draft-ietf-siprec-protocol-10.txt   draft-ietf-siprec-protocol-11.txt 
SIPREC L.P. Portman SIPREC L. Portman
Internet-Draft NICE Systems Internet-Draft NICE Systems
Intended status: Standards Track H. Lum, Ed. Intended status: Standards Track H. Lum, Ed.
Expires: November 18, 2013 Genesys Expires: April 20, 2014 Genesys
C. Eckel C. Eckel
Cisco Cisco
A. Johnston A. Johnston
Avaya Avaya
A. Hutton A. Hutton
Siemens Enterprise Communications Unify
May 17, 2013 October 17, 2013
Session Recording Protocol Session Recording Protocol
draft-ietf-siprec-protocol-10 draft-ietf-siprec-protocol-11
Abstract Abstract
This document specifies the use of the Session Initiation Protocol This document specifies the use of the Session Initiation Protocol
(SIP), the Session Description Protocol (SDP), and the Real Time (SIP), the Session Description Protocol (SDP), and the Real Time
Protocol (RTP) for delivering real-time media and metadata from a Protocol (RTP) for delivering real-time media and metadata from a
Communication Session (CS) to a recording device. The Session Communication Session (CS) to a recording device. The Session
Recording Protocol specifies the use of SIP, SDP, and RTP to Recording Protocol specifies the use of SIP, SDP, and RTP to
establish a Recording Session (RS) between the Session Recording establish a Recording Session (RS) between the Session Recording
Client (SRC), which is on the path of the CS, and a Session Recording Client (SRC), which is on the path of the CS, and a Session Recording
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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 November 18, 2013. This Internet-Draft will expire on April 20, 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.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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6.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 10 6.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 10
6.3. Procedures for Recording-aware User Agents . . . . . . . 11 6.3. Procedures for Recording-aware User Agents . . . . . . . 11
7. SDP Handling . . . . . . . . . . . . . . . . . . . . . . . . 11 7. SDP Handling . . . . . . . . . . . . . . . . . . . . . . . . 11
7.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 12 7.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 12
7.1.1. SDP handling in RS . . . . . . . . . . . . . . . . . 12 7.1.1. SDP handling in RS . . . . . . . . . . . . . . . . . 12
7.1.1.1. Handling media stream updates . . . . . . . . . . 13 7.1.1.1. Handling media stream updates . . . . . . . . . . 13
7.1.2. Recording indication in CS . . . . . . . . . . . . . 13 7.1.2. Recording indication in CS . . . . . . . . . . . . . 13
7.1.3. Recording preference in CS . . . . . . . . . . . . . 14 7.1.3. Recording preference in CS . . . . . . . . . . . . . 14
7.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 14 7.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 14
7.3. Procedures for Recording-aware User Agents . . . . . . . 16 7.3. Procedures for Recording-aware User Agents . . . . . . . 16
7.3.1. Recording indication . . . . . . . . . . . . . . . . 16 7.3.1. Recording indication . . . . . . . . . . . . . . . . 17
7.3.2. Recording preference . . . . . . . . . . . . . . . . 17 7.3.2. Recording preference . . . . . . . . . . . . . . . . 17
8. RTP Handling . . . . . . . . . . . . . . . . . . . . . . . . 18 8. RTP Handling . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1. RTP Mechanisms . . . . . . . . . . . . . . . . . . . . . 18 8.1. RTP Mechanisms . . . . . . . . . . . . . . . . . . . . . 18
8.1.1. RTCP . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1.1. RTCP . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1.2. RTP Profile . . . . . . . . . . . . . . . . . . . . . 19 8.1.2. RTP Profile . . . . . . . . . . . . . . . . . . . . . 19
8.1.3. SSRC . . . . . . . . . . . . . . . . . . . . . . . . 19 8.1.3. SSRC . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1.4. CSRC . . . . . . . . . . . . . . . . . . . . . . . . 20 8.1.4. CSRC . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1.5. SDES . . . . . . . . . . . . . . . . . . . . . . . . 20 8.1.5. SDES . . . . . . . . . . . . . . . . . . . . . . . . 20
8.1.5.1. CNAME . . . . . . . . . . . . . . . . . . . . . . 20 8.1.5.1. CNAME . . . . . . . . . . . . . . . . . . . . . . 20
8.1.6. Keepalive . . . . . . . . . . . . . . . . . . . . . . 20 8.1.6. Keepalive . . . . . . . . . . . . . . . . . . . . . . 20
8.1.7. RTCP Feedback Messages . . . . . . . . . . . . . . . 20 8.1.7. RTCP Feedback Messages . . . . . . . . . . . . . . . 21
8.1.7.1. Full Intra Request . . . . . . . . . . . . . . . 21 8.1.7.1. Full Intra Request . . . . . . . . . . . . . . . 21
8.1.7.2. Picture Loss Indicator . . . . . . . . . . . . . 21 8.1.7.2. Picture Loss Indicator . . . . . . . . . . . . . 21
8.1.7.3. Temporary Maximum Media Stream Bit Rate Request . 22 8.1.7.3. Temporary Maximum Media Stream Bit Rate Request . 22
8.1.8. Symmetric RTP/RTCP for Sending and Receiving . . . . 22 8.1.8. Symmetric RTP/RTCP for Sending and Receiving . . . . 22
8.2. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 22 8.2. Roles . . . . . . . . . . . . . . . . . . . . . . . . . . 23
8.2.1. SRC acting as an RTP Translator . . . . . . . . . . . 23 8.2.1. SRC acting as an RTP Translator . . . . . . . . . . . 24
8.2.1.1. Forwarding Translator . . . . . . . . . . . . . . 23 8.2.1.1. Forwarding Translator . . . . . . . . . . . . . . 24
8.2.1.2. Transcoding Translator . . . . . . . . . . . . . 24 8.2.1.2. Transcoding Translator . . . . . . . . . . . . . 24
8.2.2. SRC acting as an RTP Mixer . . . . . . . . . . . . . 25 8.2.2. SRC acting as an RTP Mixer . . . . . . . . . . . . . 25
8.2.3. SRC acting as an RTP Endpoint . . . . . . . . . . . . 25 8.2.3. SRC acting as an RTP Endpoint . . . . . . . . . . . . 26
8.3. RTP Session Usage by SRC . . . . . . . . . . . . . . . . 26 8.3. RTP Session Usage by SRC . . . . . . . . . . . . . . . . 26
8.3.1. SRC Using Multiple m-lines . . . . . . . . . . . . . 26 8.3.1. SRC Using Multiple m-lines . . . . . . . . . . . . . 26
8.3.2. SRC Using Mixing . . . . . . . . . . . . . . . . . . 27 8.3.2. SRC Using Mixing . . . . . . . . . . . . . . . . . . 27
8.4. RTP Session Usage by SRS . . . . . . . . . . . . . . . . 28 8.4. RTP Session Usage by SRS . . . . . . . . . . . . . . . . 28
9. Metadata . . . . . . . . . . . . . . . . . . . . . . . . . . 29 9. Metadata . . . . . . . . . . . . . . . . . . . . . . . . . . 29
9.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 29 9.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 29
9.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 30 9.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 31
9.2.1. Formal Syntax . . . . . . . . . . . . . . . . . . . . 32 9.2.1. Formal Syntax . . . . . . . . . . . . . . . . . . . . 32
10. Persistent Recording . . . . . . . . . . . . . . . . . . . . 32 10. Persistent Recording . . . . . . . . . . . . . . . . . . . . 32
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33
11.1. Registration of Option Tags . . . . . . . . . . . . . . 32 11.1. Registration of Option Tags . . . . . . . . . . . . . . 33
11.1.1. siprec Option Tag . . . . . . . . . . . . . . . . . 32 11.1.1. siprec Option Tag . . . . . . . . . . . . . . . . . 33
11.1.2. record-aware Option Tag . . . . . . . . . . . . . . 33 11.1.2. record-aware Option Tag . . . . . . . . . . . . . . 33
11.2. Registration of media feature tags . . . . . . . . . . . 33 11.2. Registration of media feature tags . . . . . . . . . . . 34
11.2.1. src feature tag . . . . . . . . . . . . . . . . . . 33 11.2.1. src feature tag . . . . . . . . . . . . . . . . . . 34
11.2.2. srs feature tag . . . . . . . . . . . . . . . . . . 33 11.2.2. srs feature tag . . . . . . . . . . . . . . . . . . 34
11.3. New Content-Disposition Parameter Registrations . . . . 34 11.3. New Content-Disposition Parameter Registrations . . . . 35
11.4. Media Type Registration . . . . . . . . . . . . . . . . 34 11.4. Media Type Registration . . . . . . . . . . . . . . . . 35
11.4.1. Registration of MIME Type application/rs-metadata . 34 11.4.1. Registration of MIME Type application/rs-metadata . 35
11.4.2. Registration of MIME Type application/rs-metadata- 11.4.2. Registration of MIME Type application/rs-metadata-
request . . . . . . . . . . . . . . . . . . . . . . 34 request . . . . . . . . . . . . . . . . . . . . . . 35
11.5. SDP Attributes . . . . . . . . . . . . . . . . . . . . . 35 11.5. SDP Attributes . . . . . . . . . . . . . . . . . . . . . 35
11.5.1. 'record' SDP Attribute . . . . . . . . . . . . . . . 35 11.5.1. 'record' SDP Attribute . . . . . . . . . . . . . . . 35
11.5.2. 'recordpref' SDP Attribute . . . . . . . . . . . . . 35 11.5.2. 'recordpref' SDP Attribute . . . . . . . . . . . . . 36
12. Security Considerations . . . . . . . . . . . . . . . . . . . 36 12. Security Considerations . . . . . . . . . . . . . . . . . . . 36
12.1. Authentication and Authorization . . . . . . . . . . . . 36 12.1. Authentication and Authorization . . . . . . . . . . . . 37
12.2. RTP handling . . . . . . . . . . . . . . . . . . . . . . 37 12.2. RTP handling . . . . . . . . . . . . . . . . . . . . . . 37
12.3. Metadata . . . . . . . . . . . . . . . . . . . . . . . . 37 12.3. Metadata . . . . . . . . . . . . . . . . . . . . . . . . 38
12.4. Storage and playback . . . . . . . . . . . . . . . . . . 38 12.4. Storage and playback . . . . . . . . . . . . . . . . . . 38
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 38 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 38
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 38 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 39
14.1. Normative References . . . . . . . . . . . . . . . . . . 38 14.1. Normative References . . . . . . . . . . . . . . . . . . 39
14.2. Informative References . . . . . . . . . . . . . . . . . 39 14.2. Informative References . . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 41
1. Introduction 1. Introduction
This document specifies the mechanism to record a Communication This document specifies the mechanism to record a Communication
Session (CS) by delivering real-time media and metadata from the CS Session (CS) by delivering real-time media and metadata from the CS
to a recording device. In accordance to the architecture to a recording device. In accordance to the architecture
[I-D.ietf-siprec-architecture], the Session Recording Protocol [I-D.ietf-siprec-architecture], the Session Recording Protocol
specifies the use of SIP, SDP, and RTP to establish a Recording specifies the use of SIP, SDP, and RTP to establish a Recording
Session (RS) between the Session Recording Client (SRC), which is on Session (RS) between the Session Recording Client (SRC), which is on
the path of the CS, and a Session Recording Server (SRS) at the the path of the CS, and a Session Recording Server (SRS) at the
recording device. recording device.
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o Policies governing how CS users are made aware of recording o Policies governing how CS users are made aware of recording
o Delivering additional recording session metadata through non-SIP o Delivering additional recording session metadata through non-SIP
mechanism mechanism
5. Overview of operations 5. Overview of operations
This section is informative and provides a description of recording This section is informative and provides a description of recording
operations. operations.
Section 6 describes SIP the handling in a recording session between a Section 6 describes the SIP communication in a recording session
SRC and a SRS, and the procedures for recording-aware user agents between a SRC and a SRS, and the procedures for recording-aware user
participating in a CS. Section 7 describes the SDP in a recording agents participating in a CS. Section 7 describes the SDP in a
session, and the procedures for recording indications and recording recording session, and the procedures for recording indications and
preferences. Section 8 describes the RTP handling in a recording recording preferences. Section 8 describes the RTP handling in a
session. Section 9 describes the mechanism to deliver recording recording session. Section 9 describes the mechanism to deliver
metadata from the SRC to the SRS. recording metadata from the SRC to the SRS.
As mentioned in the architecture document As mentioned in the architecture document
[I-D.ietf-siprec-architecture], there are a number of types of call [I-D.ietf-siprec-architecture], there are a number of types of call
flows based on the location of the Session Recording Client. The flows based on the location of the Session Recording Client. The
following sample call flows provide a quick overview of the following sample call flows provide a quick overview of the
operations between the SRC and the SRS. operations between the SRC and the SRS.
5.1. Delivering recorded media 5.1. Delivering recorded media
When a SIP Back-to-back User Agent (B2BUA) with SRC functionality When a SIP Back-to-back User Agent (B2BUA) with SRC functionality
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The SRC can initiate a recording session by sending a SIP INVITE The SRC can initiate a recording session by sending a SIP INVITE
request to the SRS. The SRC and the SRS are identified in the From request to the SRS. The SRC and the SRS are identified in the From
and To headers, respectively. and To headers, respectively.
The SRC MUST include the '+sip.src' feature tag in the Contact URI, The SRC MUST include the '+sip.src' feature tag in the Contact URI,
defined in this specification as an extension to [RFC3840], for all defined in this specification as an extension to [RFC3840], for all
recording sessions. An SRS uses the presence of the '+sip.src' recording sessions. An SRS uses the presence of the '+sip.src'
feature tag in dialog creating and modifying requests and responses feature tag in dialog creating and modifying requests and responses
to confirm that the dialog being created is for the purpose of a to confirm that the dialog being created is for the purpose of a
Recording Session. In addition, when an SRC sends a REGISTER request Recording Session. In addition, when an SRC sends a REGISTER request
to a registrar, the SRC MUST include the '+sip.src' feature tag to to a registrar, the SRC MAY include the '+sip.src' feature tag to
indicate the that it is a SRC. indicate the that it is a SRC.
Since SIP Caller Preferences extensions are optional to implement for Since SIP Caller Preferences extensions are optional to implement for
routing proxies, there is no guarantee that a recording session will routing proxies, there is no guarantee that a recording session will
be routed to an SRC or SRS. A new options tag is introduced: be routed to an SRC or SRS. A new options tag is introduced:
"siprec". As per [RFC3261], only an SRC or an SRS can accept this "siprec". As per [RFC3261], only an SRC or an SRS can accept this
option tag in a recording session. An SRC MUST include the "siprec" option tag in a recording session. An SRC MUST include the "siprec"
option tag in the Require header when initiating a Recording Session option tag in the Require header when initiating a Recording Session
so that UA's which do not support the session recording protocol so that UA's which do not support the session recording protocol
extensions will simply reject the INVITE request with a 420 Bad extensions will simply reject the INVITE request with a 420 Bad
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6.1.2. SIP extensions for recording indication and preference 6.1.2. SIP extensions for recording indication and preference
For the communication session, the SRC MUST provide recording For the communication session, the SRC MUST provide recording
indication to all participants in the CS. A participant UA in a CS indication to all participants in the CS. A participant UA in a CS
can indicate that it is recording-aware by providing the "record- can indicate that it is recording-aware by providing the "record-
aware" option tag, and the SRC MUST provide recording indications in aware" option tag, and the SRC MUST provide recording indications in
the new SDP a=record attribute described in the SDP Handling section. the new SDP a=record attribute described in the SDP Handling section.
In the absence of the "record-aware" option tag, meaning that the In the absence of the "record-aware" option tag, meaning that the
participant UA is not recording-aware, an SRC MUST provide recording participant UA is not recording-aware, an SRC MUST provide recording
indications through other means such as playing a tone inband, if the indications through other means such as playing a tone inband, if the
SRC is required to do so (e.g. based on policies). SRC is required to do so (e.g. based on policies).
An SRC in the CS may also indicate itself as a session recording An SRC in the CS may also indicate itself as a session recording
client by including the '+sip.src' feature tag. A recording-aware client by including the '+sip.src' feature tag. A recording-aware
participant can learn that a SRC is in the CS, and can set the participant can learn that a SRC is in the CS, and can set the
recording preference for the CS with the new SDP a=recordpref recording preference for the CS with the new SDP a=recordpref
attribute described in the SDP Handling section below. attribute described in the SDP Handling section below.
6.2. Procedures at the SRS 6.2. Procedures at the SRS
When an SRS receives a new INVITE, the SRS MUST only consider the SIP When an SRS receives a new INVITE, the SRS MUST only consider the SIP
session as a recording session when both the '+sip.src' feature tag session as a recording session when both the '+sip.src' feature tag
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The SRS can initiate a recording session by sending a SIP INVITE The SRS can initiate a recording session by sending a SIP INVITE
request to the SRC. The SRS and the SRC are identified in the From request to the SRC. The SRS and the SRC are identified in the From
and To headers, respectively. and To headers, respectively.
The SRS MUST include the '+sip.srs' feature tag in the Contact URI, The SRS MUST include the '+sip.srs' feature tag in the Contact URI,
as per [RFC3840], for all recording sessions. An SRC uses the as per [RFC3840], for all recording sessions. An SRC uses the
presence of this feature tag in dialog creating and modifying presence of this feature tag in dialog creating and modifying
requests and responses to confirm that the dialog being created is requests and responses to confirm that the dialog being created is
for the purpose of a Recording Session (REQ-30). In addition, when for the purpose of a Recording Session (REQ-30). In addition, when
an SRS sends a REGISTER request to a registrar, the SRS MUST include an SRS sends a REGISTER request to a registrar, the SRS SHOULD
the '+sip.srs' feature tag to indicate that it is a SRS. include the '+sip.srs' feature tag to indicate that it is a SRS.
An SRS MUST include the "siprec" option tag in the Require header as An SRS MUST include the "siprec" option tag in the Require header as
per [RFC3261] when initiating a Recording Session so that UA's which per [RFC3261] when initiating a Recording Session so that UA's which
do not support the session recording protocol extensions will simply do not support the session recording protocol extensions will simply
reject the INVITE request with a 420 Bad Extension. reject the INVITE request with a 420 Bad Extension.
6.3. Procedures for Recording-aware User Agents 6.3. Procedures for Recording-aware User Agents
A recording-aware user agent is a participant in the CS that supports A recording-aware user agent is a participant in the CS that supports
the SIP and SDP extensions for receiving recording indication and for the SIP and SDP extensions for receiving recording indication and for
requesting recording preferences for the call. A recording-aware UA requesting recording preferences for the call. A recording-aware UA
MUST indicate that it can accept reporting of recording indication MUST indicate that it can accept reporting of recording indication
provided by the SRC with a new option tag "record-aware" when provided by the SRC with a new option tag "record-aware" when
initiating or establishing a CS, meaning including the "record-aware" initiating or establishing a CS, meaning including the "record-aware"
tag in the Supported header in the initial INVITE request or tag in the Supported header in the initial INVITE request or
response. response.
A recording-aware UA MUST be prepared to provide recording indication A recording-aware UA MUST be prepared to provide a recording
to the end user through an appropriate user interface an indication indication to the end user through an appropriate user interface,
whether recording is on, off, or paused for each medium. Some user indicating whether recording is on, off, or paused for each medium.
agents that are automatons (e.g. IVR, media server, PSTN gateway) Some user agents that are automatons (e.g. IVR, media server, PSTN
may not have a user interface to render recording indication. When gateway) may not have a user interface to render recording
such user agent indicates recording awareness, the UA SHOULD render indication. When such user agent indicates recording awareness, the
recording indication through other means, such as passing an inband UA SHOULD render recording indication through other means, such as
tone on the PSTN gateway, putting the recording indication in a log passing an inband tone on the PSTN gateway, putting the recording
file, or raising an application event in a VoiceXML dialog. These indication in a log file, or raising an application event in a
user agents MAY also choose not to indicate recording awareness, VoiceXML dialog. These user agents MAY also choose not to indicate
thereby relying on whatever mechanism an SRC chooses to indicate recording awareness, thereby relying on whatever mechanism an SRC
recording, such as playing a tone inband. chooses to indicate recording, such as playing a tone inband.
7. SDP Handling 7. SDP Handling
7.1. Procedures at the SRC 7.1. Procedures at the SRC
The SRC and SRS follows the SDP offer/answer model in [RFC3264]. The The SRC and SRS follows the SDP offer/answer model in [RFC3264]. The
procedures for SRC and SRS describe the conventions used in a procedures for SRC and SRS describe the conventions used in a
recording session. recording session.
7.1.1. SDP handling in RS 7.1.1. SDP handling in RS
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The SRC can temporarily discontinue streaming and collection of The SRC can temporarily discontinue streaming and collection of
recorded media from the SRC to the SRS for reasons such as masking recorded media from the SRC to the SRS for reasons such as masking
the recording. In this case, the SRC sends a new SDP offer and sets the recording. In this case, the SRC sends a new SDP offer and sets
the media stream to inactive (a=inactive) for each recorded stream to the media stream to inactive (a=inactive) for each recorded stream to
be paused, as per the procedures in [RFC3264]. To resume streaming be paused, as per the procedures in [RFC3264]. To resume streaming
and collection of recorded media, the SRC sends a new SDP offer and and collection of recorded media, the SRC sends a new SDP offer and
sets the media stream to sendonly (a=sendonly). Note that a CS sets the media stream to sendonly (a=sendonly). Note that a CS
itself may change the media stream direction by updating the SDP, for itself may change the media stream direction by updating the SDP, for
example, by setting a=inactive for SDP hold. Media stream direction example, by setting a=inactive for SDP hold. Media stream direction
changes in CS are conveyed in the metadata by the SRC. The SRC MUST changes in CS are conveyed in the metadata by the SRC. The SRC MUST
NOT modify the media stream with a=inactive for SDP hold on the CS NOT modify the RS media stream with a=inactive for SDP hold on the CS
since this operation is reserved for pausing the RS media, however, since this operation is reserved for pausing the RS media, however,
an SRC can have a local policy to pause the RS media when the CS is an SRC can have a local policy to pause the RS media when the CS is
placed on hold. placed on hold.
7.1.2. Recording indication in CS 7.1.2. Recording indication in CS
While there are existing mechanisms for providing an indication that While there are existing mechanisms for providing an indication that
a CS is being recorded, these mechanisms are usually delivered on the a CS is being recorded, these mechanisms are usually delivered on the
CS media streams such as playing an in-band tone or an announcement CS media streams such as playing an in-band tone or an announcement
to the participants. A new 'record' SDP attribute is introduced to to the participants. A new 'record' SDP attribute is introduced to
skipping to change at page 14, line 21 skipping to change at page 14, line 21
at the session level, the indication applies to all media streams in at the session level, the indication applies to all media streams in
the SDP. When the attribute is applied at the media level, the the SDP. When the attribute is applied at the media level, the
indication applies to the media stream only, and that overrides the indication applies to the media stream only, and that overrides the
indication if also set at the session level. Whenever the recording indication if also set at the session level. Whenever the recording
indication needs to change, such as termination of recording, then indication needs to change, such as termination of recording, then
the SRC MUST initiate a reINVITE or UPDATE to update the SDP a=record the SRC MUST initiate a reINVITE or UPDATE to update the SDP a=record
attribute. attribute.
The following is the ABNF of the 'record' attribute: The following is the ABNF of the 'record' attribute:
attribute /= record-attr attribute /= record-attr
; attribute defined in RFC 4566
; attribute defined in RFC 4566
record-attr = "record:" indication
indication = "on" / "off" / "paused" record-attr = "record:" indication
indication = "on" / "off" / "paused"
on Recording is in progress. on Recording is in progress.
off No recording is in progress. off No recording is in progress.
paused Recording is in progress but media is paused. paused Recording is in progress but media is paused.
7.1.3. Recording preference in CS 7.1.3. Recording preference in CS
When the SRC receives the a=recordpref SDP in an SDP offer or answer, When the SRC receives the a=recordpref SDP in an SDP offer or answer,
the SRC chooses to honor the preference to record based on local the SRC chooses to honor the preference to record based on local
policy at the SRC. Whether or not the SRC honors the recording policy at the SRC. If the SRC makes a change in recording state,
preference, the SRC MUST update the a=record attribute to indicate then the SRC reports the recording state in the a=record attribute in
the current state of the recording (on/off/paused). the SDP answer or in a subsequent SDP offer/answer.
7.2. Procedures at the SRS 7.2. Procedures at the SRS
Typically the SRS only receives RTP streams from the SRC; therefore, Typically the SRS only receives RTP streams from the SRC; therefore,
the SDP offer/answer from the SRS normally sets each media stream to the SDP offer/answer from the SRS normally sets each media stream to
receive media, by setting them with the a=recvonly attribute, receive media, by setting them with the a=recvonly attribute,
according to the procedures of [RFC3264]. When the SRS is not ready according to the procedures of [RFC3264]. When the SRS is not ready
to receive a recorded stream, the SRS sets the media stream as to receive a recorded stream, the SRS sets the media stream as
inactive in the SDP offer or answer by setting it with a=inactive inactive in the SDP offer or answer by setting it with a=inactive
attribute, according to the procedures of [RFC3264]. When the SRS is attribute, according to the procedures of [RFC3264]. When the SRS is
ready to receive recorded streams, the SRS sends a new SDP offer and ready to receive recorded streams, the SRS sends a new SDP offer and
sets the media streams with a=recvonly attribute. sets the media streams with a=recvonly attribute.
skipping to change at page 16, line 42 skipping to change at page 17, line 4
|====================================================>| |====================================================>|
| ... | | ... |
|(8) BYE | |(8) BYE |
|---------------------------------------------------->| |---------------------------------------------------->|
| (9) OK | | (9) OK |
|<----------------------------------------------------| |<----------------------------------------------------|
Figure 6: SRS responding to offer with a=inactive Figure 6: SRS responding to offer with a=inactive
7.3. Procedures for Recording-aware User Agents 7.3. Procedures for Recording-aware User Agents
7.3.1. Recording indication 7.3.1. Recording indication
When a recording-aware UA receives an SDP offer or answer that When a recording-aware UA receives an SDP offer or answer that
includes the a=record attribute, the UA MUST provide the recording includes the a=record attribute, the UA MUST provide the recording
indication to the end user whether the recording is on, off, or indication to the end user whether the recording is on, off, or
paused for each medium based on the most recently received a=record paused for each medium based on the most recently received a=record
SDP attribute for that medium. SDP attribute for that medium.
If a call is traversed through one or more SIP B2BUA, and it happens When a CS is traversed through multiple UAs such as a B2BUA or a
that there are more than one SRC in the call path, the recording conference focus, each UA involved in the CS that is aware that the
indication attribute does not provide any hint as to which SRC is CS is being recorded MUST provide the recording indication through
performing the recording, meaning the endpoint only knows that the the a=record attribute to all other parties in the CS.
call is being recorded. This attribute is also not used as an
indication to negotiate which SRC in the call path will perform It is possible that more than one SRC can be in the call path
recording and is not used as a request to start/stop recording if recording the same CS, but the recording indication attribute does
there are multiple SRCs in the call path. not provide any hint as to which SRC is actually performing the
recording. This means that an endpoint only knows that the call is
being recorded through the recording indicator. This attribute is
also not used as an indication to negotiate which SRC in the call
path will perform recording and is not used as a request to start/
stop recording if there are multiple SRCs in the call path.
7.3.2. Recording preference 7.3.2. Recording preference
A participant in a CS MAY set the recording preference in the CS to A participant in a CS MAY set the recording preference in the CS to
be recorded or not recorded at session establishment or during the be recorded or not recorded at session establishment or during the
session. A new 'recordpref' SDP attribute is introduced, and the session. A new 'recordpref' SDP attribute is introduced, and the
participant in CS may set this recording preference attribute in any participant in CS may set this recording preference attribute in any
SDP offer/answer at session establishment time or during the session. SDP offer/answer at session establishment time or during the session.
The SRC is not required to honor the recording preference from a The SRC is not required to honor the recording preference from a
participant based on local policies at the SRC, and the participant participant based on local policies at the SRC, and the participant
skipping to change at page 17, line 40 skipping to change at page 18, line 5
applied at the media level, the recording preference applies to the applied at the media level, the recording preference applies to the
media stream only, and that overrides the recording preference if media stream only, and that overrides the recording preference if
also set at the session level. The user agent can change the also set at the session level. The user agent can change the
recording preference by changing the a=recordpref attribute in recording preference by changing the a=recordpref attribute in
subsequent SDP offer or answer. The absence of the a=recordpref subsequent SDP offer or answer. The absence of the a=recordpref
attribute in the SDP indicates that the UA has no recording attribute in the SDP indicates that the UA has no recording
preference. preference.
The following is the ABNF of the recordpref attribute: The following is the ABNF of the recordpref attribute:
attribute /= recordpref-attr attribute /= recordpref-attr
; attribute defined in RFC 4566
; attribute defined in RFC 4566
recordpref-attr = "a=recordpref:" pref
pref = "on" / "off" / "pause" / "nopreference" recordpref-attr = "a=recordpref:" pref
pref = "on" / "off" / "pause" / "nopreference"
on Sets the preference to record if it has not already been started. on Sets the preference to record if it has not already been started.
If the recording is currently paused, the preference is to resume If the recording is currently paused, the preference is to resume
recording. recording.
off Sets the preference for no recording. If recording has already off Sets the preference for no recording. If recording has already
been started, then the preference is to stop the recording. been started, then the preference is to stop the recording.
pause If the recording is currently in progress, sets the preference pause If the recording is currently in progress, sets the preference
to pause the recording. to pause the recording.
skipping to change at page 20, line 37 skipping to change at page 20, line 48
8.1.5.1. CNAME 8.1.5.1. CNAME
The Canonical End-Point Identifier (CNAME), as defined in [RFC3550], The Canonical End-Point Identifier (CNAME), as defined in [RFC3550],
provides the binding from the SSRC identifier to an identifier for provides the binding from the SSRC identifier to an identifier for
the source (sender or receiver) that remains constant. It is the source (sender or receiver) that remains constant. It is
important the SRC and Recording aware UAs generate CNAMEs important the SRC and Recording aware UAs generate CNAMEs
appropriately and that the SRC and SRS interpret and use them for appropriately and that the SRC and SRS interpret and use them for
this purpose. Guidelines for generating CNAME values are provided in this purpose. Guidelines for generating CNAME values are provided in
"Guidelines for Choosing RTP Control Protocol (RTCP) Canonical Names "Guidelines for Choosing RTP Control Protocol (RTCP) Canonical Names
(CNAMEs)" [RFC6222]. (CNAMEs)" [RFC7022].
8.1.6. Keepalive 8.1.6. Keepalive
It is anticipated that media streams in SIPREC may exist in an It is anticipated that media streams in SIPREC may exist in an
inactive state for extended periods of times for any of a number of inactive state for extended periods of times for any of a number of
valid reasons. In order for the bindings and any pinholes in NATs/ valid reasons. In order for the bindings and any pinholes in NATs/
firewalls to remain active during such intervals, it is RECOMMENDED firewalls to remain active during such intervals, it is RECOMMENDED
that the SRC, SRS, and Recording aware UAs follow the keep-alive that the SRC, SRS, and Recording aware UAs follow the keep-alive
procedure recommended in "Application Mechanism for Keeping Alive the procedure recommended in "Application Mechanism for Keeping Alive the
NAT Mappings Associated to RTP/RTP Control Protocol (RTCP) Flows" NAT Mappings Associated to RTP/RTP Control Protocol (RTCP) Flows"
[RFC6263] for all RTP media streams. [RFC6263] for all RTP media streams.
8.1.7. RTCP Feedback Messages 8.1.7. RTCP Feedback Messages
skipping to change at page 22, line 47 skipping to change at page 23, line 10
it will receive RTCP as well as send RTP and RTCP. it will receive RTCP as well as send RTP and RTCP.
Note: Symmetric RTP and symmetric RTCP are different from RTP/RTCP Note: Symmetric RTP and symmetric RTCP are different from RTP/RTCP
multiplexing [RFC5761]. multiplexing [RFC5761].
8.2. Roles 8.2. Roles
An SRC has the task of gathering media from the various UAs in one or An SRC has the task of gathering media from the various UAs in one or
more Communication Sessions (CSs) and forwarding the information to more Communication Sessions (CSs) and forwarding the information to
the SRS within the context of a corresponding Recording Session (RS). the SRS within the context of a corresponding Recording Session (RS).
There are numerous ways in which an SRC may do this is, including but There are numerous ways in which an SRC may do this, including but
not limited to, appearing as a UA within a CS, or as a B2BUA between not limited to, appearing as a UA within a CS, or as a B2BUA between
UAs within a CS. UAs within a CS.
(Recording Session) +---------+ (Recording Session) +---------+
+------------SIP------->| | +------------SIP------->| |
| +------RTP/RTCP----->| SRS | | +------RTP/RTCP----->| SRS |
| | +-- Metadata -->| | | | +-- Metadata -->| |
| | | +---------+ | | | +---------+
v v | v v |
+---------+ +---------+
skipping to change at page 26, line 47 skipping to change at page 27, line 17
which an alternative RTP session usage is negotiated. which an alternative RTP session usage is negotiated.
In order to preserve the mapping of media to participant within the In order to preserve the mapping of media to participant within the
CSs in the RS, the SRC SHOULD map each unique CNAME within the CSs to CSs in the RS, the SRC SHOULD map each unique CNAME within the CSs to
a unique CNAME within the RS. Additionally, the SRC SHOULD map each a unique CNAME within the RS. Additionally, the SRC SHOULD map each
unique combination of CNAME/SSRC within the CSs to a unique CNAME/ unique combination of CNAME/SSRC within the CSs to a unique CNAME/
SSRC within the RS. In doing to, the SRC may act as an RTP SSRC within the RS. In doing to, the SRC may act as an RTP
translator or as an RTP endpoint. translator or as an RTP endpoint.
The following figure illustrates a case in which each UA represents a The following figure illustrates a case in which each UA represents a
participant contributing two RTP sessions (e.g. one for audio and participant contributing two RTP sessions (e.g. one for audio and one
one for video), each with a single SSRC. The SRC acts as an RTP for video), each with a single SSRC. The SRC acts as an RTP
translator and delivers the media to the SRS using four RTP sessions, translator and delivers the media to the SRS using four RTP sessions,
each with a single SSRC. The CNAME and SSRC values used by the UAs each with a single SSRC. The CNAME and SSRC values used by the UAs
within their media streams are preserved in the media streams from within their media streams are preserved in the media streams from
the SRC to the SRS. the SRC to the SRS.
+---------+ +---------+
+------------SSRC Aa--->| | +------------SSRC Aa--->| |
| + --------SSRC Av--->| | | + --------SSRC Av--->| |
| | +------SSRC Ba--->| SRS | | | +------SSRC Ba--->| SRS |
| | | +---SSRC Bv--->| | | | | +---SSRC Bv--->| |
skipping to change at page 27, line 45 skipping to change at page 28, line 18
unique combination of CNAME/SSRC within the CSs to a unique CNAME/ unique combination of CNAME/SSRC within the CSs to a unique CNAME/
SSRC within the RS. The SRC MUST avoid SSRC collisions, rewriting SSRC within the RS. The SRC MUST avoid SSRC collisions, rewriting
SSRCs if necessary when used as CSRCs in the RS. In doing to, the SSRCs if necessary when used as CSRCs in the RS. In doing to, the
SRC acts as an RTP mixer. SRC acts as an RTP mixer.
In the event the SRS does not support this usage of CSRC values, it In the event the SRS does not support this usage of CSRC values, it
relies entirely on the SIPREC metadata to determine the participants relies entirely on the SIPREC metadata to determine the participants
included within each mixed stream. included within each mixed stream.
The following figure illustrates a case in which each UA represents a The following figure illustrates a case in which each UA represents a
participant contributing two RTP sessions (e.g. one for audio and participant contributing two RTP sessions (e.g. one for audio and one
one for video), each with a single SSRC. The SRC acts as an RTP for video), each with a single SSRC. The SRC acts as an RTP mixer
mixer and delivers the media to the SRS using two RTP sessions, and delivers the media to the SRS using two RTP sessions, mixing
mixing media from each participant into a single RTP session media from each participant into a single RTP session containing a
containing a single SSRC and two CSRCs. single SSRC and two CSRCs.
SSRC Sa +---------+ SSRC Sa +---------+
+-------CSRC Aa,Ba--->| | +-------CSRC Aa,Ba--->| |
| | | | | |
| SSRC Sa | SRS | | SSRC Sa | SRS |
| +---CSRC Av,Bv--->| | | +---CSRC Av,Bv--->| |
| | +---------+ | | +---------+
| | | |
+----------+ +----------+
+---------+ | SRC | +---------+ +---------+ | SRC | +---------+
skipping to change at page 28, line 30 skipping to change at page 29, line 5
An SRS that supports recording an audio CS MUST support SRC usage of An SRS that supports recording an audio CS MUST support SRC usage of
separate audio m-lines in SDP, one per CS media direction. An SRS separate audio m-lines in SDP, one per CS media direction. An SRS
that supports recording an video CS MUST support SRC usage of that supports recording an video CS MUST support SRC usage of
separate video m-lines in SDP, one per CS media direction. separate video m-lines in SDP, one per CS media direction.
Therefore, for an SRS supporting a typical audio call, the SRS has to Therefore, for an SRS supporting a typical audio call, the SRS has to
support receiving at least two audio m-lines. For an SRS supporting support receiving at least two audio m-lines. For an SRS supporting
a typical audio and video call, the SRS has to support receiving at a typical audio and video call, the SRS has to support receiving at
least four total m-lines in the SDP, two audio m-lines and two video least four total m-lines in the SDP, two audio m-lines and two video
m-lines. m-lines.
Note that these requirements allow an SRS to be implemented that These requirements allow an SRS to be implemented that supports video
supports video only, without requiring support for audio recording. only, without requiring support for audio recording. They also allow
They also allow an SRS to be implemented that supports recording only an SRS to be implemented that supports recording only one direction
one direction of one stream in a CS; for example, an SRS designed to of one stream in a CS; for example, an SRS designed to record
record security monitoring cameras that only send (not receive) video security monitoring cameras that only send (not receive) video
without any audio. These requirements were not written to prevent without any audio. These requirements were not written to prevent
other modes being implemented and used, such as using a single m-line other modes being implemented and used, such as using a single m-line
and mixing the separate audio streams together. Rather, the and mixing the separate audio streams together. Rather, the
requirements were written to provide a common base mode to implement requirements were written to provide a common base mode to implement
for the sake of interoperability. It is important to note that an for the sake of interoperability. It is important to note that an
SRS implementation supporting the common base may not record all SRS implementation supporting the common base may not record all
media streams in a CS if a participant supports more than one m-line media streams in a CS if a participant supports more than one m-line
in a video call, such as one for camera and one for presentation. in a video call, such as one for camera and one for presentation.
SRS implementations may support other modes as well, but have to at SRS implementations may support other modes as well, but have to at
least support the ones above such that they interoperate in the least support the ones above such that they interoperate in the
skipping to change at page 29, line 34 skipping to change at page 29, line 51
[I-D.ietf-siprec-metadata]. A new "disposition-type" of Content- [I-D.ietf-siprec-metadata]. A new "disposition-type" of Content-
Disposition is defined for the purpose of carrying metadata and the Disposition is defined for the purpose of carrying metadata and the
value is "recording-session". The "recording-session" value value is "recording-session". The "recording-session" value
indicates that the "application/rs-metadata" content contains indicates that the "application/rs-metadata" content contains
metadata to be handled by the SRS, and the disposition can be carried metadata to be handled by the SRS, and the disposition can be carried
in either INVITE or UPDATE requests or responses sent by the SRC. in either INVITE or UPDATE requests or responses sent by the SRC.
Metadata sent by the SRC can be categorized as either a full metadata Metadata sent by the SRC can be categorized as either a full metadata
snapshot or partial update. A full metadata snapshot describes all snapshot or partial update. A full metadata snapshot describes all
the recorded streams and all metadata associated with the recording the recorded streams and all metadata associated with the recording
session. When the SRC sends a full metadata snapshot, the SRC MUST session. The SRC MAY send a full metadata snapshot at any time. The
send an INVITE or an UPDATE request ([RFC3311]) with an SDP offer and SRC MAY send a partial update if a full metadata snapshot has
the "recording-session" disposition. A partial update represents an previously been sent. If the SRC receives a snapshot request from
incremental update since the last metadata update sent by the SRC. A the SRS, then it MUST immediately send a full metadata snapshot.
partial update sent by the SRC can be an INVITE request or response
with an SDP offer, or an INVITE/UPDATE request or response containing The SRC MAY send metadata (either a full metadata shapshot or a
a "recording-session" disposition, or an INVITE request containing partial update) in either an INVITE request, an UPDATE request
both an SDP offer and the "recording-session" disposition. ([RFC3311]), or in the final (200) response to an offerless INVITE
from the SRS. If any of the metadata being sent contains a reference
to any SDP labels, then the request containing the metadata MUST also
contain an SDP offer that defines those labels.
When an INVITE or UPDATE request contains both an SDP offer and
metadata, then the request body has content type multipart/mixed,
with one subordinate body part containing the SDP offer and another
containing the metadata. When an INVITE contains only an SDP offer
or metadata, then the multipart/mixed container is optional.
The following is an example of a full metadata snapshot sent by the The following is an example of a full metadata snapshot sent by the
SRC in the initial INVITE request: SRC in the initial INVITE request:
INVITE sip:recorder@example.com SIP/2.0 INVITE sip:recorder@example.com SIP/2.0
Via: SIP/2.0/TCP src.example.com;branch=z9hG4bKdf6b622b648d9 Via: SIP/2.0/TCP src.example.com;branch=z9hG4bKdf6b622b648d9
From: <sip:2000@example.com>;tag=35e195d2-947d-4585-946f-09839247 From: <sip:2000@example.com>;tag=35e195d2-947d-4585-946f-09839247
To: <sip:recorder@example.com> To: <sip:recorder@example.com>
Call-ID: d253c800-b0d1ea39-4a7dd-3f0e20a Call-ID: d253c800-b0d1ea39-4a7dd-3f0e20a
CSeq: 101 INVITE CSeq: 101 INVITE
Max-Forwards: 70 Max-Forwards: 70
Require: siprec Require: siprec
Accept: application/sdp, application/rs-metadata, Accept: application/sdp, application/rs-metadata-request
application/rs-metadata-request
Contact: <sip:2000@src.example.com>;+sip.src Contact: <sip:2000@src.example.com>;+sip.src
Content-Type: multipart/mixed;boundary=foobar Content-Type: multipart/mixed;boundary=foobar
Content-Length: [length] Content-Length: [length]
--foobar --foobar
Content-Type: application/sdp Content-Type: application/sdp
v=0 v=0
o=SRS 2890844526 2890844526 IN IP4 198.51.100.1 o=SRS 2890844526 2890844526 IN IP4 198.51.100.1
s=- s=-
skipping to change at page 31, line 5 skipping to change at page 31, line 27
recognize a partial update from the SRC. The SRS may be able to recognize a partial update from the SRC. The SRS may be able to
recover from the internal failure by requesting for a full metadata recover from the internal failure by requesting for a full metadata
snapshot from the SRC. Certain errors, such as syntax errors or snapshot from the SRC. Certain errors, such as syntax errors or
semantic errors in the metadata information, are likely caused by an semantic errors in the metadata information, are likely caused by an
error on the SRC side, and it is likely the same error will occur error on the SRC side, and it is likely the same error will occur
again even when a full metadata snapshot is requested. In order to again even when a full metadata snapshot is requested. In order to
avoid repeating the same error, the SRS can simply terminate the avoid repeating the same error, the SRS can simply terminate the
recording session when a syntax error or semantic error is detected recording session when a syntax error or semantic error is detected
in the metadata. in the metadata.
When the SRS explicitly requests for a full metadata snapshot, the The SRS MAY explicitly request a full metadata snapshot by sending an
SRS MUST send an UPDATE request without an SDP offer. A metadata UPDATE request. This request MUST contain a body with a content
snapshot request contains a content with the content disposition type disposition type "recording-session", and MUST NOT contain an SDP
"recording-session". Note that the SRS MAY generate an INVITE body part. Note that the SRS MAY generate an INVITE request without
request without an SDP offer but this MUST NOT include a metadata an SDP offer but this MUST NOT include a metadata snapshot request.
snapshot request. The format of the content is "application/rs- The format of the content is "application/rs-metadata-request", and
metadata-request", and the body format is chosen to be a simple text- the body format is chosen to be a simple text-based format. The
based format. The following shows an example: following shows an example:
UPDATE sip:2000@src.exmaple.com SIP/2.0 UPDATE sip:2000@src.exmaple.com SIP/2.0
Via: SIP/2.0/UDP srs.example.com;branch=z9hG4bKdf6b622b648d9 Via: SIP/2.0/UDP srs.example.com;branch=z9hG4bKdf6b622b648d9
To: <sip:2000@exmaple.com>;tag=35e195d2-947d-4585-946f-098392474 To: <sip:2000@exmaple.com>;tag=35e195d2-947d-4585-946f-098392474
From: <sip:recorder@example.com>;tag=1234567890 From: <sip:recorder@example.com>;tag=1234567890
Call-ID: d253c800-b0d1ea39-4a7dd-3f0e20a Call-ID: d253c800-b0d1ea39-4a7dd-3f0e20a
CSeq: 1 UPDATE CSeq: 1 UPDATE
Max-Forwards: 70 Max-Forwards: 70
Require: siprec Require: siprec
Contact: <sip:recorder@srs.example.com>;+sip.srs Contact: <sip:recorder@srs.example.com>;+sip.srs
skipping to change at page 31, line 40 skipping to change at page 32, line 16
Figure 12: Metadata Request Figure 12: Metadata Request
The SRS MAY include the reason why a metadata snapshot request is The SRS MAY include the reason why a metadata snapshot request is
being made to the SRC in the reason line. This reason line is free being made to the SRC in the reason line. This reason line is free
form text, mainly designed for logging purposes on the SRC side. The form text, mainly designed for logging purposes on the SRC side. The
processing of the content by the SRC is entirely optional since the processing of the content by the SRC is entirely optional since the
content is for logging only, and the snapshot request itself is content is for logging only, and the snapshot request itself is
indicated by the use of the application/rs-metadata-request content indicated by the use of the application/rs-metadata-request content
type. type.
When the SRC receives the request for a metadata snapshot, the SRC When the SRC receives a request for a metadata snapshot, it MUST
MUST provide a full metadata snapshot in a separate INVITE or UPDATE immediately provide a full metadata snapshot in a separate INVITE or
transaction, along with an SDP offer. All subsequent metadata UPDATE transaction. Any subsequent partial updates will not be
updates sent by the SRC MUST be based on the new metadata snapshot. dependent on any metadata sent prior to this full metadata snapshot.
The metadata received by the SRS can contain ID elements used to The metadata received by the SRS can contain ID elements used to
cross reference one element to another. An element containing the cross reference one element to another. An element containing the
definition of an ID, and an element containing a reference to that ID definition of an ID, and an element containing a reference to that ID
will often be received from the same SRC. It is also valid for those will often be received from the same SRC. It is also valid for those
elements to be received from different SRCs, for example, when each elements to be received from different SRCs, for example, when each
endpoint in the same CS act as an SRC to record the call and a common endpoint in the same CS act as an SRC to record the call and a common
ID refers to the same CS. The SRS MUST NOT consider this an error. ID refers to the same CS. The SRS MUST NOT consider this an error.
9.2.1. Formal Syntax 9.2.1. Formal Syntax
The formal syntax for the application/rs-metadata-request MIME is The formal syntax for the application/rs-metadata-request MIME is
described below using the augmented Backus-Naur Form (BNF) as described below using the augmented Backus-Naur Form (BNF) as
described in [RFC5234]. described in [RFC5234].
snapshot-request = srs-reason-line CRLF snapshot-request = srs-reason-line CRLF
srs-reason-line = [TEXT-UTF8-TRIM]
srs-reason-line = [TEXT-UTF8-TRIM] ; TEXT-UTF8-TRIM defined in RFC3261
10. Persistent Recording 10. Persistent Recording
Persistent recording is a specific use case outlined in REQ-005 or Persistent recording is a specific use case outlined in REQ-005 or
Use Case 4 in [RFC6341], where a recording session can be established Use Case 4 in [RFC6341], where a recording session can be established
in the absence of a communication session. The SRC continuously in the absence of a communication session. The SRC continuously
records media in a recording session to the SRS even in the absence records media in a recording session to the SRS even in the absence
of a CS for all user agents that are part of persistent recording. of a CS for all user agents that are part of persistent recording.
By allocating recorded streams and continuously sending recorded By allocating recorded streams and continuously sending recorded
media to the SRS, the SRC does not have to prepare new recorded media to the SRS, the SRC does not have to prepare new recorded
skipping to change at page 37, line 6 skipping to change at page 37, line 33
a different administrative domain, it is important to perform mutual a different administrative domain, it is important to perform mutual
authentication to ensure the authenticity of both the SRC and the SRS authentication to ensure the authenticity of both the SRC and the SRS
before transmitting any recorded media. The risk of not before transmitting any recorded media. The risk of not
authenticating the SRS is that the recording may be sent to a authenticating the SRS is that the recording may be sent to a
compromised SRS and that a sensitive call recording will be obtained compromised SRS and that a sensitive call recording will be obtained
by an attacker. On the other hand, the risk of not authenticating by an attacker. On the other hand, the risk of not authenticating
the SRC is that an SRS will accept calls from an unknown SRC and the SRC is that an SRS will accept calls from an unknown SRC and
allow potential forgery of call recordings. allow potential forgery of call recordings.
There may be scenarios in which the signaling between the SRC and SRS There may be scenarios in which the signaling between the SRC and SRS
is not direct, e.g. a SIP proxy exists between the SRC and the SRS. is not direct, e.g. a SIP proxy exists between the SRC and the SRS.
In such scenarios, each hop is subject to the TLS mutual In such scenarios, each hop is subject to the TLS mutual
authentication constraint and transitive trust at each hop is authentication constraint and transitive trust at each hop is
utilized. Additionally, an SRC or SRS may use other existing SIP utilized. Additionally, an SRC or SRS may use other existing SIP
mechanisms available, including but not limited to, Digest mechanisms available, including but not limited to, Digest
Authentication [RFC3261], Asserted Identity [RFC3325], and Connected Authentication [RFC3261], Asserted Identity [RFC3325], and Connected
Identity [RFC4916]. Identity [RFC4916].
The SRS may have its own set of recording policies to authorize The SRS may have its own set of recording policies to authorize
recording requests from the SRC. The use of recording policies is recording requests from the SRC. The use of recording policies is
outside the scope of the Session Recording Protocol. outside the scope of the Session Recording Protocol.
skipping to change at page 38, line 35 skipping to change at page 39, line 14
Muthu Perumal, Dan Wing, and Magnus Westerlund for their valuable Muthu Perumal, Dan Wing, and Magnus Westerlund for their valuable
comments and inputs to this document. comments and inputs to this document.
14. References 14. References
14.1. Normative References 14.1. Normative References
[I-D.ietf-siprec-metadata] [I-D.ietf-siprec-metadata]
R, R., Ravindran, P., and P. Kyzivat, "Session Initiation R, R., Ravindran, P., and P. Kyzivat, "Session Initiation
Protocol (SIP) Recording Metadata", draft-ietf-siprec- Protocol (SIP) Recording Metadata", draft-ietf-siprec-
metadata-11 (work in progress), January 2013. metadata-12 (work in progress), May 2013.
[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.
[RFC2506] Holtman, K., Mutz, A., and T. Hardie, "Media Feature Tag [RFC2506] Holtman, K., Mutz, A., and T. Hardie, "Media Feature Tag
Registration Procedure", BCP 31, RFC 2506, March 1999. Registration Procedure", BCP 31, RFC 2506, March 1999.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
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14.2. Informative References 14.2. Informative References
[I-D.ietf-avt-srtp-ekt] [I-D.ietf-avt-srtp-ekt]
Wing, D., McGrew, D., and K. Fischer, "Encrypted Key Wing, D., McGrew, D., and K. Fischer, "Encrypted Key
Transport for Secure RTP", draft-ietf-avt-srtp-ekt-03 Transport for Secure RTP", draft-ietf-avt-srtp-ekt-03
(work in progress), October 2011. (work in progress), October 2011.
[I-D.ietf-siprec-architecture] [I-D.ietf-siprec-architecture]
Hutton, A., Portman, L., Jain, R., and K. Rehor, "An Hutton, A., Portman, L., Jain, R., and K. Rehor, "An
Architecture for Media Recording using the Session Architecture for Media Recording using the Session
Initiation Protocol", draft-ietf-siprec-architecture-07 Initiation Protocol", draft-ietf-siprec-architecture-08
(work in progress), November 2012. (work in progress), May 2013.
[RFC3311] Rosenberg, J., "The Session Initiation Protocol (SIP) [RFC3311] Rosenberg, J., "The Session Initiation Protocol (SIP)
UPDATE Method", RFC 3311, October 2002. UPDATE Method", RFC 3311, October 2002.
[RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private [RFC3325] Jennings, C., Peterson, J., and M. Watson, "Private
Extensions to the Session Initiation Protocol (SIP) for Extensions to the Session Initiation Protocol (SIP) for
Asserted Identity within Trusted Networks", RFC 3325, Asserted Identity within Trusted Networks", RFC 3325,
November 2002. November 2002.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
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[RFC5168] Levin, O., Even, R., and P. Hagendorf, "XML Schema for [RFC5168] Levin, O., Even, R., and P. Hagendorf, "XML Schema for
Media Control", RFC 5168, March 2008. Media Control", RFC 5168, March 2008.
[RFC5630] Audet, F., "The Use of the SIPS URI Scheme in the Session [RFC5630] Audet, F., "The Use of the SIPS URI Scheme in the Session
Initiation Protocol (SIP)", RFC 5630, October 2009. Initiation Protocol (SIP)", RFC 5630, October 2009.
[RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and [RFC5761] Perkins, C. and M. Westerlund, "Multiplexing RTP Data and
Control Packets on a Single Port", RFC 5761, April 2010. Control Packets on a Single Port", RFC 5761, April 2010.
[RFC6222] Begen, A., Perkins, C., and D. Wing, "Guidelines for
Choosing RTP Control Protocol (RTCP) Canonical Names
(CNAMEs)", RFC 6222, April 2011.
[RFC6263] Marjou, X. and A. Sollaud, "Application Mechanism for [RFC6263] Marjou, X. and A. Sollaud, "Application Mechanism for
Keeping Alive the NAT Mappings Associated with RTP / RTP Keeping Alive the NAT Mappings Associated with RTP / RTP
Control Protocol (RTCP) Flows", RFC 6263, June 2011. Control Protocol (RTCP) Flows", RFC 6263, June 2011.
[RFC6341] Rehor, K., Portman, L., Hutton, A., and R. Jain, "Use [RFC6341] Rehor, K., Portman, L., Hutton, A., and R. Jain, "Use
Cases and Requirements for SIP-Based Media Recording Cases and Requirements for SIP-Based Media Recording
(SIPREC)", RFC 6341, August 2011. (SIPREC)", RFC 6341, August 2011.
[RFC7022] Begen, A., Perkins, C., Wing, D., and E. Rescorla,
"Guidelines for Choosing RTP Control Protocol (RTCP)
Canonical Names (CNAMEs)", RFC 7022, September 2013.
Authors' Addresses Authors' Addresses
Leon Portman Leon Portman
NICE Systems NICE Systems
8 Hapnina 22 Zarhin Street
Ra'anana 43017 P.O. Box 690
Ra'anana 4310602
Israel Israel
Email: leon.portman@nice.com Email: leon.portman@gmail.com
Henry Lum (editor) Henry Lum (editor)
Genesys Genesys
1380 Rodick Road, Suite 201 1380 Rodick Road, Suite 201
Markham, Ontario L3R4G5 Markham, Ontario L3R4G5
Canada Canada
Email: henry.lum@genesyslab.com Email: henry.lum@genesyslab.com
Charles Eckel Charles Eckel
Cisco Cisco
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
United States United States
Email: eckelcu@cisco.com Email: eckelcu@cisco.com
Alan Johnston Alan Johnston
Avaya Avaya
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Email: eckelcu@cisco.com Email: eckelcu@cisco.com
Alan Johnston Alan Johnston
Avaya Avaya
St. Louis, MO 63124 St. Louis, MO 63124
Email: alan.b.johnston@gmail.com Email: alan.b.johnston@gmail.com
Andrew Hutton Andrew Hutton
Siemens Enterprise Communications Unify
Brickhill Street Brickhill Street
Milton Keynes MK15 0DJ Milton Keynes MK15 0DJ
United Kingdom United Kingdom
Email: andrew.hutton@siemens-enterprise.com Email: andrew.hutton@unify.com
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