draft-ietf-siprec-protocol-02.txt   draft-ietf-siprec-protocol-03.txt 
SIPREC L. Portman, Ed. SIPREC L. Portman, Ed.
Internet-Draft NICE Systems Internet-Draft NICE Systems
Intended status: Standards Track H. Lum, Ed. Intended status: Standards Track H. Lum, Ed.
Expires: May 3, 2012 Genesys, Alcatel-Lucent Expires: September 8, 2012 Genesys
A. Johnston A. Johnston
Avaya Avaya
A. Hutton A. Hutton
Siemens Enterprise Siemens Enterprise
Communications Communications
October 31, 2011 March 07, 2012
Session Recording Protocol Session Recording Protocol
draft-ietf-siprec-protocol-02 draft-ietf-siprec-protocol-03
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) from the Session Recording Client establish a Recording Session (RS) between the Session Recording
(SRC), which is on the path of the CS, to a Session Recording Server Client (SRC), which is on the path of the CS, and a Session Recording
(SRS) at the recording device. Server (SRS) at the recording device.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 3, 2012. This Internet-Draft will expire on September 8, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 27 skipping to change at page 2, line 27
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Overview of operations . . . . . . . . . . . . . . . . . . . . 5 4. Overview of operations . . . . . . . . . . . . . . . . . . . . 5
4.1. Delivering recorded media . . . . . . . . . . . . . . . . 5 4.1. Delivering recorded media . . . . . . . . . . . . . . . . 5
4.2. Delivering recording metadata . . . . . . . . . . . . . . 7 4.2. Delivering recording metadata . . . . . . . . . . . . . . 7
5. Initiating a Recording Session . . . . . . . . . . . . . . . . 8 5. Initiating a Recording Session . . . . . . . . . . . . . . . . 8
5.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 8 5.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 8
5.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 9 5.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 9
6. SDP Handling . . . . . . . . . . . . . . . . . . . . . . . . . 9 6. SDP Handling . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 10 6.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 9
6.1.1. Handling media stream updates . . . . . . . . . . . . 11 6.1.1. Handling media stream updates . . . . . . . . . . . . 11
6.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 12 6.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 11
7. RTP Handling . . . . . . . . . . . . . . . . . . . . . . . . . 13 7. RTP Handling . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. Metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. Metadata . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
8.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 13 8.1. Procedures at the SRC . . . . . . . . . . . . . . . . . . 12
8.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 15 8.2. Procedures at the SRS . . . . . . . . . . . . . . . . . . 14
8.2.1. Formal Syntax . . . . . . . . . . . . . . . . . . . . 17 8.2.1. Formal Syntax . . . . . . . . . . . . . . . . . . . . 16
9. Persistent Recording . . . . . . . . . . . . . . . . . . . . . 17 9. Persistent Recording . . . . . . . . . . . . . . . . . . . . . 16
10. Extensions for Recording-aware User Agents . . . . . . . . . . 17 10. Extensions for Recording-aware User Agents . . . . . . . . . . 16
10.1. Procedures at the record-aware user agent . . . . . . . . 17 10.1. Procedures at the record-aware user agent . . . . . . . . 17
10.1.1. Recording preference . . . . . . . . . . . . . . . . . 18 10.1.1. Recording preference . . . . . . . . . . . . . . . . . 17
10.2. Procedures at the SRC . . . . . . . . . . . . . . . . . . 19 10.2. Procedures at the SRC . . . . . . . . . . . . . . . . . . 18
10.2.1. Recording indication . . . . . . . . . . . . . . . . . 19 10.2.1. Recording indication . . . . . . . . . . . . . . . . . 18
10.2.2. Recording preference . . . . . . . . . . . . . . . . . 20 10.2.2. Recording preference . . . . . . . . . . . . . . . . . 20
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
11.1. Registration of Option Tags . . . . . . . . . . . . . . . 21 11.1. Registration of Option Tags . . . . . . . . . . . . . . . 20
11.1.1. siprec Option Tag . . . . . . . . . . . . . . . . . . 21 11.1.1. siprec Option Tag . . . . . . . . . . . . . . . . . . 20
11.1.2. record-aware Option Tag . . . . . . . . . . . . . . . 21 11.1.2. record-aware Option Tag . . . . . . . . . . . . . . . 20
11.2. Registration of media feature tags . . . . . . . . . . . . 21 11.2. Registration of media feature tags . . . . . . . . . . . . 20
11.2.1. src feature tag . . . . . . . . . . . . . . . . . . . 21 11.2.1. src feature tag . . . . . . . . . . . . . . . . . . . 21
11.2.2. srs feature tag . . . . . . . . . . . . . . . . . . . 22 11.2.2. srs feature tag . . . . . . . . . . . . . . . . . . . 21
11.3. New Content-Disposition Parameter Registrations . . . . . 22 11.3. New Content-Disposition Parameter Registrations . . . . . 22
11.4. Media Type Registration . . . . . . . . . . . . . . . . . 22 11.4. Media Type Registration . . . . . . . . . . . . . . . . . 22
11.4.1. Registration of MIME Type application/rs-metadata . . 22 11.4.1. Registration of MIME Type application/rs-metadata . . 22
11.4.2. Registration of MIME Type 11.4.2. Registration of MIME Type
application/rs-metadata-request . . . . . . . . . . . 23 application/rs-metadata-request . . . . . . . . . . . 22
11.5. SDP Attributes . . . . . . . . . . . . . . . . . . . . . . 23 11.5. SDP Attributes . . . . . . . . . . . . . . . . . . . . . . 22
11.5.1. 'record' SDP Attribute . . . . . . . . . . . . . . . . 23 11.5.1. 'record' SDP Attribute . . . . . . . . . . . . . . . . 22
11.5.2. 'recordpref' SDP Attribute . . . . . . . . . . . . . . 23 11.5.2. 'recordpref' SDP Attribute . . . . . . . . . . . . . . 23
12. Security Considerations . . . . . . . . . . . . . . . . . . . 24 12. Security Considerations . . . . . . . . . . . . . . . . . . . 23
12.1. Authentication and Authorization . . . . . . . . . . . . . 24 12.1. Authentication and Authorization . . . . . . . . . . . . . 23
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 24
14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24
14.1. Normative References . . . . . . . . . . . . . . . . . . . 24 14.1. Normative References . . . . . . . . . . . . . . . . . . . 24
14.2. Informative References . . . . . . . . . . . . . . . . . . 25 14.2. Informative References . . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25
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) from the Session Recording Client (SRC), which is on the Session (RS) between the Session Recording Client (SRC), which is on
path of the CS, to a Session Recording Server (SRS) at the recording the path of the CS, and a Session Recording Server (SRS) at the
device. recording device.
SIP is also used to deliver metadata to the recording device, as SIP is also used to deliver metadata to the recording device, as
specified in [I-D.ietf-siprec-metadata]. Metadata is information specified in [I-D.ietf-siprec-metadata]. Metadata is information
that describes recorded media and the CS to which they relate. that describes recorded media and the CS to which they relate.
The Session Recording Protocol intends to satisfy the SIP-based Media The Session Recording Protocol intends to satisfy the SIP-based Media
Recording requirements listed in [RFC6341]. Recording requirements listed in [RFC6341].
2. Definitions 2. Definitions
skipping to change at page 6, line 45 skipping to change at page 6, line 45
conference with a mixer. For clarity, ACKs to INVITEs and 200 OKs to conference with a mixer. For clarity, ACKs to INVITEs and 200 OKs to
BYEs are not shown. The conference focus can provide the SRC BYEs are not shown. The conference focus can provide the SRC
functionality since the conference focus has access to all the media functionality since the conference focus has access to all the media
from each conference participant. When a recording is requested, the from each conference participant. When a recording is requested, the
SRC delivers the metadata and the media streams to the SRS. Since SRC delivers the metadata and the media streams to the SRS. Since
the conference focus has access to a mixer, the SRC may choose to mix the conference focus has access to a mixer, the SRC may choose to mix
the media streams from all participants as a single mixed media the media streams from all participants as a single mixed media
stream towards the SRS. stream towards the SRS.
An SRC can use a single recording session to record multiple An SRC can use a single recording session to record multiple
communication sessions. Every time the SRC wants record a new call, communication sessions. Every time the SRC wants to record a new
the SRC updates the recording session with a new SDP offer to add new call, the SRC updates the recording session with a new SDP offer to
recorded streams to the recording session, and correspondingly also add new recorded streams to the recording session, and
update the metadata for the new call. correspondingly also update the metadata for the new call.
4.2. Delivering recording metadata 4.2. Delivering recording metadata
The SRC is responsible for the delivery of metadata to the SRS. The The SRC is responsible for the delivery of metadata to the SRS. The
SRC may provide an initial metadata snapshot about recorded media SRC may provide an initial metadata snapshot about recorded media
streams in the initial INVITE content in the recording session. streams in the initial INVITE content in the recording session.
Subsequent metadata updates can be represented as a stream of events Subsequent metadata updates can be represented as a stream of events
in UPDATE or reINVITE requests sent by the SRC. These metadata in UPDATE or reINVITE requests sent by the SRC. These metadata
updates are normally incremental updates to the initial metadata updates are normally incremental updates to the initial metadata
snapshot to optimize on the size of updates, however, the SRC may snapshot to optimize on the size of updates, however, the SRC may
skipping to change at page 8, line 44 skipping to change at page 8, line 44
| (14) 200 OK | | (14) 200 OK |
|<----------------------------------------------------| |<----------------------------------------------------|
Figure 3: Delivering metadata via SIP UPDATE Figure 3: Delivering metadata via SIP UPDATE
5. Initiating a Recording Session 5. Initiating a Recording Session
5.1. Procedures at the SRC 5.1. Procedures at the SRC
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. In this case, the From header MUST contain the request to the SRS. The SRC and the SRS are identified in the From
identity of the SRC, and the To header MUST contain the identity of and To headers, respectively.
the SRS. Participants information is not recorded in the From or To
header; they are included in the metadata.
The SRC MUST include the '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 'src' feature recording sessions. An SRS uses the presence of the '+sip.src'
tag in dialog creating and modifying requests and responses to feature tag in dialog creating and modifying requests and responses
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, a registrar could discover that a UA Recording Session. In addition, when an SRC sends a REGISTER request
is an SRC based on the presence of this feature tag in a to a registrar, the SRC MUST include the '+sip.src' feature tag to
registration. Other SIP Recording extensions and behaviors can be indicate the that it is a SRC.
triggered by the presence of this feature tag.
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 SHOULD include the option tag in a recording session. An SRC MUST include the "siprec"
"siprec" option tag in the Require header when initiating a Recording option tag in the Require header when initiating a Recording Session
Session so that other types of user agents can simply reject the so that UA's which do not support the session recording protocol
INVITE request with a 420 Bad Extension. extensions will simply reject the INVITE request with a 420 Bad
Extension.
5.2. Procedures at the SRS 5.2. Procedures at the SRS
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. In this case, the From header MUST contain the request to the SRC. The SRS and the SRC are identified in the From
identity of the SRS, and the To header MUST contain the identity of and To headers, respectively.
the SRC.
The SRS MUST include the 'srs' feature tag in the Contact URI, as per The SRS MUST include the '+sip.srs' feature tag in the Contact URI,
[RFC3840], for all recording sessions. An SRC uses the presence of as per [RFC3840], for all recording sessions. An SRC uses the
this feature tag in dialog creating and modifying requests and presence of this feature tag in dialog creating and modifying
responses to confirm that the dialog being created is for the purpose requests and responses to confirm that the dialog being created is
of a Recording Session (REQ-30). In addition, a registrar could for the purpose of a Recording Session (REQ-30). In addition, when
discover that a UA is an SRS based on the presence of this feature an SRS sends a REGISTER request to a registrar, the SRS MUST include
tag in a registration. Other SIP Recording extensions and behaviors the '+sip.srs' feature tag to indicate that it is a SRS.
can be triggered by the presence of this feature tag.
An SRS SHOULD include the "siprec" option tag in the Require header An SRS MUST include the "siprec" option tag in the Require header as
as per [RFC3261] when initiating a Recording Session so that other per [RFC3261] when initiating a Recording Session so that UA's which
types of user agents can simply reject the INVITE request with a 420 do not support the session recording protocol extensions will simply
Bad Extension. reject the INVITE request with a 420 Bad Extension.
6. SDP Handling 6. SDP Handling
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
rest of this section describes conventions used in a recording rest of this section describes conventions used in a recording
session. session.
6.1. Procedures at the SRC 6.1. Procedures at the SRC
Since the SRC does not expect to receive media from the SRS, the SRC Since the SRC does not expect to receive media from the SRS, the SRC
typically sets each media stream of the SDP offer to only send media, typically sets each media stream of the SDP offer to only send media,
by qualifying them with the a=sendonly attribute, according to the by qualifying them with the a=sendonly attribute, according to the
procedures in [RFC3264]. procedures in [RFC3264].
The SRC sends recorded streams of participants to the SRS, and the The SRC sends recorded streams of participants to the SRS, and the
SRC MUST provide a label attribute (a=label), as per [RFC4574], on SRC MUST provide a label attribute (a=label), as per [RFC4574], on
each media stream in order to identify the recorded stream with the each media stream in order to identify the recorded stream with the
rest of the metadata. The a=label attribute identifies each recorded rest of the metadata. The a=label attribute identifies each recorded
media stream, and the label name is mapped to the Media Stream media stream, and the label name is mapped to the Media Stream
Reference in the metadata in [I-D.ietf-siprec-metadata]. Note that a Reference in the metadata as per [I-D.ietf-siprec-metadata]. The
recorded stream is different than a CS stream; the metadata provides scope of the label name only applies to the same SIP message as the
a list of participants that contributes to each recorded stream. SDP, meaning that the label name can be reused by another media
stream within the same recording session. Note that a recorded
stream is distinct from a CS stream; the metadata provides a list of
participants that contributes to each recorded stream.
The following is an example of SDP with both audio and video recorded The following is an example of SDP with both audio and video recorded
streams. Note that the following example contain unfolded lines streams. Note that the following example contain unfolded lines
longer than 72 characters. These are captured between <allOneLine> longer than 72 characters. These are captured between <allOneLine>
tags. tags.
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=-
c=IN IP4 198.51.100.1 c=IN IP4 198.51.100.1
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The SRS only receives RTP streams from the SRC, the SDP answer The SRS only receives RTP streams from the SRC, the SDP answer
normally sets each media stream to receive media, by setting them normally sets each media stream to receive media, by setting them
with the a=recvonly attribute, according to the procedures of with the a=recvonly attribute, according to the procedures of
[RFC3264]. When the SRS is not ready to receive a recorded stream, [RFC3264]. When the SRS is not ready to receive a recorded stream,
the SRS sets the media stream as inactive in the SDP offer or answer the SRS sets the media stream as inactive in the SDP offer or answer
by setting it with a=inactive attribute, according to the procedures by setting it with a=inactive attribute, according to the procedures
of [RFC3264]. When the SRS is ready to receive recorded streams, the of [RFC3264]. When the SRS is ready to receive recorded streams, the
SRS sends a new SDP offer and sets the media streams with a=recvonly SRS sends a new SDP offer and sets the media streams with a=recvonly
attribute. attribute.
Over the lifetime of a recording session, the SRS can remove recorded
streams from the recording session for various reasons. To remove a
recorded stream from the recording session, the SRS sends a new SDP
offer where the port of the media stream to be removed is set to
zero, according to the procedures in [RFC3264].
The following sequence diagram shows an example where the SRS is The following sequence diagram shows an example where the SRS is
initially not ready to receive recorded streams, and later updates initially not ready to receive recorded streams, and later updates
the recording session when the SRS is ready to record. the recording session when the SRS is ready to record.
SRC SRS SRC SRS
| | | |
|(1) INVITE (SDP offer) | |(1) INVITE (SDP offer) |
|---------------------------------------------------->| |---------------------------------------------------->|
| [not ready to record] | [not ready to record]
| (2)200 OK with SDP inactive | | (2)200 OK with SDP inactive |
skipping to change at page 13, line 30 skipping to change at page 12, line 30
| (6) ACK | | (6) ACK |
|<----------------------------------------------------| |<----------------------------------------------------|
|(7) RTP | |(7) RTP |
|====================================================>| |====================================================>|
| ... | | ... |
|(8) BYE | |(8) BYE |
|---------------------------------------------------->| |---------------------------------------------------->|
| (9) OK | | (9) OK |
|<----------------------------------------------------| |<----------------------------------------------------|
Figure 5: SRS to offer with a=inactive Figure 5: SRS responding to offer with a=inactive
7. RTP Handling 7. RTP Handling
This is a placeholder section to specify any protocol impacts or This is a placeholder section to specify any protocol impacts or
recommendations for RTP usage in the session recording protocol. The recommendations for RTP usage in the session recording protocol. The
details are listed in [I-D.eckel-siprec-rtp-rec] details are listed in [I-D.eckel-siprec-rtp-rec]
8. Metadata 8. Metadata
8.1. Procedures at the SRC 8.1. Procedures at the SRC
skipping to change at page 14, line 16 skipping to change at page 13, line 16
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. When the SRC sends a full metadata snapshot, the SRC MUST
send an INVITE request with an SDP offer and the "recording-session" send an INVITE or an UPDATE request with an SDP offer and the
disposition. A partial update represents an incremental update since "recording-session" disposition. A partial update represents an
the last metadata update sent by the SRC. A partial update sent by incremental update since the last metadata update sent by the SRC. A
the SRC can be an INVITE request or response with an SDP offer, or an partial update sent by the SRC can be an INVITE request or response
INVITE/UPDATE request or response containing a "recording-session" with an SDP offer, or an INVITE/UPDATE request or response containing
disposition, or an INVITE request containing both an SDP offer and a "recording-session" disposition, or an INVITE request containing
the "recording-session" disposition. both an SDP offer and the "recording-session" disposition.
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-098392474 From: <sip:2000@example.com>;tag=35e195d2-947d-4585-946f-098392474
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,
application/rs-metadata-request application/rs-metadata-request
Contact: <sip:2000@src.example.com>;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=-
c=IN IP4 198.51.100.1 c=IN IP4 198.51.100.1
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previous update, the SRS needs to keep track of the sequence of previous update, the SRS needs to keep track of the sequence of
updates from the SRC. updates from the SRC.
In the case of an internal failure at the SRS, the SRS may fail to In the case of an internal failure at the SRS, the SRS may fail to
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 syntax errors or snapshot from the SRC. Certain errors, such 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, it is RECOMMENDED that the SRS avoid repeating the same error, the SRS can simply terminate the
terminate the recording session when a syntax error or semantic error recording session when a syntax error or semantic error is detected
is detected in the metadata. in the metadata.
When the SRS requires a full metadata snapshot, the SRS sends a When the SRS explicitly requests for a full metadata snapshot, the
metadata snapshot request to the SRC in an INVITE/UPDATE request or SRS MUST send an UPDATE request without an SDP offer. A metadata
in an INVITE/UPDATE response. The metadata snapshot request is snapshot request contains a content with the content disposition type
contained the content with the disposition type "recording-session". "recording-session". Note that the SRS MAY generate an INVITE
The format of the content is "application/rs-metadata-request", and request without an SDP offer but this MUST not include a metadata
the body format is chosen to be a simple text-based format. The snapshot request. The format of the content is "application/
following shows an example: rs-metadata-request", and the body format is chosen to be a simple
text-based format. The 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>;srs Contact: <sip:recorder@srs.example.com>;+sip.srs
Accept: appliation/sdp, application/rs-metadata Accept: appliation/sdp, application/rs-metadata
Content-Disposition: recording-session Content-Disposition: recording-session
Content-Type: application/rs-metadata-request Content-Type: application/rs-metadata-request
Content-Length: [length] Content-Length: [length]
SRS internal error SRS internal error
Figure 7: Metadata Request Figure 7: 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 the request for a metadata snapshot, the SRC
MUST provide a full metadata snapshot in a separate INVITE MUST provide a full metadata snapshot in a separate INVITE or UPDATE
transaction, along with an SDP offer. All subsequent metadata transaction, along with an SDP offer. All subsequent metadata
updates sent by the SRC MUST be based on the new metadata snapshot. updates sent by the SRC MUST be based on the new metadata snapshot.
8.2.1. Formal Syntax 8.2.1. 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 [RFC2234]. described in [RFC2234].
snapshot-request = srs-reason-line CRLF snapshot-request = srs-reason-line CRLF
srs-reason-line = [TEXT-UTF8-TRIM] srs-reason-line = [TEXT-UTF8-TRIM]
9. Persistent Recording 9. 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
sends recorded media to the SRS in the absence of a CS for certain records media in a recording session to the SRS even in the absence
allocated devices; allocated devices can include a specific physical of a CS for all user agents that are part of persistent recording.
device, a specific person or contact registered, or a set of trunks By allocating recorded streams and continuously sending recorded
or ports of a gateway. To continuously record, the SRC adds recorded media to the SRS, the SRC does not have to prepare new recorded
streams into the recording session for all devices with persistent streams with new SDP offer when a new communication session is
recording. By allocating recorded streams and continuously sending created and also does not impact the timing of the CS. The SRC only
recorded media to the SRS, the SRC does not have to prepare new needs to update the metadata when new communication sessions are
recorded streams with new SDP offer when a new communication session
is created and also does not impact the timing of the CS. The SRC
only needs to update the metadata when new communication sessions are
created. created.
When there is no communication sessions running on the devices with When there is no communication sessions running on the devices with
persistent recording, there is no recorded media to stream from the persistent recording, there is no recorded media to stream from the
SRC to the SRS. In certain environments where Network Address SRC to the SRS. In certain environments where Network Address
Translator (NAT) is used, typically a minimum of flow activity is Translator (NAT) is used, typically a minimum of flow activity is
required to maintain the NAT binding for each port opened. In order required to maintain the NAT binding for each port opened. Agents
not to lose the NAT bindings for the RTP/RTCP ports opened for the that support Interactive Connectivity Establishment (ICE) solves this
recorded streams, the SRC and SRS SHOULD follow the recommendations problem. For non-ICE agents, in order not to lose the NAT bindings
provided in [RFC6263] to maintain the NAT bindings. for the RTP/RTCP ports opened for the recorded streams, the SRC and
SRS SHOULD follow the recommendations provided in [RFC6263] to
maintain the NAT bindings.
10. Extensions for Recording-aware User Agents 10. Extensions for Recording-aware User Agents
The following sections describe the SIP and SDP extensions for The following sections describe the SIP and SDP extensions for
recording-aware user agents. recording-aware user agents. A recording-aware user agent is a
participant in the CS that supports the SIP and SDP extensions for
receiving recording indication and for requesting recording
preferences for the call.
10.1. Procedures at the record-aware user agent 10.1. Procedures at the record-aware user agent
A recording-aware UA SHOULD indicate that it can accept reporting of A recording-aware UA SHOULD indicate that it can accept reporting of
recording indication provided by the SRC. A new option tag "record- recording indication provided by the SRC. A new option tag "record-
aware" is introduced to indicate such awareness. The recording-aware aware" is introduced to indicate such awareness. The recording-aware
UA SHOULD include the "record-aware" option tag in the Supported UA SHOULD include the "record-aware" option tag in the Supported
header when initiating or establishing a CS. A recording-aware UA header when initiating or establishing a CS. A recording-aware UA
that has indicated recording awareness MUST provide at recording that has indicated recording awareness MUST provide at recording
indication to the end user through an appropriate user interface an indication to the end user through an appropriate user interface an
skipping to change at page 18, line 28 skipping to change at page 17, line 34
recording awareness, thereby relying on whatever mechanism an SRC recording awareness, thereby relying on whatever mechanism an SRC
chooses to indicate recording, such as playing a tone inband. chooses to indicate recording, such as playing a tone inband.
10.1.1. Recording preference 10.1.1. Recording preference
A recording-aware UA involved in a CS MAY request the CS to be A recording-aware UA involved in a CS MAY request the CS to be
recorded or not recorded. This indication of recording preference recorded or not recorded. This indication of recording preference
can be sent at session establishment time or during the session. can be sent at session establishment time or during the session.
A new SDP attribute "recordpref" is introduced. The SDP attribute A new SDP attribute "recordpref" is introduced. The SDP attribute
appears at the media level and can appear in an SDP offer or answer. appears at the media level or session level and can appear in an SDP
The recording indication applies to the specified media stream only. offer or answer. The recording indication applies to the specified
The following is the ABNF of the recordpref attribute: media stream only. The following is the ABNF of the recordpref
attribute:
recordpref-attr = "a=recordpref:" pref recordpref-attr = "a=recordpref:" pref
pref = "on" / "off" / "pause" / "nopreference" pref = "on" / "off" / "pause" / "nopreference"
on Request for recording if it has not already been started. If the on Request for recording if it has not already been started. If the
recording is currently paused, request to resume recording. recording is currently paused, request to resume recording.
off Request for no recording. If recording has already been off Request for no recording. If recording has already been
started, then this preference indicates a request to stop started, then this preference indicates a request to stop
skipping to change at page 19, line 24 skipping to change at page 18, line 32
10.2.1. Recording indication 10.2.1. Recording indication
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 SDP attribute is introduced to allow a to the participants. A new SDP attribute is introduced to allow a
recording-aware UA to render recording indication at the user recording-aware UA to render recording indication at the user
interface. interface.
The 'record' SDP attribute appears at the media level in either SDP The 'record' SDP attribute appears at the media level or session
offer or answer. The recording indication applies to the specified level in either SDP offer or answer. The recording indication
media stream only, for example, only the audio portion of the call is applies to the specified media stream only, for example, only the
recorded in an audio/video call. The following is the ABNF of the audio portion of the call is recorded in an audio/video call. The
'record' attribute: 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 record-attr = "record:" indication
indication = "on" / "off" / "paused" 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 by media is paused. paused Recording is in progress by media is paused.
The recording attribute is a declaration by an endpoint in the CS to The recording attribute is a declaration by the SRC in the CS to
indicate whether recording is taking place. For example, if a UA (A) indicate whether recording is taking place. For example, if a UA (A)
is initiating a call to UA (B) and UA (A) is also an SRC that is is initiating a call to UA (B) and UA (A) is also an SRC that is
performing the recording, then UA (A) provides the recording performing the recording, then UA (A) provides the recording
indication in the SDP offer with a=record:on. When UA (B) receives indication in the SDP offer with a=record:on. When UA (B) receives
the SDP offer, UA (B) will see that recording is happening on the the SDP offer, UA (B) will see that recording is happening on the
other endpoint of this session. If UA (B) does not wish to perform other endpoint of this session. If UA (B) does not wish to perform
recording itself, UA (B) provides the recording indication as recording itself, UA (B) provides the recording indication as
a=record:off in the SDP answer. a=record:off in the SDP answer.
Whenever the recording indication needs to change, such as Whenever the recording indication needs to change, such as
termination of recording, then the UA MUST initiate a reINVITE to termination of recording, then the UA MUST initiate a reINVITE or
update the SDP attribute to a=record:off. The following call flow UPDATE to update the SDP attribute to a=record:off. The following
shows an example of the offer/answer with the recording indication call flow shows an example of the offer/answer with the recording
attribute. indication attribute.
UA A UA B UA A UA B
(SRC) | (SRC) |
| | | |
| [SRC recording starts] | | [SRC recording starts] |
|(1) INVITE (SDP offer + a=record:on) | |(1) INVITE (SDP offer + a=record:on) |
|---------------------------------------------------->| |---------------------------------------------------->|
| 200 OK (SDP answer) | | 200 OK (SDP answer) |
|<----------------------------------------------------| |<----------------------------------------------------|
|(3) ACK | |(3) ACK |
skipping to change at page 20, line 45 skipping to change at page 20, line 10
indication attribute does not provide any hint as to which SRC is indication attribute does not provide any hint as to which SRC is
performing the recording, meaning the endpoint only knows that the performing the recording, meaning the endpoint only knows that the
call is being recorded. This attribute is also not used as an call is being recorded. This attribute is also not used as an
indication to negotiate which SRC in the call path will perform indication to negotiate which SRC in the call path will perform
recording and is not used as a request to start/stop recording if recording and is not used as a request to start/stop recording if
there are multiple SRCs in the call path. there are multiple SRCs in the call path.
10.2.2. Recording preference 10.2.2. Recording preference
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 MAY choose to honor such request to record the request based the SRC chooses to honor such request to record the request based on
on local policy on the SRC. When the SRC honors the request, the SRC local policy on the SRC. When the SRC honors the request, the SRC
MUST also update the recording indication to reflect the current MUST also update the recording indication to reflect the current
state of the recording (on/off/paused). state of the recording (on/off/paused).
11. IANA Considerations 11. IANA Considerations
11.1. Registration of Option Tags 11.1. Registration of Option Tags
This specification registers two option tags. The required This specification registers two option tags. The required
information for this registration, as specified in [RFC3261], is as information for this registration, as specified in [RFC3261], is as
follows. follows.
skipping to change at page 21, line 28 skipping to change at page 20, line 38
for the purpose of recording session only. This is typically not for the purpose of recording session only. This is typically not
used in a Supported header. When present in a Require header in a used in a Supported header. When present in a Require header in a
request, it indicates that the UAS MUST be either a SRC or SRS request, it indicates that the UAS MUST be either a SRC or SRS
capable of handling the contexts of a recording session. capable of handling the contexts of a recording session.
11.1.2. record-aware Option Tag 11.1.2. record-aware Option Tag
Name: record-aware Name: record-aware
Description: This option tag is to indicate the ability for the Description: This option tag is to indicate the ability for the
user agent to receive recording indicators in media level SDP. user agent to receive recording indicators in media level or
When present in a Supported header, it indicates that the UA can session level SDP. When present in a Supported header, it
receive recording indicators in media level SDP. indicates that the UA can receive recording indicators in media
level or session level SDP.
11.2. Registration of media feature tags 11.2. Registration of media feature tags
This document registers two new media feature tags in the SIP tree This document registers two new media feature tags in the SIP tree
per the process defined in [RFC2506] and [RFC3840] per the process defined in [RFC2506] and [RFC3840]
11.2.1. src feature tag 11.2.1. src feature tag
Media feature tag name: sip.src Media feature tag name: sip.src
skipping to change at page 23, line 32 skipping to change at page 23, line 4
11.5. SDP Attributes 11.5. SDP Attributes
This document registers the following new SDP attributes. This document registers the following new SDP attributes.
11.5.1. 'record' SDP Attribute 11.5.1. 'record' SDP Attribute
Contact names: Leon Portman leon.portman@nice.com, Henry Lum Contact names: Leon Portman leon.portman@nice.com, Henry Lum
henry.lum@genesyslab.com henry.lum@genesyslab.com
Attribute name: record Attribute name: record
Long form attribute name: Recording Indication Long form attribute name: Recording Indication
Type of attribute: media level Type of attribute: session or media level
Subject to charset: no Subject to charset: no
This attribute provides the recording indication for the session or This attribute provides the recording indication for the session or
media stream. media stream.
Allowed attribute values: on, off, paused Allowed attribute values: on, off, paused
11.5.2. 'recordpref' SDP Attribute 11.5.2. 'recordpref' SDP Attribute
Contact names: Leon Portman leon.portman@nice.com, Henry Lum Contact names: Leon Portman leon.portman@nice.com, Henry Lum
henry.lum@genesyslab.com henry.lum@genesyslab.com
Attribute name: recordpref Attribute name: recordpref
Long form attribute name: Recording Preference Long form attribute name: Recording Preference
Type of attribute: media level
Type of attribute: session or media level
Subject to charset: no Subject to charset: no
This attribute provides the recording indication for the session or This attribute provides the recording indication for the session or
media stream. media stream.
Allowed attribute values: on, off, pause, nopreference Allowed attribute values: on, off, pause, nopreference
12. Security Considerations 12. Security Considerations
skipping to change at page 24, line 43 skipping to change at page 24, line 16
We want to thank John Elwell, Paul Kyzivat, Partharsarathi R, Ram We want to thank John Elwell, Paul Kyzivat, Partharsarathi R, Ram
Mohan R, Charles Eckel, Hadriel Kaplan, Adam Roach, Miguel Garcia for Mohan R, Charles Eckel, Hadriel Kaplan, Adam Roach, Miguel Garcia for
their valuable comments and inputs to this document. their valuable 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 Ravindran, P. and P. Kyzivat, "Session Initiation Protocol
Protocol (SIP) Recording Metadata", (SIP) Recording Metadata", draft-ietf-siprec-metadata-05
draft-ietf-siprec-metadata-05 (work in progress), (work in progress), October 2011.
October 2011.
[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.
[RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997. Specifications: ABNF", RFC 2234, November 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.
skipping to change at page 25, line 43 skipping to change at page 25, line 13
Protocol (SDP) Label Attribute", RFC 4574, August 2006. Protocol (SDP) Label Attribute", RFC 4574, August 2006.
[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.
14.2. Informative References 14.2. Informative References
[I-D.eckel-siprec-rtp-rec] [I-D.eckel-siprec-rtp-rec]
Eckel, C., "Real-time Transport Protocol (RTP) Eckel, C., "Real-time Transport Protocol (RTP)
Recommendations for SIPREC", draft-eckel-siprec-rtp-rec-02 Recommendations for SIPREC", draft-eckel-siprec-rtp-rec-03
(work in progress), September 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 Portman, L., Rehor, K., Jain, R., and A. Hutton, "An
Architecture for Media Recording using the Session Architecture for Media Recording using the Session
Initiation Protocol", draft-ietf-siprec-architecture-03 Initiation Protocol", draft-ietf-siprec-architecture-03
(work in progress), October 2011. (work in progress), October 2011.
[RFC4508] Levin, O. and A. Johnston, "Conveying Feature Tags with [RFC4508] Levin, O. and A. Johnston, "Conveying Feature Tags with
the Session Initiation Protocol (SIP) REFER Method", the Session Initiation Protocol (SIP) REFER Method",
RFC 4508, May 2006. RFC 4508, May 2006.
[RFC4579] Johnston, A. and O. Levin, "Session Initiation Protocol [RFC4579] Johnston, A. and O. Levin, "Session Initiation Protocol
(SIP) Call Control - Conferencing for User Agents", (SIP) Call Control - Conferencing for User Agents",
skipping to change at page 26, line 26 skipping to change at page 26, line 4
Authors' Addresses Authors' Addresses
Leon Portman (editor) Leon Portman (editor)
NICE Systems NICE Systems
8 Hapnina 8 Hapnina
Ra'anana 43017 Ra'anana 43017
Israel Israel
Email: leon.portman@nice.com Email: leon.portman@nice.com
Henry Lum (editor) Henry Lum (editor)
Genesys, Alcatel-Lucent Genesys
1380 Rodick Road, Suite 200 1380 Rodick Road, Suite 200
Markham, Ontario L3R4G5 Markham, Ontario L3R4G5
Canada Canada
Email: henry.lum@genesyslab.com Email: henry.lum@genesyslab.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 Siemens Enterprise Communications
Brickhill Street
Milton Keynes MK15 0DJ
United Kingdom
Email: andrew.hutton@siemens-enterprise.com Email: andrew.hutton@siemens-enterprise.com
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