draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-06.txt   draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-07.txt 
XR Block Working Group J. Ott XR Block Working Group J. Ott
Internet-Draft V. Singh Internet-Draft V. Singh, Ed.
Intended status: Standards Track Aalto University Intended status: Standards Track Aalto University
Expires: January 06, 2014 I. Curcio Expires: April 04, 2014 I. Curcio
Nokia Research Center Nokia Research Center
July 05, 2013 October 01, 2013
RTP Control Protocol (RTCP) Extended Reports (XR) for Run Length RTP Control Protocol (RTCP) Extended Report (XR) for Run Length Encoding
Encoding (RLE) of Discarded Packets (RLE) of Discarded Packets
draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-06.txt draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-07
Abstract Abstract
The RTP Control Protocol (RTCP) is used in conjunction with the Real- The RTP Control Protocol (RTCP) is used in conjunction with the Real-
time Transport Protocol (RTP) in to provide a variety of short-term time Transport Protocol (RTP) in to provide a variety of short-term
and long-term reception statistics. The available reporting may and long-term reception statistics. The available reporting may
include aggregate information across longer periods of time as well include aggregate information across longer periods of time as well
as individual packet reporting. This document specifies a per-packet as individual packet reporting. This document specifies a per-packet
report metric capturing individual packets discarded from the jitter report metric capturing individual packets discarded from the de-
buffer after successful reception. jitter buffer after successful reception.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 06, 2014. This Internet-Draft will expire on April 04, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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skipping to change at page 2, line 15 skipping to change at page 2, line 15
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. XR Discard RLE Report Block . . . . . . . . . . . . . . . . . 4 3. XR Discard RLE Report Block . . . . . . . . . . . . . . . . . 4
4. XR Bytes Discarded Report Block . . . . . . . . . . . . . . . 5 4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 5
5. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 7 4.1. Reporting Node (Receiver) . . . . . . . . . . . . . . . . 5
5.1. Reporting Node (Receiver) . . . . . . . . . . . . . . . . 7 4.2. Media Sender . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Media Sender . . . . . . . . . . . . . . . . . . . . . . 7 5. SDP signaling . . . . . . . . . . . . . . . . . . . . . . . . 6
6. SDP signaling . . . . . . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7.1. XR Report Block Registration . . . . . . . . . . . . . . 7
8.1. XR Report Block Registration . . . . . . . . . . . . . . 8 7.2. SDP Parameter Registration . . . . . . . . . . . . . . . 7
8.2. SDP Parameter Registration . . . . . . . . . . . . . . . 8 7.3. Contact information for IANA registrations . . . . . . . 8
8.3. Contact information for IANA registrations . . . . . . . 9 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 9.1. Normative References . . . . . . . . . . . . . . . . . . 8
10.1. Normative References . . . . . . . . . . . . . . . . . . 9 9.2. Informative References . . . . . . . . . . . . . . . . . 8
10.2. Informative References . . . . . . . . . . . . . . . . . 10 Appendix A. Metrics represented using RFC6390 Template . . . . . 9
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 10 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 10
A.1. changes in draft-ietf-xrblock-rtcp-xr-discard-rle- B.1. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-00 . . . . . . . . . . . . . . . . . . . . . . . 10 metrics-00 . . . . . . . . . . . . . . . . . . . . . . . 10
A.2. changes in draft-ietf-xrblock-rtcp-xr-discard-rle- B.2. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-01 . . . . . . . . . . . . . . . . . . . . . . . 10 metrics-01 . . . . . . . . . . . . . . . . . . . . . . . 10
A.3. changes in draft-ietf-xrblock-rtcp-xr-discard-rle- B.3. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-02 . . . . . . . . . . . . . . . . . . . . . . . 10 metrics-02 . . . . . . . . . . . . . . . . . . . . . . . 10
A.4. changes in draft-ietf-xrblock-rtcp-xr-discard-rle- B.4. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-03 . . . . . . . . . . . . . . . . . . . . . . . 10 metrics-03 . . . . . . . . . . . . . . . . . . . . . . . 10
A.5. changes in draft-ietf-xrblock-rtcp-xr-discard-rle- B.5. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-04 . . . . . . . . . . . . . . . . . . . . . . . 10 metrics-04 . . . . . . . . . . . . . . . . . . . . . . . 11
A.6. changes in draft-ietf-xrblock-rtcp-xr-discard-rle- B.6. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-05 . . . . . . . . . . . . . . . . . . . . . . . 11 metrics-05 . . . . . . . . . . . . . . . . . . . . . . . 11
B.7. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-06 . . . . . . . . . . . . . . . . . . . . . . . 11
B.8. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-
metrics-07 . . . . . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
RTP [RFC3550] provides a transport for real-time media flows such as RTP [RFC3550] provides a transport for real-time media flows such as
audio and video together with the RTP control protocol (RTCP) which audio and video together with the RTP control protocol (RTCP) which
provides periodic feedback about the media streams received in a provides periodic feedback about the media streams received in a
specific duration. In addition, RTCP can be used for timely feedback specific duration. In addition, RTCP can be used for timely feedback
about individual events to report (e.g., packet loss) [RFC4585]. about individual events to report (e.g., packet loss) [RFC4585].
Both long-term and short-term feedback enable a sender to adapt its Both long-term and short-term feedback enable a media sender to adapt
media transmission and/or encoding dynamically to the observed path its media transmission and/or encoding dynamically to the observed
characteristics. path characteristics.
RFC3611 [RFC3611] defines RTCP Extended Reports as a detailed RFC3611 [RFC3611] defines RTCP Extended Reports as a detailed
reporting framework to provide more than just the coarse RR reporting framework to provide more than just the coarse Receiver
statistics. The detailed reporting may enable a sender to react more Report (RR) statistics. The detailed reporting may enable a media
appropriately to the observed networking conditions as these can be sender to react more appropriately to the observed networking
characterized better, although at the expense of extra overhead. conditions as these can be characterized better, although at the
expense of extra overhead.
Among many other report blocks, RFC3611 specifies the Loss Run Length Among many other report blocks, RFC3611 specifies the Loss Run Length
Encoding (RLE) block which reports runs of packets received and lost Encoding (RLE) block which reports runs of packets received and lost
with the granularity of individual packets. This can help both error with the granularity of individual packets. This can help both error
recovery and path loss characterization. In addition to lost recovery and path loss characterization. In addition to lost
packets, RFC3611 defines the notion of "discarded" packets: packets packets, RFC3611 defines the notion of "discarded" packets: packets
that were received but dropped from the jitter buffer because they that were received but dropped from the de-jitter buffer because they
were either too early (for buffering) or too late (for playout). The were either too early (for buffering) or too late (for playout). The
"discard rate" metric is part of the VoIP metrics report block even "discard rate" metric is part of the VoIP metrics report block even
though it is not just applicable to audio: it is specified as the though it is not just applicable to audio: it is specified as the
fraction of discarded packets since the beginning of the session. fraction of discarded packets since the beginning of the session.
See section 4.7.1 of RFC3611 [RFC3611]. See section 4.7.1 of RFC3611 [RFC3611]. The discard metric is
believed to be applicable to a large class of RTP applications which
use a de-jitter buffer RFC5481 [RFC5481].
Recently proposed extensions to the Extended Reports (XR) reporting Recently proposed extensions to the Extended Reports (XR) reporting
suggest enhancing this discard metric: suggest enhancing this discard metric:
o Reporting the number of discarded packets in a measurement o Reporting the number of discarded packets in a measurement
interval, i.e., during either the last reporting interval or since interval, i.e., during either the last reporting interval or since
the beginning of the session, as indicated by a flag in the the beginning of the session, as indicated by a flag in the
suggested XR report [I-D.ietf-xrblock-rtcp-xr-discard]. If an suggested XR report [I-D.ietf-xrblock-rtcp-xr-discard]. If an
endpoint needs to report packet discard due to other reasons than endpoint needs to report packet discard due to other reasons than
early- and late-arrival (for example, discard due to duplication, early- and late-arrival (for example, discard due to duplication,
redundancy, etc.) then it should consider using the Discarded redundancy, etc.) then it should consider using the Discarded
Packets Report Block [I-D.ietf-xrblock-rtcp-xr-discard]. Packets Report Block [I-D.ietf-xrblock-rtcp-xr-discard].
o Reporting gaps and bursts of discarded packets during a o Reporting gaps and bursts of discarded packets during a
measurement interval, i.e., the last reporting interval or the measurement interval, i.e., the last reporting interval or the
duration of the session duration of the session
[I-D.ietf-xrblock-rtcp-xr-burst-gap-discard]. [I-D.ietf-xrblock-rtcp-xr-burst-gap-discard].
o Reporting the sum of payload bytes discarded during a measurement
interval, i.e., the last reporting interval or the duration of the
session [I-D.singh-xrblock-rtcp-xr-bytes-discarded-metric].
However, none of these metrics allow a receiver to report precisely However, none of these metrics allow a receiver to report precisely
which packets were discarded. While this information could in theory which packets were discarded. While this information could in theory
be derived from high-frequency reporting on the number of discarded be derived from high-frequency reporting on the number of discarded
packets [I-D.ietf-xrblock-rtcp-xr-discard] or from the gap/burst packets [I-D.ietf-xrblock-rtcp-xr-discard] or from the gap/burst
report [I-D.ietf-xrblock-rtcp-xr-burst-gap-discard], these two report [I-D.ietf-xrblock-rtcp-xr-burst-gap-discard], these two
mechanisms do not appear feasible: The former would require an unduly mechanisms do not appear feasible: The former would require an unduly
high amount of reporting which still might not be sufficient due to high amount of reporting which still might not be sufficient due to
the non-deterministic scheduling of RTCP packets. The latter incur the non-deterministic scheduling of RTCP packets. The latter incur
significant complexity and reporting overhead and might still not significant complexity and reporting overhead and might still not
deliver the desired accuracy. deliver the desired accuracy.
This document defines a discard report block following the idea of This document defines a discard report block following the idea of
the run-length encoding applied for lost and received packets in the run-length encoding applied for lost and received packets in
[RFC3611]. [RFC3611].
Complementary to or instead of the indication which packets were
discarded, an XR block is defined to indicate the number of bytes
discarded, per interval or for the duration of the session, similar
to other XR report blocks.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in BCP 14, RFC 2119 document are to be interpreted as described in BCP 14, RFC 2119
[RFC2119] and indicate requirement levels for compliant [RFC2119].
implementations.
The terminology defined in RTP [RFC3550] and in the extensions for XR The terminology defined in RTP [RFC3550] and in the extensions for XR
reporting [RFC3611] applies. reporting [RFC3611] applies.
3. XR Discard RLE Report Block 3. XR Discard RLE Report Block
The XR Discard RLE report block uses the same format as specified for The XR Discard RLE report block uses the same format as specified for
the loss and duplicate report blocks in [RFC3611]. Figure 1 the loss and duplicate report blocks in [RFC3611]. Figure 1
describes the packet format. The fields "BT", "T", "block length", describes the packet format. The fields "BT", "T", "block length",
"SSRC of source", "begin_seq", and "end_seq" SHALL have the same "SSRC of source", "begin_seq", and "end_seq" have the same semantics
semantics and representation as defined in [RFC3611]. The "chunks" and representation as defined in [RFC3611], with the addition of the
encoding the run length SHALL have the same representation as in "E" flag to indicate the reason for discard. The "chunks" encoding
RFC3611, but encode discarded packets. the run length have the same representation as in RFC3611, but encode
discarded packets. A definition of a discarded packet is given in
[I-D.ietf-xrblock-rtcp-xr-discard].
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=DRLE |rsvd |E| T | block length | | BT=DRLE |rsvd |E| T | block length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source | | SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| begin_seq | end_seq | | begin_seq | end_seq |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| chunk 1 | chunk 2 | | chunk 1 | chunk 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... : : ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| chunk n-1 | chunk n | | chunk n-1 | chunk n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: XR Discard Report Block Figure 1: XR Discard RLE Report Block
Block Type (BT, 8 bits): A Run-length encoded Discarded Packets Block Type (BT, 8 bits): A Run-length encoded Discarded Packets
Report Block is identified by the constant DRLE. Report Block is identified by the constant DRLE.
[Note to RFC Editor: please replace DRLE with the IANA provided RTCP [Note to RFC Editor: please replace DRLE with the IANA provided RTCP
XR block type for this block. Please remove this note prior to XR block type for this block. Please remove this note prior to
publication as an RFC.] publication as an RFC.]
rsvd (3 bits): These reserved bits SHOULD be set to zero by receivers rsvd (3 bits): This field is reserved for future definition. In the
and MUST be ignored by senders. absence of such definition, the bits in this field MUST be set to
zero and MUST be ignored by the receiver.
The 'E' bit is introduced to distinguish between packets discarded The 'E' bit is introduced to distinguish between packets discarded
due to early arrival and those discarded due to late arrival. The due to early arrival and those discarded due to late arrival. The
'E' bit MUST be set to '1' if the chunks represent packets discarded 'E' bit is set to '1' if the chunks represent packets discarded due
due to too early arrival and MUST be set to '0' otherwise. to too early arrival and is set to '0' otherwise.
In case both early and late discarded packets shall be reported, two In case both early and late discarded packets shall be reported, two
Discard RLE report blocks MUST be included; their sequence number Discard RLE report blocks MUST be included; their sequence number
range MAY overlap, but individual packets MUST only be reported as range MAY overlap, but individual packets MUST only be reported as
either early or late and not appear marked in both. Packets reported either early or late and not appear marked in both. If packets
in neither are considered to be properly received and not discarded. appear in both report blocks, the conflicting packets are ignored.
Packets reported in neither are considered to be properly received
and not discarded.
Discard RLE Report Blocks SHOULD be sent in conjunction with an RTCP Discard RLE Report Blocks SHOULD be sent in conjunction with an RTCP
RR as a compound RTCP packet. RR as a compound RTCP packet.
4. XR Bytes Discarded Report Block 4. Protocol Operation
The XR Bytes Discarded report block uses the following format which
follows the model of the framework for performance metric development
[RFC6390].
0 1 2 3
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BT=BDR | I |E|reserved | block length=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| number of bytes discarded |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: XR Bytes Discarded Report Block
Block Type (BT, 8 bits): A Bytes Discarded Packets Report Block is
identified by the constant BDR.
[Note to RFC Editor: please replace BDR with the IANA provided RTCP
XR block type for this block. Please remove this note prior to
publication as an RFC.]
The Interval Metric flag (I) (2 bits) is used to indicate whether the
discard metric is Interval, or a Cumulative metric, that is, whether
the reported value applies to the most recent measurement interval
duration between successive reports (I=10, the Interval Duration) or
to the accumulation period characteristic of cumulative measurements
(I=11, the Cumulative Duration). Since the bytes discarded are not
measured at a particular time instance but over one or several
reporting intervals, the metric MUST NOT be reported as a Sampled
Metric (I=01).
The 'E' bit is introduced to distinguish between packets discarded
due to early arrival and those discarded due to late arrival. The
'E' bit MUST be set to '1' if it reports bytes discarded due to early
arrival and MUST be set to '0' if it reports bytes discarded due to
late arrival. In case both early and late discarded packets shall be
reported, two Bytes Discarded report blocks MUST be included.
These reserved bits (5 bits) SHOULD be set to zero by receivers and
MUST be ignored by senders.
block length (16 bits) MUST be set to 2, in accordance with the
definition of this field in [RFC3611]. The block MUST be discarded
if the block length is set to a different value.
The 'number of bytes discarded' is a 32-bit unsigned integer value
indicating the total number of bytes discarded.
If Interval Metric flag (I=11) is set, the value in the field
indicates the number of bytes discarded from the start of the
session, if Interval Metric flag (I=01) is set, it indicates the
number of bytes discarded since the last RTCP XR Byte Discarded Block
was received.
If the XR block follows a measurement identity block [RFC6776] in the
same RTCP compound packet then the cumulative (I=11) or the interval
(I=10) for this report block corresponds to the values of the
"measurement duration" in the measurement information block.
If the receiver sends the Bytes Discarded Report Block without the
measurement identity block then the discard block MUST be sent in
conjunction with an RTCP Receiver Report (RR) as a compound RTCP
packet.
5. Protocol Operation
This section describes the behavior of the reporting (= receiver) This section describes the behavior of the reporting node (= media
node and the media sender. receiver) and the media sender.
5.1. Reporting Node (Receiver) 4.1. Reporting Node (Receiver)
Transmission of RTCP XR Discard RLE Reports is up to the discretion Transmission of RTCP XR Discard RLE Reports is up to the discretion
of the receiver, as is the reporting granularity. However, it is of the media receiver, as is the reporting granularity. However, it
RECOMMENDED that the receiver signals all discarded packets using the is RECOMMENDED that the media receiver signals all discarded packets
method defined in this document. If all packets over a reporting using the method defined in this document. If all packets over a
period were lost, the receiver MAY use the Discard Report Block reporting period were discarded, the media receiver MAY use the
[I-D.ietf-xrblock-rtcp-xr-discard] instead. In case of limited Discard Report Block [I-D.ietf-xrblock-rtcp-xr-discard] instead. In
available reporting bandwidth, it is up to the receiver whether or case of limited available reporting bandwidth, it is up to the
not to include RTCP XR Discard RLE reports. receiver whether or not to include RTCP XR Discard RLE reports.
The receiver MAY send the Discard RLE Reports as part of the The media receiver MAY send the Discard RLE Reports as part of the
regularly scheduled RTCP packets as per RFC3550. It MAY also include regularly scheduled RTCP packets as per RFC3550. It MAY also include
Discard RLE Reports in immediate or early feedback packets as per Discard RLE Reports in immediate or early feedback packets as per
RFC4585. RFC4585.
5.2. Media Sender 4.2. Media Sender
The media sender MUST be prepared to operate without receiving any The media sender MUST be prepared to operate without receiving any
Discard RLE reports. If Discard RLE reports are generated by the Discard RLE reports. If Discard RLE reports are generated by the
receiver, the sender cannot rely on all these reports being received, media receiver, the media sender cannot rely on all these reports
nor can the sender rely on a regular generation pattern from the being received, nor can the media sender rely on a regular generation
receiver side. pattern from the media receiver.
However, if the sender receives any RTCP reports but no Discard RLE
report blocks and is aware that the receiver supports Discard RLE
report blocks, it MAY assume that no packets were discarded at the
receiver.
The sender SHOULD accept the Bytes Discarded Report Block only if it However, if the media sender receives any RTCP reports but no Discard
is received in a compound RTCP receiver report or if it is preceded RLE report blocks and is aware that the media receiver supports
by a measurement identity block [RFC6776]. Under all other Discard RLE report blocks, it MAY assume that no packets were
circumstances it MUST ignore the block. discarded at the media receiver.
6. SDP signaling 5. SDP signaling
A participant of a media session MAY use SDP to signal its support A participant of a media session MAY use SDP to signal its support
for the two report blocks specified in this document or use them for the report block specified in this document or use them without
without any prior signaling (see section 5 of [RFC3611]). any prior signaling (see section 5 of [RFC3611]).
For signaling in SDP, the RTCP XR attribute as defined in [RFC3611] For signaling in SDP, the RTCP XR attribute as defined in [RFC3611]
MUST be used. The SDP [RFC4566] attribute 'xr-format' defined in MUST be used. The SDP [RFC4566] attribute 'xr-format' defined in
RFC3611 is augmented as described in the following to indicate the RFC3611 is augmented as described in the following to indicate the
RLE discard metric and bytes discarded metric. the discard RLE metric.
rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)] rtcp-xr-attrib = "a=" "rtcp-xr" ":" [xr-format *(SP xr-format)]
CRLF ; defined in [RFC3611] CRLF ; defined in [RFC3611]
xr-format =/ xr-discard-rle xr-format =/ xr-discard-rle
/ xr-discard-bytes
xr-discard-rle = "discard-rle" xr-discard-rle = "discard-rle"
xr-discard-bytes = "discard-bytes"
The parameter 'discard-rle' MUST be used to indicate support for the The parameter 'discard-rle' is used to indicate support for the
Discard RLE Report Block defined in Section 3, the parameter Discard RLE Report Block defined in Section 3.
'discard-bytes' to indicate support for the Bytes Discarded Report
Block defined in Section 4
When SDP is used in Offer/Answer context, the mechanism defined in When SDP is used in Offer/Answer context, the mechanism defined in
[RFC3611] for unilateral "rtcp-xr" attribute parameters applies (see [RFC3611] for unilateral "rtcp-xr" attribute parameters applies (see
section 5.2 of [RFC3611]). section 5.2 of [RFC3611]).
7. Security Considerations 6. Security Considerations
The security considerations of [RFC3550], [RFC3611], and [RFC4585] The Discard RLE block provides per-packet statistics so the risk to
apply. Since this document offers only a more precise reporting for confidentiality documented in Section 7, paragraph 3 of [RFC3611]
an already existing metric, no further security implications are applies. In some situations, returning very detailed error
foreseen. information (e.g., over-range measurement or measurement unavailable)
using this report block can provide an attacker with insight into the
security processing. Implementers should consider the guidance in
[I-D.ietf-avt-srtp-not-mandatory] for using appropriate security
mechanisms, i.e., where security is a concern, the implementation
should apply encryption and authentication to the report block. For
example this can be achieved by using the AVPF profile together with
the Secure RTP profile as defined in [RFC3711]; an appropriate
combination of the two profiles (an "SAVPF") is specified in
[RFC5124]. However, other mechanisms also exist (documented in
[I-D.ietf-avtcore-rtp-security-options]) and might be more suitable.
8. IANA Considerations Additionally, The security considerations of [RFC3550], [RFC3611],
and [RFC4585] apply.
7. IANA Considerations
New block types for RTCP XR are subject to IANA registration. For New block types for RTCP XR are subject to IANA registration. For
general guidelines on IANA considerations for RTCP XR, refer to general guidelines on IANA considerations for RTCP XR, refer to
[RFC3611]. [RFC3611].
8.1. XR Report Block Registration 7.1. XR Report Block Registration
This document extends the IANA "RTP Control Protocol Extended Reports This document extends the IANA "RTP Control Protocol Extended Reports
(RTCP XR) Block Type Registry" by two new values: DRLE and BDR. (RTCP XR) Block Type Registry" by a new value: DRLE (Discard RLE
Report).
[Note to RFC Editor: please replace DRLE and BDR with the IANA [Note to RFC Editor: please replace DRLE with the IANA provided RTCP
provided RTCP XR block type for this block here and in the diagrams XR block type for this block here and in the diagrams above. Please
above. Please remove this note prior to publication as an RFC.] remove this note prior to publication as an RFC.]
8.2. SDP Parameter Registration 7.2. SDP Parameter Registration
This document registers two new parameters for the Session
Description Protocol (SDP), "discard-rle" and "discard-bytes", in the
"RTP Control Protocol Extended Reports (RTCP XR) Session Description
Protocol (SDP) Parameters Registry".
8.3. Contact information for IANA registrations This document registers a new parameters for the Session Description
Protocol (SDP), "discard-rle" in the "RTP Control Protocol Extended
Reports (RTCP XR) Session Description Protocol (SDP) Parameters
Registry".
7.3. Contact information for IANA registrations
Joerg Ott (jo@comnet.tkk.fi) Joerg Ott (jo@comnet.tkk.fi)
Aalto University Comnet, Otakaari 5A, 02150 Espoo, Finland. Aalto University Comnet, Otakaari 5A, 02150 Espoo, Finland.
9. Acknowledgments 8. Acknowledgments
Thanks to Qin Wu, Colin Perkins, Dan Romascanu, Roni Even and Dan The authors would like to thank Alan Clark, Roni Even, Sam Hartman,
Wing for providing valuable feedback on earlier versions of this Colin Perkins, Dan Romascanu, Dan Wing, and Qin Wu for providing
draft valuable feedback on earlier versions of this draft.
10. References 9. References
10.1. Normative References 9.1. 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.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, July 2003. Applications", STD 64, RFC 3550, July 2003.
[RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control [RFC3611] Friedman, T., Caceres, R., and A. Clark, "RTP Control
Protocol Extended Reports (RTCP XR)", RFC 3611, November Protocol Extended Reports (RTCP XR)", RFC 3611, November
2003. 2003.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control "Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July
2006. 2006.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New
Performance Metric Development", BCP 170, RFC 6390,
October 2011.
[RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information
Reporting Using a Source Description (SDES) Item and an
RTCP Extended Report (XR) Block", RFC 6776, October 2012.
10.2. Informative References
[I-D.ietf-xrblock-rtcp-xr-discard] [I-D.ietf-xrblock-rtcp-xr-discard]
Clark, A., Zorn, G., and W. Wu, "RTP Control Protocol Clark, A., Zorn, G., and W. Wu, "RTP Control Protocol
(RTCP) Extended Report (XR) Block for Discard Count metric (RTCP) Extended Report (XR) Block for Discard Count metric
Reporting", draft-ietf-xrblock-rtcp-xr-discard-15 (work in Reporting", draft-ietf-xrblock-rtcp-xr-discard-15 (work in
progress), June 2013. progress), June 2013.
9.2. Informative References
[I-D.ietf-xrblock-rtcp-xr-burst-gap-discard] [I-D.ietf-xrblock-rtcp-xr-burst-gap-discard]
Clark, A., Huang, R., and W. Wu, "RTP Control Clark, A., Huang, R., and W. Wu, "RTP Control
Protocol(RTCP) Extended Report (XR) Block for Burst/Gap Protocol(RTCP) Extended Report (XR) Block for Burst/Gap
Discard metric Reporting", draft-ietf-xrblock-rtcp-xr- Discard metric Reporting", draft-ietf-xrblock-rtcp-xr-
burst-gap-discard-14 (work in progress), April 2013. burst-gap-discard-14 (work in progress), April 2013.
Appendix A. Change Log [RFC5481] Morton, A. and B. Claise, "Packet Delay Variation
Applicability Statement", RFC 5481, March 2009.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, February 2008.
[I-D.ietf-avt-srtp-not-mandatory]
Perkins, C. and M. Westerlund, "Securing the RTP Protocol
Framework: Why RTP Does Not Mandate a Single Media
Security Solution", draft-ietf-avt-srtp-not-mandatory-13
(work in progress), May 2013.
[I-D.ietf-avtcore-rtp-security-options]
Westerlund, M. and C. Perkins, "Options for Securing RTP
Sessions", draft-ietf-avtcore-rtp-security-options-04
(work in progress), July 2013.
[I-D.singh-xrblock-rtcp-xr-bytes-discarded-metric]
Singh, V., Ott, J., and I. Curcio, "RTP Control Protocol
(RTCP) Extended Reports (XR) for Bytes Discarded Metric",
draft-singh-xrblock-rtcp-xr-bytes-discarded-metric-00
(work in progress), August 2013.
Appendix A. Metrics represented using RFC6390 Template
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC
number, when assigned.
a. Run-length encoding (RLE) of Discarded Packets Metric
* Metric Name: Discard Run-length encoding Metric
* Metric Description: Instances of packets discarded over the
period covered by this report.
* Method of Measurement or Calculation: See section 3, for the
definition of Discard RLE [RFCXXXX] and section 4.1 of RFC3611
for Run-length encoding.
* Units of Measurement: Every packet in the interval is reported
as discarded or not. See section 3 for the definition of
Discard RLE [RFCXXXX].
* Measurement Point(s) with Potential Measurement Domain: The
measurement of these metrics is made at the receiving end of
the RTP stream.
* Measurement Timing: Each packet between a beginning sequence
number (begin_seq) and ending sequence number (end_seq) are
reported as discarded or not. See section 3 for the
definition of Discard RLE [RFCXXXX].
* Use and applications: See section 1, paragraph 1 of [RFCXXXX].
* Reporting model: See RFC3611.
Appendix B. Change Log
Note to the RFC-Editor: please remove this section prior to Note to the RFC-Editor: please remove this section prior to
publication as an RFC. publication as an RFC.
A.1. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-00 B.1. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-00
o Changed the interval flag from 1 to 2 bits in the discarded bytes o Changed the interval flag from 1 to 2 bits in the discarded bytes
report. Also added the measurement identification tag to the report. Also added the measurement identification tag to the
block. block.
o Added this section. o Added this section.
A.2. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-01 B.2. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-01
o Removed the measurement identification tag in the bytes discarded o Removed the measurement identification tag in the bytes discarded
block. block.
A.3. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-02 B.3. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-02
o Removed the extra Tag bits from the Discarded bytes XR block. o Removed the extra Tag bits from the Discarded bytes XR block.
o Clarified use of measurement identity block in Section 4 and 5.2 o Clarified use of measurement identity block in Section 4 and 5.2
A.4. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-03 B.4. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-03
o Added explanation for block length in bytes discarded block. o Added explanation for block length in bytes discarded block.
o Added an acknowledgement section. o Added an acknowledgement section.
A.5. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-04 B.5. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-04
o Added Block Type definition to each XRBlock. o Added Block Type definition to each XRBlock.
o Made changes requested in WGLC. o Made changes requested in WGLC.
A.6. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-05 B.6. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-05
o Made changes requested by SDP directorate. o Made changes requested by SDP directorate.
B.7. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-06
o Editorial fixes based on review from Gen-art and IESG review.
B.8. changes in draft-ietf-xrblock-rtcp-xr-discard-rle-metrics-07
o Editorial fixes based on review from IESG.
o Editorial fixes based on Security and PM directorate.
o Split bytes discarded from this draft to another.
o Updated Security Considerations Section.
o This draft now normatively cites the definition of discards in
'packets discarded' draft.
Authors' Addresses Authors' Addresses
Joerg Ott Joerg Ott
Aalto University Aalto University
School of Electrical Engineering School of Electrical Engineering
Otakaari 5 A Otakaari 5 A
Espoo, FIN 02150 Espoo, FIN 02150
Finland Finland
Email: jo@comnet.tkk.fi Email: jo@comnet.tkk.fi
Varun Singh Varun Singh (editor)
Aalto University Aalto University
School of Electrical Engineering School of Electrical Engineering
Otakaari 5 A Otakaari 5 A
Espoo, FIN 02150 Espoo, FIN 02150
Finland Finland
Email: varun@comnet.tkk.fi Email: varun@comnet.tkk.fi
URI: http://www.netlab.tkk.fi/~varun/ URI: http://www.netlab.tkk.fi/~varun/
Igor D.D. Curcio Igor D.D. Curcio
Nokia Research Center Nokia Research Center
P.O. Box 1000 (Visiokatu 3) P.O. Box 1000 (Visiokatu 3)
Tampere, FIN 33721 Tampere, FIN 33721
Finland Finland
Email: igor.curcio@nokia.com Email: igor.curcio@nokia.com
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