SIPPING Working Group A. Johnston
Internet-Draft H. Sinnreich
Expires: July 13, 2005 MCI
A. Clark
Telchemy Incorporated
A. Pendleton
Nortel Networks
January 12, 2005
SIP Service Quality Reporting Event
draft-johnston-sipping-rtcp-summary-06
Status of this Memo
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Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
This document discusses the motivation and requirements for the
delivery of service quality reports from SIP endpoints to
non-participants in the session. A publication mechanism using a new
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SIP events package is proposed as a solution. An event package
"svcqual" and an application/svcqual MIME type is defined in this
document along with some example call flows.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Motivations for the Approach . . . . . . . . . . . . . . . . . 3
4. Why SNMP is Not Appropriate . . . . . . . . . . . . . . . . . 4
5. SIP Events Approach . . . . . . . . . . . . . . . . . . . . . 4
6. Use of PUBLISH Method . . . . . . . . . . . . . . . . . . . . 4
7. Event Package Formal Definition . . . . . . . . . . . . . . . 5
7.1 Event Package Name . . . . . . . . . . . . . . . . . . . . 5
7.2 Event Package Parameters . . . . . . . . . . . . . . . . . 5
7.3 SUBSCRIBE Bodies . . . . . . . . . . . . . . . . . . . . . 5
7.4 Subscription Duration . . . . . . . . . . . . . . . . . . 5
7.5 NOTIFY Bodies . . . . . . . . . . . . . . . . . . . . . . 5
7.6 Voice Quality Event Syntax . . . . . . . . . . . . . . . . 6
7.7 Voice Quality Metric Definitions . . . . . . . . . . . . . 8
7.8 Call Flows and Syntax Examples . . . . . . . . . . . . . . 11
7.8.1 End of Session Notification using PUBLISH . . . . . . 11
7.8.2 End of Session Notification using NOTIFY . . . . . . . 13
7.8.3 Mid Session Threshold Violation using PUBLISH . . . . 15
7.8.4 Mid Session Threshold Violation using NOTIFY . . . . . 18
7.9 IANA Considerations . . . . . . . . . . . . . . . . . . . 20
7.9.1 SIP Event Package Registration . . . . . . . . . . . . 20
7.9.2 application/rtcp-xr MIME Registration . . . . . . . . 21
7.10 Security Considerations . . . . . . . . . . . . . . . . . 21
7.11 Updates since -04 . . . . . . . . . . . . . . . . . . . . 22
7.12 Updates since -03 . . . . . . . . . . . . . . . . . . . . 22
7.13 Contributors . . . . . . . . . . . . . . . . . . . . . . . 22
8. Informative References . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 23
Intellectual Property and Copyright Statements . . . . . . . . 24
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1. Introduction
This document defines a new performance report SIP event package and
a new MIME type for VoIP performance metrics. In addition, the
document includes the requirements, motivation, and a discussion why
SNMP alone is not sufficient for this problem space. Using this
mechanism, a SIP user agent (UA) can publish performance reports, or
a performance quality collector can subscribe to receive performance
reports from a particular SIP UA. The application/svcqual MIME type
defined in this document is based on the information contained in a
RTCP-XR VOIP block and is highly optimized and useful for voice
session quality. As VoIP is currently has the most immediate need
for the real time quality reports available with this package, it has
been defined first. However, the event package is designed to be
extensible - existing MIME types which carry performance reports
could be used, or other application/media specific MIME types could
be defined and used within this framework.
2. Requirements
REQ-1: An authorized third party should be able to receive selected
performance reports on a near real time basis.
REQ-2: The VoIP application should not have to store large amounts of
information.
REQ-3: The VoIP application must be able to authenticate the third
party.
REQ-4: The performance report information must be able to be
transferred securely.
REQ-6: The reports will include or be associated with dialog
identifiers for correlation purposes.
3. Motivations for the Approach
Monitor the application:
While QoS monitoring in network elements using for example SNMP is
quite common, only the VoIP applications in endpoints are close
enough to the experience of individual users, on a call by call basis
in endpoints as diverse as desktop SIP phones, PDAs, PCs or mobile
phones. For this reason, the approach taken here is to monitor the
voice quality at the application level and not in network elements.
Focus on voice specific impairments:
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RTCP extensions support the monitoring of various impairments such as
packet loss, delay and jitter, but more important, specific metrics
are included to measure burst errors that produce voice clipping.
Voice clipping is the most annoying impairment in VoIP due to network
congestion in the media path between VoIP applications.
4. Why SNMP is Not Appropriate
Since this type of QoS monitoring seems related to management, SNMP
could possibly be used to collect this type of data as well. SNMP is
however primarily used for management of network devices as they
relate to the infrastructure but is not typically used for management
of applications on that infrastructure. The focus of SIP is
applications and the performance management for those applications
cannot rely on SNMP. SNMP may be used to manage some aspects of the
physical device aspects of the SIP user agent
Specifically, SNMP may be used to manage the SIP user agent - the
phone, soft phone or gateway. However, the information available in
RTCP summary reports is of less interest to the management of the UA
and more of interest to the VoIP service provider. In many cases,
separate entities will be involved. For example, an enterprise may
manage their own SIP phones using SNMP, but a service provider
provides SIP and gateway services. It is unlikely a service provider
will have SNMP privileges and may not be able to manage NAT/firewall
traversal, etc. For these reasons, SNMP is not a good fit for this
"service level" management function.
5. SIP Events Approach
In this approach, a new SIP events package [6] is defined. The
intended methods to use for this event are PUBLISH [8] and
SUBSCRIBE/NOTIFY. A VoIP application will send performance data
using either of these methods to an entity which will make the
information available to other applications.
6. Use of PUBLISH Method
A VoIP application which supports this specification may send
performance report information using the PUBLISH method. An
application wishing to access this performance data maintains a State
Agent for the svcqual event package. The Request-URI of the PUBLISH
method is set to the address of the resource for the VoIP
application. The PUBLISH method is sent to the normal default
outbound proxy server of the VoIP application.
The use of PUBLISH by this event is unique in that it does not
require a soft or hard state to be maintained by either the Event
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Publication Agent (EPA) or the Event State Compositor (ESC).
Futhermore the information that is presented by the svcqual event in
a PUBLISH request is not expected to have an expiration, rather, the
information is associated with the timestamps in the event itself.
The primary intention of using PUBLISH for this event is reduction of
transaction processing.
The State Agent can use normal mechanisms for publication throttling
or rejection of the information as described in the PUBLISH [8]
specification.
7. Event Package Formal Definition
7.1 Event Package Name
This document defines a SIP Event Package as defined in RFC 3265 [2].
The event-package token name for this package is:
"svcqual"
7.2 Event Package Parameters
No event package parameters are defined.
7.3 SUBSCRIBE Bodies
No SUBSCRIBE bodies are described by this specification.
7.4 Subscription Duration
Subscriptions to this event package MAY range from minutes to weeks.
Subscriptions in hours or days are more typical and are RECOMMENDED.
The default subscription duration for this event package is one hour.
7.5 NOTIFY Bodies
There are two notify bodies: a general report and a threshold
report. The general report is used for periodic, mid-call reporting
and end of call reporting. The metrics provided by this event are
intended to be generically defined to allow both cumulative based and
short interval based reporting.
The threshold report is used when call quality degrades. The general
report is also included in the alert report to provide all of the
necessary diagnostic information.
This specification defines a new MIME type application/svcqual which
is a text encoding of the RTCP-XR statistics, with the addition of a
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few additional identifiers.
7.6 Voice Quality Event Syntax
This section describes the syntax extensions required for event
publication in SIP. The formal syntax definitions described in this
section are expressed in the Augmented BNF format [7] used in SIP
[2], and contains references to elements defined therein.
General Report Event:
VQEvent = VoiceQualityAlert /
(LocalMetrics [CLRF RemoteMetrics])
[DialogID]
LocalMetrics = ("LocalMetrics") HCOLON VoiceQualityMetrics
RemoteMetrics = ("RemoteMetrics") HCOLON VoiceQualityMetrics
VoiceQualityMetrics = ("VQMetrics") CLRF
TimeStampInfo CLRF
SessionDesc CLRF
CallID CLRF
Ssrc CRLF
JitterBuffer CRLF
PacketLoss CRLF
BurstLoss CLRF
GapLoss CLRF
Delay CLRF
Signal CLRF
Quality
TimeStampInfo = "Timestamps" EQUAL start-time SP stop-time
start-time = "start" COLON alphanum [*alphanum]
stop-time = "stop" COLON alphanum [*alphanum]
SessionDesc = ("SessionDesc") EQUAL cline mline aline
cline = "cline" COLON alphanum [*alphanum]
mline = "mline" COLON alphanum [*alphanum]
aline = "aline" COLON alphanum [*alphanum] [*aline]
CallID = ("CallID" / "i") COLON callid
callid = word [ "@" word ]
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Ssrc = ("Ssrc") COLON alphanum [*alphanum]
JitterBuffer = ("JitterBuffer") EQUAL jb-type SP jb-rate
SP jb-nom SP jb-max SP jb-abs-max
jb-type = ("type") COLON ("adapt" / "non-adapt" / "unknown"
/ "not available" )
jb-rate = ("rate") COLON 1*3DIGIT / notAvail
jb-max = ("max") COLON 1*3DIGIT / notAvail
jb-nom = ("nom") COLON 1*3DIGIT / notAvail
jb-absmax = ("abmax") COLON 1*3DIGIT / notAvail
PacketLoss = ("PktLoss") EQUAL loss-rate SP disc-rate
loss-rate = ("loss") 1*2DIGIT / notAvail
disc-rate = ("discard") COLON 1*2DIGIT / notAvail
BurstLoss = ("BurstLoss") EQUAL density SP length
GapLoss = ("GapLoss") EQUAL density SP length
density = ("density") COLON 1*4DIGIT / notAvail
length = ("length") COLON 1*4DIGIT / notAvail
Delay = ("Delay") EQUAL roundtrip SP endsys SP jitter
roundtrip = ("roundtrip") COLON 1*4DIGIT / notAvail
endsys = ("endsystem") COLON 1*4DIGIT / notAvail
jitter = ("jitter") COLON 1*3DIGIT / notAvail
Signal = ("Signal") EQ signal SP echo SP noise
signal = ("signalLevel") COLON 1*2DIGIT / notAvail
echo = ("echoReturnLoss") COLON 1*3DIGIT / notAvail
noise = ("noiseLevel") COLON 1*2DIGIT / notAvail
Quality = ("QualityScores") EQ r-lq SP r-cg SP r-cq-ext SP m-lq SP m-cq
r-lq = ("r-lq") COLON 1*3DIGIT / notAvail
r-cq = ("r-cq") COLON 1*3DIGIT / notAvail
r-cq-ext = ("r-cq-ext") COLON 1*3DIGIT / notAvail
m-lq = ("mos-lq") COLON DIGIT ["." 1*2DIGIT] / notAvail
m-cq = ("mos-cq") COLON DIGIT ["." 1*2DIGIT] / notAvail
DialogID = ("DialogID") COLON callid *(SEMI did-parm)
did-parm = to-tag / from-tag / generic-param
callid = token
to-tag = "to-tag" EQUAL token
from-tag = "from-tag" EQUAL token
VoiceQualityAlert = ("VQAlert") COLON SP ViolationMetric SP
Severity SP ViolationDirection
CRLF VoiceQualityMetrics
ViolationMetric = ("Type") COLON ("r-lq" / "r-cq" / "r-cq-ext" /
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"mos-lq" / "mos-cq" /
"burst" / "erl" /
"delay" / "loss" /
"siglvl" / "noiselvl" /
"jitter" / "discard" /
token )
ViolationDirection = ("Dir") COLON ("local" / "remote")
Severity = ("Severity") COLON ("Warning" / "Critical" /
"Clear")
notAvail = "not available" / "na"
7.7 Voice Quality Metric Definitions
Timestamp Information
This line will provide the start and stop time for the
metric measurement interval. In some cases, this could be
the entire call and in other cases could be only a very
short duration when threshold-based or interval-based
reporting are supporting.
Session Description
This line should provide media session information using the
Session Description Protocol (SDP)
for the local endpoint. The format defined only requires the
endpoint to send its "c=" line, "m=" line, and all related "a="
lines.
SSRC
This line provides the SSRC parameter that is transmited in the
RTP packets which should provide unique identification of the
media stream.
Jitter Buffer Information Line
The parameters in this line provide information about the
jitter buffer within the media endpoint.
Jitter Buffer Type
Indicator of the jitter buffer is adaptive or static.
When the jitter buffer is adaptive, then its size is being
dynamically adjusted to deal with varying levels of
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jitter. When non-adaptive, the jitter buffer size is
maintained at a fixed level.
Jitter Buffer Adaptation Rate
This represents the implementation specific adjustment
rate of a jitter buffer in adaptive mode.
Jitter Buffer Nomimal Delay
This is the current nominal jitter buffer delay in
milliseconds, which corresponds to the nominal jitter
buffer delay for packets that arrive exactly on time.
This parameter MUST be provided for both fixed and
adaptive jitter buffer implementations.
Jitter Buffer Maximum Delay
This is the current maximum jitter buffer delay in
milliseconds which corresponds to the earliest arriving
packet that would not be discarded. In simple queue
implementations this may correspond to the nominal size.
In adaptive jitter buffer implementations, this value may
dynamically vary up to JB abs max (see below).
Jitter Buffer Absolute Maximum Delay
This is the absolute maximum delay in milliseconds that
the adaptive jitter buffer can reach under worst case
conditions. If this value exceeds 65535 milliseconds,
then this field SHALL convey the value 65535. This
parameter MUST be provided for adaptive jitter buffer
implementations and its value MUST be set to JB maximum
for fixed jitter buffer implementations.
Packet Loss Information Line
The parameters in this line are general packet loss
metrics.
Packet Loss Ratio
The percentage of packets lost within the network during
the time period captured by the report.
Packet Discard Rate
The percentage of packets discarded due to jitter within
the network during the time period captured by the report.
Burst Loss Information Line
The parameters in this provide burst loss metrics.
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Burst Density
The percentage of packets lost and discarded within a
burst (high loss rate) period.
Burst Length (mS)
The mean length of a burst.
Gap Loss Information Line
The parameters in this provide random loss metrics.
Gap Density
The percentage of packets lost and discarded within a
gap (low loss rate) period.
Gap Length (mS)
The mean length of a gap
Delay Information Line
The parameters in this provide delay metrics.
Round Trip Delay (mS)
The round trip delay between RTP interfaces
End System Round Trip Delay (mS)
The "round trip" delay between the RTP interface and the
analog or trunk interface.
Jitter
Using definition from the RTCP, interarrival jitter is
defined to be the mean deviation of the difference in
packet spacing at the receiver compared to the sender for
a pair of packets. This metric is provided in
milliseconds.
Signal Information Line
The parameters in this provide analog impairment metrics.
Signal Level
The signal level in decibals during talkspurts.
Noise Level (dBm)
The signal level in decibals during silence periods.
Residual Echo Return Loss (dB)
The residual (uncancelled) echo level from the analog or
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trunk interface.
Quality Scores Information Line
This line provides various quality scores for the session.
R - Listening Quality
Estimated listening call quality expressed in a score from
0 - 100, per ITU-T standard G.107. The calculation of
this value should only involve impairments measured from
the listening direction.
R - Conversational Quality
Estimated conversational call quality expressed in a
score from 0 - 100, per ITU-T standard G.107.
R - Conversational Quality - External
Estimated external conversational transmission quality expressed
as a score from 0 - 100, per ITU-T standard G.107.
This value provides the score for the segment of the session
that is carried over a network segment external to the RTP
segment; for example a cellular network.
MOS-LQ
Estimated listening call quality expressed as a floating
point number between 0.0 and 5.0.
MOS-CQ
Estimated conversational call quality expressed as a
floating point number between 0.0 and 5.0.
7.8 Call Flows and Syntax Examples
This section shows a number of call flow examples showing how the
event package works.
7.8.1 End of Session Notification using PUBLISH
Alice Proxy/Registrar Collector Bob
| | | |
| | | |
| REGISTER Allow-Event:svcqual F1 | |
|------------------->| | |
| 200 OK F2 | | |
|<-------------------| | |
| INVITE F3 | | |
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|------------------->| | |
| | INVITE F4 | |
| |---------------------------------------->|
| | 200 OK F5 | |
| |<----------------------------------------|
| 200 OK F6 | | |
|<-------------------| | |
| ACK F7 | | |
|------------------->| | |
| | ACK F8 | |
| |---------------------------------------->|
| RTP | | |
|<============================================================>|
| RTCP | | |
|<============================================================>|
| | | |
| BYE F9 | | |
|------------------->| BYE F10 | |
| |---------------------------------------->|
| | 200 OK F11 | |
| |<----------------------------------------|
| 200 OK F12 | | |
|<-------------------| | |
| PUBLISH Event:svcqual F13 | |
|------------------->| | |
| | PUBLISH Event:svcqual F14 |
| |------------------->| |
| | 200 OK F15 | |
| |<-------------------| |
| 200 OK F16 | | |
|<-------------------| | |
Figure 1. Summary report sent after session termination.
In the call flow depicted in Figure 1, the following message format
is sent in F13:
PUBLISH sip:collector@example.com SIP/2.0
Via: SIP/2.0/UDP pc22.example.com;branch=z9hG4bK3343d7
Max-Forwards: 70
To:
From: Alice ;tag=a3343df32
Call-ID: 1890463548@alice.chicago.com
CSeq: 4331 PUBLISH
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
SUBSCRIBE, NOTIFY
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Event: svcqual
Accept: application/sdp, message/sipfrag
Content-Type: application/svcqual
Content-Length: ...
LocalMetrics:VQMetrics:
TimeStampInfo=start:10012004.18.23.43 stop:10012004.18.26.02
SessionDesc=cline:IN IP4 10.10.1.123 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.uac.chicago.com
Ssrc=fjuekdn393k
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:5 discard:2
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:200 endsystem:140 jitter:2
Signal=signalLevel:2 echoReturnLoss:14 noiseLevel:10
QualityScores=r-lq:90 r-cq:80 r-cq-ext:92
mos-lq:3.4 mos-cq:3.3
RemoteMetrics:VQMetrics:
TimeStampInfo=start:10012004.18.23.43 stop:10012004.18.26.02
SessionDesc=cline:IN IP4 11.1.1.150 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.uac.chicago.com
Ssrc=r3k3k99weid
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:2 discard:1
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:100 endsystem:140 jitter:2
Signal=signalLevel:2 echoReturnLoss:0 noiseLevel:9
QualityScores=r-lq:88 r-cq:80 r-cq-ext:92
mos-lq:3.3 mos-cq:3.3
DialogID:38419823470834;to-tag=8472761;from-tag=9123dh311
7.8.2 End of Session Notification using NOTIFY
Alice Proxy/Registrar Collector Bob
| | | |
| | | |
| REGISTER Allow-Event:svcqual F1 | |
|------------------->| | |
| 200 OK F2 | | |
|<-------------------| | |
| | SUBSCRIBE Event:svcqual F3 |
| |<-------------------| |
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| SUBSCRIBE Event:svcqual F4 | |
|<-------------------| | |
| 200 OK F5 | | |
|------------------->| | |
| | 200 OK F6 | |
| |------------------->| |
| INVITE F7 | | |
|------------------->| | |
| | INVITE F8 | |
| |---------------------------------------->|
| | 200 OK F9 | |
| |<----------------------------------------|
| 200 OK F10 | | |
|<-------------------| | |
| ACK F11 | | |
|------------------->| | |
| | ACK F12 | |
| |---------------------------------------->|
| RTP | | |
|<============================================================>|
| RTCP | | |
|<============================================================>|
| | | |
| BYE F13 | | |
|------------------->| BYE F14 | |
| |---------------------------------------->|
| | 200 OK F15 | |
| |<----------------------------------------|
| 200 OK F16 | | |
|<-------------------| | |
| NOTIFY Event:svcqual F17 | |
|------------------->| | |
| | NOTIFY Event:svcqual F18 |
| |------------------->| |
| | 200 OK F19 | |
| |<-------------------| |
| 200 OK F20 | | |
|<-------------------| | |
Figure 2. Summary report sent after session termination.
In the call flow depicted in Figure 2, the following message format
is sent in F17:
NOTIFY sip:collector@example.com SIP/2.0
Via: SIP/2.0/UDP pc22.example.com;branch=z9hG4bK3343d7
Max-Forwards: 70
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To: ;tag=43524545
From: Alice ;tag=a3343df32
Call-ID: 1890463548@alice.chicago.com
CSeq: 4321 NOTIFY
Contact:
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
SUBSCRIBE, NOTIFY
Event: svcqual
Accept: application/sdp, message/sipfrag
Subscription-State: active;expires=3600
Content-Type: application/svcqual
Content-Length: ...
LocalMetrics:VQMetrics:
TimeStampInfo=start:10012004.18.23.43 stop:10012004.18.26.02
SessionDesc=cline:IN IP4 11.1.1.150 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.chicago.com
Ssrc=fjuekdn393k
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:5 discard:2
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:200 endsystem:140 jitter:2
Signal=signalLevel:2 echoReturnLoss:14 noiseLevel:10
QualityScores=r-lq:90 r-cq:80 r-cq-ext:92
mos-lq:3.4 mos-cq:3.3
RemoteMetrics:VQMetrics:
SessionDesc=cline:IN IP4 11.1.1.150 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.uac.chicago.com
Ssrc=r3k3k99weidtd
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:2 discard:1
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:100 endsystem:140 jitter:2
Signal=signalLevel:2 echoReturnLoss:0 noiseLevel:9
QualityScores=r-lq:88 r-cq:80 r-cq-ext:92
mos-lq:3.3 mos-cq:3.3
DialogID:38419823470834;to-tag=8472761;from-tag=9123dh311
7.8.3 Mid Session Threshold Violation using PUBLISH
Alice Proxy/Registrar Collector Bob
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| | | |
| INVITE F1 | | |
|------------------->| | |
| | INVITE F2 | |
| |---------------------------------------->|
| | 200 OK F3 | |
| |<----------------------------------------|
| 200 OK F4 | | |
|<-------------------| | |
| ACK F5 | | |
|------------------->| | |
| | ACK F6 | |
| |---------------------------------------->|
| RTP | | |
|<============================================================>|
| RTCP | | |
|<============================================================>|
| PUBLISH Event:svcqual F7 | |
|------------------->| | |
| | PUBLISH Event:svcqual F8 |
| |------------------->| |
| | 200 OK F9 | |
| |<-------------------| |
| 200 OK F10 | | |
|<-------------------| | |
| | | |
| BYE F12 | | |
|------------------->| BYE F13 | |
| |---------------------------------------->|
| | 200 OK F14 | |
| |<----------------------------------------|
| 200 OK F15 | | |
|<-------------------| | |
| PUBLISH Event:svcqual F16 | |
|------------------->| | |
| | PUBLISH Event:svcqual F17 |
| |------------------->| |
| | 200 OK F18 | |
| |<-------------------| |
| 200 OK F19 | | |
|<-------------------| | |
Figure 3. Summary report sent during session with threshold report.
In the call flow depicted in Figure 3, the following message format
is sent in F16:
PUBLISH sip:collector@chicago.example.com SIP/2.0
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Via: SIP/2.0/UDP pc22.example.com;branch=z9hG4bK3343d7
Max-Forwards: 70
To:
From: Alice ;tag=a3343df32
Call-ID: 1890463548@alice.chicago.com
CSeq: 4321 PUBLISH
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
SUBSCRIBE, NOTIFY
Event: svcqual
Accept: application/sdp, message/sipfrag
Content-Type: application/svcqual
Content-Length: ...
VQAlert: Type:r-lq Severity:Warning Dir:local
LocalMetrics:VQMetrics:
TimeStampInfo=start:10012004.19.01.04 stop:10012004.19.01.52
SessionDesc=cline:IN IP4 11.1.1.150 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.chicago.com
Ssrc=fjuekdn3
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:5 discard:2
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:200 endsystem:140 jitter:2
Signal=signalLevel:2 echoReturnLoss:14 noiseLevel:1
QualityScores=r-lq:82 r-cq:80 mos-lq:3.4 mos-cq:3.3
RemoteMetrics:VQMetrics:
SessionDesc=cline:IN IP4 11.1.1.150 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.uac.chicago.com
Ssrc=r3k3k99weidtd
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:2 discard:1
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:100 endsystem:140 jitter:2
Signal=signalLevel:2 echoReturnLoss:14 noiseLevel:1
QualityScosres=r-lq:81 r-cq:81 mos-lq:3.1 mos-cq:3.2
DialogID:38419823470834;to-tag=8472761;from-tag=9123dh311
This alert indicates that the quality of the call in progress, as calculated
using the Listening Quality transmission rating R , has degraded to an
unacceptable level. For futher troubleshooting of the problem, all metrics
are populated, including the remote values which were obtained via RTCP XR
in the endpoints.
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7.8.4 Mid Session Threshold Violation using NOTIFY
Alice Proxy/Registrar Collector Bob
| | | |
| | | |
| REGISTER Allow-Event:svcqual F1 | |
|------------------->| | |
| 200 OK F2 | | |
|<-------------------| | |
| | SUBSCRIBE Event:svcqual F3 |
| |<-------------------| |
| SUBSCRIBE Event:svcqual F4 | |
|<-------------------| | |
| 200 OK F5 | | |
|------------------->| | |
| | 200 OK F6 | |
| |------------------->| |
| INVITE F7 | | |
|------------------->| | |
| | INVITE F8 | |
| |---------------------------------------->|
| | 200 OK F9 | |
| |<----------------------------------------|
| 200 OK F10 | | |
|<-------------------| | |
| ACK F11 | | |
|------------------->| | |
| | ACK F12 | |
| |---------------------------------------->|
| RTP | | |
|<============================================================>|
| RTCP | | |
|<============================================================>|
| NOTIFY Event:svcqual F17 | |
|------------------->| | |
| | NOTIFY Event:svcqual F18 |
| |------------------->| |
| | 200 OK F19 | |
| |<-------------------| |
| 200 OK F20 | | |
|<-------------------| | |
| | | |
| BYE F13 | | |
|------------------->| BYE F14 | |
| |---------------------------------------->|
| | 200 OK F15 | |
| |<----------------------------------------|
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| 200 OK F16 | | |
|<-------------------| | |
| NOTIFY Event:svcqual F17 | |
|------------------->| | |
| | NOTIFY Event:svcqual F18 |
| |------------------->| |
| | 200 OK F19 | |
| |<-------------------| |
| 200 OK F20 | | |
|<-------------------| | |
Figure 4. Summary report sent during session with threshold report.
In the call flow depicted in Figure 2, the following message format
is sent in F17:
NOTIFY sip:collector@chicago.example.com SIP/2.0
Via: SIP/2.0/UDP pc22.example.com;branch=z9hG4bK3343d7
Max-Forwards: 70
To:
From: Alice ;tag=a3343df32
Call-ID: 1890463548@alice.chicago.com
CSeq: 4321 PUBLISH
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER,
SUBSCRIBE, NOTIFY
Event: svcqual
Accept: application/sdp, message/sipfrag
Content-Type: application/svcqual
Content-Length: ...
VQAlert: Type:r-lq Severity:Warning Dir:local
LocalMetrics:VQMetrics:
TimeStampInfo=start:10012004.19.01.04 stop:10012004.19.01.52
SessionDesc=cline:IN IP4 11.1.1.150 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.chicago.com
Ssrc=fjuekdn3
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:5 discard:2
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:200 endsystem:140
Signal=signalLevel:2 echoReturnLoss:14 noiseLevel:1
QualityScores=r-lq:82 r-cq:80 mos-lq:3.4 mos-cq:3.3
Remote:VQMetrics:
SessionDesc=cline:IN IP4 11.1.1.150 mline:audio 5002 RTP/AVP 0
aline:rtpmap:0 PCMU/8000 aline:ptime=20
CallID=1890463548@alice.uac.chicago.com
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Ssrc=r3k3k99weidtd
JitterBuffer=type:adapt rate:2 nom:40 max:80 abmax:120
PktLoss=loss:2 discard:1
BurstLoss=density:0 length:0
GapLoss=density:2 length:0
Delay=roundtrip:100 endsystem:140 jitter:2
Signal=signalLevel:2 echoReturnLoss:14 noiseLevel:1
QualityScosres=r-lq:81 r-cq:90 mos-lq:3.1 mos-cq:3.2
DialogID:38419823470834;to-tag=8472761;from-tag=9123dh311
This alert indicates that the quality of the call in progress, as calculated
using the Listening Quality transmission rating R , has degraded to an
unacceptable level. For futher troubleshooting of the problem, all metrics
are populated, including the remote values which were obtained via RTCP XR [4]
in the endpoints..
7.9 IANA Considerations
This document registers a new SIP Event Package and a new MIME type.
7.9.1 SIP Event Package Registration
Package name: svcqual
Type: package
Contact: Alan Johnston
Published Specification: This document
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7.9.2 application/rtcp-xr MIME Registration
MIME media type name: application
MIME subtype name: svcqual
Mandatory parameters: none
Optional parameters: none
Encoding considerations: text
Security considerations: See next section.
Interoperability considerations: none.
Published specification: This document.
Applications which use this media type: This document type is
being used in notifications of VoIP quality reports.
Additional Information:
Magic Number: None
File Extension: None
Macintosh file type code: "TEXT"
Personal and email address for further information: Alan Johnston
Intended usage: COMMON
Author/Change controller: The IETF.
7.10 Security Considerations
RTCP reports can contain sensitive information since they can provide
information about the nature and duration of a session established
between two endpoints. As a result, any third party wishing to
obtain this information should be properly authenticated and the
information transferred securely.
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7.11 Updates since -04
- Changed package name from "perfrpt" to "svcqual"
7.12 Updates since -03
- Removed discussion of alternative mechanisms
- Changed from NOTIFY transport to PUBLISH transport.
- Changed package name from "rtcp-xr" to "perfrpt"
- Corrected call flows.
- Minor updates to message body format.
- Added IANA registration for perfrpt SIP Event Package and
application/rtcp-xr MIME registration.
- Added more discussion for motivation and reasons why SNMP is not
suitable
7.13 Contributors
The authors would like to thank Rajesh Kumar, Dave Oran and Tom
Redman for their discussions.
8 Informative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[2] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
[3] Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson,
"RTP: A Transport Protocol for Real-Time Applications", STD 64,
RFC 3550, July 2003.
[4] Friedman, T., Caceres, R. and A. Clark, "RTP Control Protocol
Extended Reports (RTCP XR)", RFC 3611, November 2003.
[5] Huitema, C., "Real Time Control Protocol (RTCP) attribute in
Session Description Protocol (SDP)", RFC 3605, October 2003.
[6] Roach, A., "Session Initiation Protocol (SIP)-Specific Event
Notification", RFC 3265, June 2002.
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[7] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
[8] Niemi, A., "An Event State Publication Extension to the Session
Initiation Protocol (SIP)", draft-ietf-sip-publish-04 (work in
progress), May 2004.
Authors' Addresses
Alan Johnston
MCI
100 South 4th Street
St. Louis, MO 63104
EMail: alan.johnston@mci.com
Henry Sinnreich
MCI
400 International Parkway
Richardson, TX 75081
EMail: henry.sinnreich@mci.com
Alan Clark
Telchemy Incorporated
3360 Martins Farm Road, Suite 200
Suwanee, GA 30024
EMail: alan@telchemy.com
Amy Pendleton
Nortel Networks
2380 Performance Drive
Richardson, TX 75081
EMail: aspen@nortelnetworks.com
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