draft-ietf-xrblock-rtcp-xr-bytes-discarded-metric-02.txt   rfc7243.txt 
XR Block Working Group V. Singh, Ed. Internet Engineering Task Force (IETF) V. Singh, Ed.
Internet-Draft J. Ott Request for Comments: 7243 J. Ott
Intended status: Standards Track Aalto University Category: Standards Track Aalto University
Expires: August 30, 2014 I. Curcio ISSN: 2070-1721 I. Curcio
Nokia Research Center Nokia Research Center
February 26, 2014 May 2014
RTP Control Protocol (RTCP) Extended Report (XR) for Bytes Discarded RTP Control Protocol (RTCP) Extended Report (XR) Block
Metric for the Bytes Discarded Metric
draft-ietf-xrblock-rtcp-xr-bytes-discarded-metric-02
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) to provide a variety of short-term and
and long-term reception statistics. The available reporting may long-term reception statistics. The available reporting may include
include aggregate information across longer periods of time as well aggregate information across longer periods of time as well as
as individual packet reporting. This document specifies a report individual packet reporting. This document specifies a report
computing the bytes discarded from the de-jitter buffer after computing the bytes discarded from the de-jitter buffer after
successful reception. successful reception.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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 August 30, 2014. 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/rfc7243.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction ....................................................3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology .....................................................4
3. XR Bytes Discarded Report Block . . . . . . . . . . . . . . . 4 3. Bytes Discarded Report Block ....................................4
4. Protocol Operation . . . . . . . . . . . . . . . . . . . . . 5 4. Protocol Operation ..............................................6
4.1. Reporting Node (Receiver) . . . . . . . . . . . . . . . . 5 4.1. Reporting Node (Receiver) ..................................6
4.2. Media Sender . . . . . . . . . . . . . . . . . . . . . . 6 4.2. Media Sender ...............................................6
5. SDP signaling . . . . . . . . . . . . . . . . . . . . . . . . 6 5. SDP Signaling ...................................................7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Security Considerations .........................................7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations .............................................8
7.1. XR Report Block Registration . . . . . . . . . . . . . . 8 7.1. XR Report Block Registration ...............................8
7.2. SDP Parameter Registration . . . . . . . . . . . . . . . 8 7.2. SDP Parameter Registration .................................8
7.3. Contact information for IANA registrations . . . . . . . 8 7.3. Contact Information for IANA Registrations .................8
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 8. Acknowledgments .................................................8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 9. References ......................................................9
9.1. Normative References . . . . . . . . . . . . . . . . . . 8 9.1. Normative References .......................................9
9.2. Informative References . . . . . . . . . . . . . . . . . 9 9.2. Informative References .....................................9
Appendix A. Metrics represented using RFC6390 Template . . . . . 10 Appendix A. Metrics Represented Using the Template from RFC 6390 ..11
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 10
B.1. changes in draft-singh-xrblock-rtcp-xr-bytes-
discarded-metric-01 . . . . . . . . . . . . . . . . . . . 10
B.2. changes in draft-singh-xrblock-rtcp-xr-bytes-
discarded-metric-00 . . . . . . . . . . . . . . . . . . . 11
B.3. changes in draft-ietf-xrblock-rtcp-xr-bytes-
discarded-metric-00 . . . . . . . . . . . . . . . . . . . 11
B.4. changes in draft-ietf-xrblock-rtcp-xr-bytes-
discarded-metric-01 . . . . . . . . . . . . . . . . . . . 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 media sender to adapt Both long-term and short-term feedback enable a media sender to adapt
its media transmission and/or encoding dynamically to the observed its media transmission and/or encoding dynamically to the observed
path characteristics. path characteristics.
[RFC3611] defines RTCP Extended Reports as a detailed reporting [RFC3611] defines RTCP Extended Reports as a detailed reporting
framework to provide more than just the coarse Receiver Report (RR) framework to provide more than just the coarse Receiver Report (RR)
statistics. The detailed reporting may enable a media sender to statistics. The detailed reporting may enable a media sender to
react more appropriately to the observed networking conditions as react more appropriately to the observed networking conditions as
these can be characterized better, although at the expense of extra these can be characterized better, although at the expense of extra
overhead. overhead.
In addition to lost packets, [RFC3611] defines the notion of In addition to lost packets, [RFC3611] defines the notion of
"discarded" packets: packets that were received but dropped from the "discarded" packets: packets that were received but dropped from the
de-jitter buffer because they were either too early (for buffering) de-jitter buffer because they were either too early (for buffering)
or too late (for playout). The "discard rate" metric is part of the or too late (for playout). The "discard rate" metric is part of the
VoIP metrics report block even though it is not just applicable to VoIP metrics report block even though it is not just applicable to
audio: it is specified as the fraction of discarded packets since the audio: it is specified as the fraction of discarded packets since the
beginning of the session. See section 4.7.1 of [RFC3611]. The beginning of the session. See Section 4.7.1 of [RFC3611]. The
discard metric is believed to be applicable to a large class of RTP discard metric is believed to be applicable to a large class of RTP
applications which use a de-jitter buffer [RFC5481]. applications that use a de-jitter buffer [RFC5481].
Recently proposed extensions to the Extended Reports (XR) reporting Recently proposed extensions to the Extended Reports (XR) reporting
suggest enhancing the discard metric: suggest enhancing the 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 [RFC7002]. If an endpoint needs to report suggested XR report [RFC7002]. If an endpoint needs to report
packet discard due to other reasons than early- and late-arrival packet discard due to other reasons than early- and late-arrival
(for example, discard due to duplication, redundancy, etc.) then (for example, discard due to duplication, redundancy, etc.) then
it should consider using the Discarded Packets Report Block it should consider using the Discarded Packets Report Block
[RFC7002]. [RFC7002].
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 [RFC7003]. duration of the session [RFC7003].
o Reporting run-length encoding of discarded packet during a o Reporting run-length encoding of a discarded packet during a
measurement interval, i.e., between a set of sequence numbers measurement interval, i.e., between a set of sequence numbers
[RFC7097]. [RFC7097].
However, none of these metrics allow a receiver to report precisely However, none of these metrics allow a receiver to report precisely
the number of RTP payload bytes that were discarded. While this the number of RTP payload bytes that were discarded. While this
information could in theory be derived from high-frequency reporting information could in theory be derived from high-frequency reporting
on the number of discarded packets [RFC7002] or from the Discard RLE on the number of discarded packets [RFC7002] or from the Discard RLE
report [RFC7097], these two mechanisms do not appear feasible; the (Run Length Encoding) report [RFC7097], these two mechanisms do not
former would require an unduly high amount of reporting which still appear feasible. The former would require an unduly high amount of
might not be sufficient due to the non-deterministic scheduling of reporting that still might not be sufficient due to the non-
RTCP packets. The latter incurs significant complexity (by storing a deterministic scheduling of RTCP packets. The latter incurs
map of sequence numbers and packet sizes) and reporting overhead. significant complexity (by storing a map of sequence numbers and
packet sizes) and reporting overhead.
An XR block is defined in this document to indicate the number of RTP An XR block is defined in this document to indicate the number of RTP
payload bytes discarded, per interval or for the duration of the payload bytes discarded, per interval or for the duration of the
session, similar to the other XR report blocks. session, similar to the other XR 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, [RFC2119]. document are to be interpreted as described in BCP 14, [RFC2119].
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 Bytes Discarded Report Block 3. Bytes Discarded Report Block
The XR Bytes Discarded report block uses the following format which The Bytes Discarded Report Block uses the following format, which
follows the model of the framework for performance metric development follows the model of the framework for performance metric development
[RFC6390]. [RFC6390].
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=BDR | I |E|reserved | block length=2 | | BT=26 | I |E|Reserved | Block length=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC of source | | SSRC of source |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| number of RTP payload bytes discarded | | Number of RTP payload bytes discarded |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: XR Bytes Discarded Report Block Figure 1: XR Bytes Discarded Report Block
Block Type (BT, 8 bits): A Bytes Discarded Packets Report Block is Block Type (BT): 8 bits. A Bytes Discarded Packets Report Block is
identified by the constant BDR. identified by the constant 26.
[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 Interval Metric flag (I): 2 bits. It is used to indicate whether the
discard metric is Interval, or a Cumulative metric, that is, whether discard metric is an Interval or a Cumulative metric, that is,
the reported value applies to the most recent measurement interval whether the reported value applies to the most recent measurement
duration between successive reports (I=10, the Interval Duration) or interval duration between successive reports (I=10, the Interval
to the accumulation period characteristic of cumulative measurements Duration) or to the accumulation period characteristic of cumulative
(I=11, the Cumulative Duration). Since the bytes discarded are not measurements (I=11, the Cumulative Duration). Since the bytes
measured at a particular time instance but over one or several discarded are not measured at a particular time instance but over one
reporting intervals, the metric MUST NOT be reported as a Sampled or several reporting intervals, the metric MUST NOT be reported as a
Metric (I=01). In addition, the value I=00 is reserved and MUST NOT Sampled Metric (I=01). In addition, the value I=00 is reserved and
be sent, and MUST be discarded when received. MUST NOT be sent, and it MUST be discarded when received.
The 'E' bit is introduced to distinguish between packets discarded Early bit (E): It is introduced to distinguish between packets
due to early arrival and those discarded due to late arrival. The discarded due to early arrival and those discarded due to late
'E' bit is set to '1' if it reports bytes discarded due to early arrival. The E bit is set to '1' if it reports bytes discarded due
arrival and is set to '0' if it reports bytes discarded due to late to early arrival and is set to '0' if it reports bytes discarded due
arrival. If a duplicate packet is received and discarded, these to late arrival. If a duplicate packet is received and discarded,
duplicate packets are ignored and not reported. In case both early these duplicate packets are ignored and not reported. In case both
and late discarded packets shall be reported, two Bytes Discarded early and late discarded packets shall be reported, two Bytes
report blocks MUST be included. Discarded report blocks MUST be included.
reserved (5 bits): This field is reserved for future definition. In Reserved: 5 bits. This field is reserved for future definition. In
the absence of such definition, the bits in this field MUST be set to the absence of such definition, the bits in this field MUST be set to
zero and MUST be ignored by the receiver. zero and MUST be ignored by the receiver.
block length (16 bits) MUST be set to 2, in accordance with the Block length: 16 bits. It MUST be set to 2, in accordance with the
definition of this field in [RFC3611]. The block MUST be discarded definition of this field in [RFC3611]. The block MUST be discarded
if the block length is set to a different value. if the block length is set to a different value.
The 'number of RTP payload bytes discarded' is a 32-bit unsigned Number of RTP payload bytes discarded: It is a 32-bit unsigned
integer value indicating the total number of bytes discarded. Bytes integer value indicating the total number of bytes discarded. The
discarded corresponds to the RTP payload size of every RTP packet 'bytes discarded' corresponds to the RTP payload size of every RTP
that is discarded (due to early or late arrival). Hence, the bytes packet that is discarded (due to early or late arrival). Hence, the
discarded ignores the size of any RTP header extensions and the size 'bytes discarded' ignores the size of any RTP header extensions and
of the padding bits. Also the discarded packet is associated to the the size of the padding bits. Also the discarded packet is
interval in which it was discarded and not when it was expected. associated to the interval in which it was discarded, not when it was
expected.
If Interval Metric flag (I=11) is set, the value in the field If the Interval Metric flag is set as I=11, the value in the field
indicates the number of RTP payload bytes discarded from the start of indicates the number of RTP payload bytes discarded from the start of
the session, if Interval Metric flag (I=10) is set, it indicates the the session; if the Interval Metric flag is set as I=10, it indicates
number of bytes discarded in the most recent reporting interval. the number of bytes discarded in the most recent reporting interval.
If the XR block follows a measurement identity block [RFC6776] in the If the XR block follows a Measurement Information Block [RFC6776] in
same RTCP compound packet then the cumulative (I=11) or the interval the same RTCP compound packet, then the cumulative (I=11) or the
(I=10) for this report block corresponds to the values of the interval (I=10) for this report block corresponds to the values of
"measurement duration" in the measurement information block. the "measurement duration" in the Measurement Information Block.
If the receiver sends the Bytes Discarded Report Block without the If the receiver sends the Bytes Discarded Report Block without the
measurement identity block then the discard block MUST be sent in Measurement Information Block, then the Bytes Discarded Report Block
conjunction with an RTCP Receiver Report (RR) as a compound RTCP MUST be sent in conjunction with an RTCP Receiver Report (RR) as a
packet. compound RTCP packet.
4. Protocol Operation 4. Protocol Operation
This section describes the behavior of the reporting node (= media This section describes the behavior of the reporting node (i.e., the
receiver) and the media sender. media receiver) and the media sender.
4.1. Reporting Node (Receiver) 4.1. Reporting Node (Receiver)
The media receiver MAY send the Bytes Discard Reports as part of the
regularly scheduled RTCP packets as per RFC3550. It MAY also include
Bytes Discard Reports in immediate or early feedback packets as per
[RFC4585].
Transmission of RTCP XR Bytes Discarded Report is up to the The media receiver MAY send the Bytes Discarded Reports as part of
the regularly scheduled RTCP packets as per RFC 3550. It MAY also
include Bytes Discarded Reports in immediate or early feedback
packets as per [RFC4585].
Transmission of the RTCP XR Bytes Discarded Report is up to the
discretion of the media receiver, as is the reporting granularity. discretion of the media receiver, as is the reporting granularity.
However, it is RECOMMENDED that the media receiver signals the bytes However, it is RECOMMENDED that the media receiver signals the bytes
discarded packets using the method defined in this document. When discarded packets using the method defined in this document. When
reporting several metrics in a single RTCP packet, the reporting reporting several metrics in a single RTCP packet, the reporting
intervals for the report blocks are synchronized, therefore the media intervals for the report blocks are synchronized, therefore the media
receiver may choose to additionally send the Discarded Packets receiver may choose to additionally send the Discarded Packets
[RFC7002] or Discard RLE [RFC7097] Report Block to assist the media [RFC7002] or Discard RLE [RFC7097] Report Block to assist the media
sender in correlating the bytes discarded to the packets discarded in sender in correlating the bytes discarded to the packets discarded in
that particular interval. that particular interval.
skipping to change at page 6, line 33 skipping to change at page 6, line 41
4.2. 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
Bytes Discarded reports. If Bytes Discarded reports are generated by Bytes Discarded reports. If Bytes Discarded reports are generated by
the media receiver, the media sender cannot rely on all these reports the media receiver, the media sender cannot rely on all these reports
being received, nor can the media sender rely on a regular generation being received, nor can the media sender rely on a regular generation
pattern from the media receiver. pattern from the media receiver.
However, if the media sender receives any RTCP reports but no Bytes However, if the media sender receives any RTCP reports but no Bytes
Discard report blocks and is aware that the media receiver supports Discarded report blocks and is aware that the media receiver supports
Bytes Discard report blocks, it MAY assume that no packets were Bytes Discarded report blocks, it MAY assume that no packets were
discarded by the media receiver. discarded by the media receiver.
The media sender SHOULD accept the Bytes Discarded Report Block only The media sender SHOULD accept the Bytes Discarded Report Block only
if it is received in a compound RTCP receiver report or if it is if it is received in a compound RTCP receiver report or if it is
preceded by a measurement identity block [RFC6776]. Under all other preceded by a Measurement Information Block [RFC6776]. Under all
circumstances it MUST ignore the block. other circumstances, it MUST ignore the block.
5. 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 report block specified in this document or use them without for the report block specified in this document or use them 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 RFC
RFC3611 is augmented as described in the following to indicate the 3611 is augmented to indicate the Bytes Discarded metric. This is
bytes discarded metric. described in the following ABNF [RFC5234]:
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-bytes xr-format =/ xr-discard-bytes
xr-discard-bytes = "discard-bytes" xr-discard-bytes = "discard-bytes"
The parameter 'discard-bytes' to indicate support for the Bytes The parameter 'discard-bytes' to indicate support for the Bytes
Discarded Report Block defined in Section 3. Discarded Report Block is defined in Section 3.
When SDP is used in Offer/Answer context, the mechanism defined in When SDP is used in the offer/answer context, the mechanism defined
[RFC3611] for unilateral "rtcp-xr" attribute parameters applies (see in [RFC3611] for unilateral "rtcp-xr" attribute parameters applies
section 5.2 of [RFC3611]). (see Section 5.2 of [RFC3611]).
6. Security Considerations 6. Security Considerations
The Bytes Discarded block does not provide per-packet statistics, The Bytes Discarded block does not provide per-packet statistics,
hence the risk to confidentiality documented in Section 7, paragraph hence the risk to confidentiality documented in Section 7, paragraph
3 of [RFC3611] does not apply. In some situations, returning very 3 of [RFC3611] does not apply. In some situations, returning very
detailed error information (e.g., over-range measurement or detailed error information (e.g., over-range measurement or
measurement unavailable) using this report block can provide an measurement unavailable) using this report block can provide an
attacker with insight into the security processing. For example, attacker with insight into the security processing. For example,
assume that the attacker sends a packet with a stale timestamp (i.e., assume that the attacker sends a packet with a stale timestamp (i.e.,
time in the past) to the receiver. If the receiver now sends a time in the past) to the receiver. If the receiver now sends a
discard report with the same number of bytes as the payload of the discard report with the same number of bytes as the payload of the
injected packet, the attacker can infer that no security processing injected packet, the attacker can infer that no security processing
was performed. If, on the other hand, the attacker does not receive was performed. If, on the other hand, the attacker does not receive
a discard report, it can equivalently assume that the security a discard report, it can equivalently assume that the security
procedures were performed on the packet. procedures were performed on the packet.
Implementers should therefore consider the guidance in Implementers should therefore consider the guidance in [RFC7202] for
[I-D.ietf-avt-srtp-not-mandatory] for using appropriate security using appropriate security mechanisms, i.e., where security is a
mechanisms, i.e., where security is a concern, the implementation concern, the implementation should apply encryption and
should apply encryption and authentication to the report block. For authentication to the report block. For example, this can be
example this can be achieved by using the AVPF profile together with achieved by using the AVPF profile together with the Secure RTP
the Secure RTP profile as defined in [RFC3711]; an appropriate profile as defined in [RFC3711]; an appropriate combination of the
combination of the two profiles (an "SAVPF") is specified in two profiles (an "SAVPF") is specified in [RFC5124]. However, other
[RFC5124]. However, other mechanisms also exist (documented in mechanisms also exist (documented in [RFC7201]) and might be more
[I-D.ietf-avtcore-rtp-security-options]) and might be more suitable. suitable.
The discarded bytes report is employed by the sender to perform The Bytes Discarded report is employed by the sender to perform
congestion control, typically, for calculating goodput. In these congestion control, typically, for calculating goodput (i.e.,
cases an attacker MAY drive the endpoint to lower its sending rate throughput that is useful). In these cases, an attacker MAY drive
and under-utilised the link, therefore media senders should choose the endpoint to lower its sending rate and under-utilize the link;
appropriate security measures to mitigate such attacks. therefore, media senders should choose appropriate security measures
to mitigate such attacks.
Lastly, the security considerations of [RFC3550], [RFC3611], and Lastly, the security considerations of [RFC3550], [RFC3611], and
[RFC4585] apply. [RFC4585] apply.
7. IANA Considerations 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].
7.1. XR Report Block Registration 7.1. XR Block Registration
This document extends the IANA "RTP Control Protocol Extended Reports
(RTCP XR) Block Type Registry" by a new value: BDR (Bytes Discarded
Report).
[Note to RFC Editor: please replace BDR with the IANA provided RTCP This document registers a new value in the IANA "RTP Control Protocol
XR block type for this block here and in the diagrams above. Please Extended Reports (RTCP XR) Block Type Registry": 26 for BDR (Bytes
remove this note prior to publication as an RFC.] Discarded Report).
7.2. SDP Parameter Registration 7.2. SDP Parameter Registration
This document registers a new parameters for the Session Description This document registers a new parameter for the Session Description
Protocol (SDP), "discard-bytes" in the "RTP Control Protocol Extended Protocol (SDP), "discard-bytes" in the "RTP Control Protocol Extended
Reports (RTCP XR) Session Description Protocol (SDP) Parameters Reports (RTCP XR) Session Description Protocol (SDP) Parameters
Registry". Registry".
7.3. Contact information for IANA registrations 7.3. Contact Information for IANA Registrations
RAI Area Directors: rai-ads@tools.ietf.org RAI Area Directors <rai-ads@tools.ietf.org>
8. Acknowledgments 8. Acknowledgments
The authors would like to thank Alan Clark, Benoit Claise, Roni Even, The authors would like to thank Benoit Claise, Alan Clark, Roni Even,
Vijay Gurbani, Sam Hartman, Vinayak Hegde, Jeffrey Hutzelman, Barry Vijay Gurbani, Sam Hartman, Vinayak Hegde, Jeffrey Hutzelman, Barry
Leiba, Colin Perkins, Dan Romascanu, Dan Wing, and Qin Wu for Leiba, Colin Perkins, Dan Romascanu, Dan Wing, and Qin Wu for
providing valuable feedback on earlier versions of this draft. providing valuable feedback on this document during its development.
9. References 9. References
9.1. 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.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006.
[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 [RFC5234] Crocker, D., Ed., and P. Overell, "Augmented BNF for
Description Protocol", RFC 4566, July 2006. Syntax Specifications: ABNF", STD 68, RFC 5234, January
2008.
[RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New [RFC6390] Clark, A. and B. Claise, "Guidelines for Considering New
Performance Metric Development", BCP 170, RFC 6390, Performance Metric Development", BCP 170, RFC 6390,
October 2011. October 2011.
[RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information [RFC6776] Clark, A. and Q. Wu, "Measurement Identity and Information
Reporting Using a Source Description (SDES) Item and an Reporting Using a Source Description (SDES) Item and an
RTCP Extended Report (XR) Block", RFC 6776, October 2012. RTCP Extended Report (XR) Block", RFC 6776, October 2012.
[RFC7002] Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol [RFC7002] Clark, A., Zorn, G., and Q. Wu, "RTP Control Protocol
(RTCP) Extended Report (XR) Block for Discard Count Metric (RTCP) Extended Report (XR) Block for Discard Count Metric
Reporting", RFC 7002, September 2013. Reporting", RFC 7002, September 2013.
9.2. Informative References 9.2. Informative References
[RFC7003] Clark, A., Huang, R., and Q. Wu, "RTP Control Protocol
(RTCP) Extended Report (XR) Block for Burst/Gap Discard
Metric Reporting", RFC 7003, September 2013.
[RFC7097] Ott, J., Singh, V., and I. Curcio, "RTP Control Protocol
(RTCP) Extended Report (XR) for RLE of Discarded Packets",
RFC 7097, January 2014.
[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. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
RFC 3711, March 2004. RFC 3711, March 2004.
[RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for [RFC5124] Ott, J. and E. Carrara, "Extended Secure RTP Profile for
Real-time Transport Control Protocol (RTCP)-Based Feedback Real-time Transport Control Protocol (RTCP)-Based Feedback
(RTP/SAVPF)", RFC 5124, February 2008. (RTP/SAVPF)", RFC 5124, February 2008.
[I-D.ietf-avt-srtp-not-mandatory] [RFC5481] Morton, A. and B. Claise, "Packet Delay Variation
Perkins, C. and M. Westerlund, "Securing the RTP Protocol Applicability Statement", RFC 5481, March 2009.
Framework: Why RTP Does Not Mandate a Single Media
Security Solution", draft-ietf-avt-srtp-not-mandatory-16
(work in progress), January 2014.
[I-D.ietf-avtcore-rtp-security-options] [RFC7003] Clark, A., Huang, R., and Q. Wu, "RTP Control Protocol
Westerlund, M. and C. Perkins, "Options for Securing RTP (RTCP) Extended Report (XR) Block for Burst/Gap Discard
Sessions", draft-ietf-avtcore-rtp-security-options-10 Metric Reporting", RFC 7003, September 2013.
(work in progress), January 2014.
Appendix A. Metrics represented using RFC6390 Template [RFC7097] Ott, J., Singh, V., and I. Curcio, "RTP Control Protocol
(RTCP) Extended Report (XR) for RLE of Discarded Packets",
RFC 7097, January 2014.
RFC EDITOR NOTE: please change XXXX in [RFCXXXX] by the new RFC [RFC7201] Westerlund, M. and C. Perkins, "Options for Securing RTP
number, when assigned. Sessions", RFC 7201, April 2014.
[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
Framework: Why RTP Does Not Mandate a Single Media
Security Solution", RFC 7202, April 2014.
Appendix A. Metrics Represented Using the Template from RFC 6390
a. RTP Payload Bytes Discarded Metric a. RTP Payload Bytes Discarded Metric
* Metric Name: RTP Payload Bytes Discarded Metric * Metric Name: RTP Payload Bytes Discarded Metric
* Metric Description: Total number of RTP Payload bytes * Metric Description: Total number of RTP payload bytes
discarded over the period covered by this report. discarded over the period covered by this report.
* Method of Measurement or Calculation: See section 4, number of * Method of Measurement or Calculation: See the definition of
bytes discarded definition in [RFCXXXX]. "Number of RTP payload bytes discarded" in Section 3.
* Units of Measurement: See section 4, number of RTP payload * Units of Measurement: See the definition of "Number of RTP
bytes discarded definition in [RFCXXXX]. payload bytes discarded" in Section 3.
* Measurement Point(s) with Potential Measurement Domain: See * Measurement Point(s) with Potential Measurement Domain: See
section 4, 1st paragraph of [RFCXXXX]. the first paragraph of Section 3.
* Measurement Timing: See section 4, last three paragraphs of
[RFCXXXX] for measurement timing and for the Interval Metric
flag.
* 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
publication as an RFC.
B.1. changes in draft-singh-xrblock-rtcp-xr-bytes-discarded-metric-01
o Address SEC-DIR and Gen-art review.
o Incorporate IESG comments.
B.2. changes in draft-singh-xrblock-rtcp-xr-bytes-discarded-metric-00
o Bytes discarded metric split from [I-D.ietf-xrblock-rtcp-xr-
discard-rle-metrics] />.
B.3. changes in draft-ietf-xrblock-rtcp-xr-bytes-discarded-metric-00
o Submitted as a WG draft.
B.4. changes in draft-ietf-xrblock-rtcp-xr-bytes-discarded-metric-01
o Editorial fixes: Updated references from drafts to RFCs. * Measurement Timing: See the last three paragraphs of Section 3
for measurement timing and for the Interval Metric flag.
o Updated fields in the RFC6390 template. * Use and applications: See the third paragraph of Section 1.
o Changed 'number of bytes discarded' to 'number of RTP payload * Reporting model: See RFC 3611.
bytes discarded'.
Authors' Addresses Authors' Addresses
Varun Singh (editor) 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/
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
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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