to Session
Initiation Protocol (SIP) Events for Conditional Event Initiation Protocol (SIP) Events for Conditional Event
Notification", RFC 5839, May 2010. Notification", RFC 5839, May 2010.
[RFC6447] Mahy, R., Rosen, B., and H. Tschofenig, "Filtering
Location Notifications in the Session Initiation Protocol
(SIP)", RFC 6447, January 2012.
Authors' Addresses Authors' Addresses
Aki Niemi Aki Niemi
Nokia Nokia
P.O. Box 407 P.O. Box 407
NOKIA GROUP, FIN 00045 NOKIA GROUP, FIN 00045
Finland Finland
Phone: +358 50 389 1644 Phone: +358 50 389 1644
Email: aki.niemi@nokia.com EMail: aki.niemi@nokia.com
Krisztian Kiss Krisztian Kiss
Nokia Nokia
200 South Mathilda Ave 200 South Mathilda Ave
Sunnyvale, CA 94086 Sunnyvale, CA 94086
US US
Phone: +1 650 391 5969 Phone: +1 650 391 5969
Email: krisztian.kiss@nokia.com EMail: krisztian.kiss@nokia.com
Salvatore Loreto Salvatore Loreto
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 Jorvas 02420
Finland Finland
Email: salvatore.loreto@ericsson.com EMail: salvatore.loreto@ericsson.com
 End of changes. 123 change blocks. 
247 lines changed or deleted 244 lines changed or added

This html diff was produced by rfcdiff 1.41. The latest version is available from http://tools.ietf.org/tools/rfcdiff/