SIPREC Ram Mohan. Ravindranath
Internet-Draft Parthasarathi. Ravindran
Intended status: Standards Track Paul. Kyzivat
Expires: July 24, 2011 Cisco Systems, Inc.
January 20, 2011
Session Initiation Protocol (SIP) Recording Metadata
draft-ram-siprec-metadata-03
Abstract
Session recording is a critical requirement in many communications
environments such as call centers and financial trading. In some of
these environments, all calls must be recorded for regulatory,
compliance, and consumer protection reasons. Recording of a session
is typically performed by sending a copy of a media stream to a
recording device. This document describes the metadata model as
viewed by Session Recording Server(SRS).
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 24, 2011.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Metadata Model . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Recording Metadata elements . . . . . . . . . . . . . . . . . 5
4.1. Recording Session . . . . . . . . . . . . . . . . . . . . 5
4.1.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 5
4.1.2. Associations . . . . . . . . . . . . . . . . . . . . . 6
4.2. Communication Session Group . . . . . . . . . . . . . . . 6
4.2.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 6
4.2.2. Associations . . . . . . . . . . . . . . . . . . . . . 6
4.3. Communication Session . . . . . . . . . . . . . . . . . . 7
4.3.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 7
4.3.2. Associations . . . . . . . . . . . . . . . . . . . . . 8
4.4. Participant . . . . . . . . . . . . . . . . . . . . . . . 8
4.4.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 9
4.4.2. Associations . . . . . . . . . . . . . . . . . . . . . 9
4.5. Media Stream . . . . . . . . . . . . . . . . . . . . . . . 10
4.5.1. Attributes . . . . . . . . . . . . . . . . . . . . . . 10
4.5.2. Associations . . . . . . . . . . . . . . . . . . . . . 11
4.6. Application Data . . . . . . . . . . . . . . . . . . . . . 11
5. Metadata Model Object Instances . . . . . . . . . . . . . . . 11
5.1. Use case 1: Basic Call . . . . . . . . . . . . . . . . . . 11
5.2. Use case 2: Basic Call with hold/resume . . . . . . . . . 12
5.3. Use case 3: Basic call with Transfer . . . . . . . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6.1. Connection Security . . . . . . . . . . . . . . . . . . . 15
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 16
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
Session recording is a critical requirement in many communications
environments such as call centers and financial trading. In some of
these environments, all calls must be recorded for regulatory,
compliance, and consumer protection reasons. Recording of a session
is typically performed by sending a copy of a media stream to a
recording device. This document focuses on the Recording metadata
which describes the communication session. The document describes a
metadata model as viewed by Session Recording Server, the
requirements for which are described in [I-D.ietf-siprec-req] and the
architecture for which is described in
[I-D.ietf-siprec-architecture].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. This
document only uses these key words when referencing normative
statements in existing RFCs."
3. Metadata Model
Metadata is the data that describes the communication session. Below
diagram shows a model for Metadata as viewed by Session Recording
Server (SRS).
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+-------------------------------+ 1
| Recording Session (RS) |---------------+
+-------------------------------+ |
| 1..* |
| |
| 0..* |
+-------------------------------+ |
| Communication Session (CS) | 1 |
| Group |---------------|
+-------------------------------+ |
| 1 |
| |
| 1..* |
+-------------------------------+ |
| Communication Session (CS) | 1 |
| |---------------|
+-------------------------------+ | +------------+
| 0..* |1..* | | |
| | | 0..* |Application |
| 2..* |0..* |-------| Data |
+-------------+ receives +----------------+ | | |
| Participant |----------| Media Streams | | +------------+
| |0..* 0..*| | |
| | | | |
| | | | |
| | sends | | |
| |----------| | |
| |1.* 0..*| | |
+-------------+ +----------------+ |
| | |
|1 |1 |
| | |
+----------------------------------------+
The mechanism MUST provide a means to convey every attribute
mentioned in the metamodel. The Session Recording Client (SRC) MAY
initiate the Recording Session. It should be noted that the
Recording Session is a completely independent from the Communication
Session that is being recorded at both the SIP dialog level and at
the session level. The metadata MUST be conveyed from SRC to SRS.
The metadata MAY be conveyed in Recording Session Dialog.
Note that the metadata model captures changes that occur over the
duration of the recording session. For example, if the call is
transferred from one participant to another, then the SRC SHALL
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convey a change of participant and the properties of the new media
stream to the SRS.
Some of the data in the model may not be conveyed explicitly from the
SRC to the SRS, if it can be obtained contextually by the SRS. For
instance, the timing of changes may not explicitly conveyed from the
SRC to the SRC, because the mechanism (yet to be defined) which
conveys the metadata may implicitly provide the timing. (E.g. the
time a change occurred by be assumed to be the same as the time when
notification of the change is received by the SRS.)
4. Recording Metadata elements
This section describes the different elements and its attributes of
the metadata model shown above. This section also describes in brief
on how the different elements of metadata are associated.
4.1. Recording Session
+-------------------------------+
| Recording Session (RS) |
+-------------------------------+
| Recording RequestorID(SRC or | +-----------------+
| SRS) | 1 0..* | |
| |------------|Application Data |
| Recording Type (Selective | | |
| Persistant) | +-----------------+
+-------------------------------+
| 1..*
|
| 0..*
Communication Session Group(CS Group)
A Recording Session element represents one instance of a Recording
Session.
4.1.1. Attributes
A Recording Session element MAY have attributes like:
o Recording requestor ID(which could be SRS or SRC).
o Recording type - This attribute indicates whether the recording
session is selective or persistent.
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4.1.2. Associations
One instance of Recording Session SHALL have:
o Zero or more instances of Communication Session Group.This is to
accommodate persistent recording cases.
o Each CS Group MUST be associated with one or more Recording
Sessions [ setup by the same SRC.]
4.2. Communication Session Group
Recording Session (RS)
| 1..*
|
| 0..*
+-------------------------------+
| Communication Session |
| Group |
+-------------------------------+
| Unique-ID | +----------------+
| | 1 0..* | |
| |-----------|Application Data|
| | | |
+-------------------------------+ +----------------+
| 1
|
| 1..*
Communication Session (CS)
A Communication Session Group provides association or linking of
Communication Sessions.
4.2.1. Attributes
A CS Group MUST have a Unique-ID attribute. SRC (or MAY be SRS) MUST
ensure the uniqueness of Unique-ID in case multiple SRC interacts
with the same SRS. The mechanism by which SRC creates this unique-ID
and ensures its uniqueness is outside the scope of SIPREC.
NOTE: Need more clarity/use cases on how the unique-ID SHALL be used
4.2.2. Associations
A communication Session Group SHALL be associated with RS and CS in
the following manner:
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o There can be one or more Recording Session elements per
Communication Session Group.
o Each Communication Session Group MUST be associated with one or
more RS [ setup by the same SRC]
o There MAY be one or more Communication Sessions per CS Group [e.g.
Consult Transfer]
o Each CS MUST be associated to one CS-Group
4.3. Communication Session
Communication Session Group(CS Group)
| 1
|
| 1..*
+-------------------------------+ +-----------------+
| Communication Session (CS) | 1 0..* | |
| |---------------|Application Data |
+-------------------------------+ | |
| | +-----------------+
| Call Termination Reason |
| Force Deletion |
+-------------------------------+
| |
| 0..* |1..*
| |
| 2..* |0..*
Participant Media Stream
A Communication Session block/element in the metadata model
represents Communication Session and its properties needed as seen by
SRC.
4.3.1. Attributes
A communication Session block SHALL have the following attributes:
o Call Termination Reason - This represents the reason why a CS was
terminated. This MAY be derived from SIP Reason header of CS.
call termination reason MUST be optional and MAY be included in
metadata after the call is terminated.
NOTE: Attributes like Retention (represent the value/duration for
which Media streams of the CS needs to be retained), Access
Information e.t.c that are primarily related to policy will not be
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passed in metadata from SRC to SRS. However if there are
implementations where SRC has enough information, this could be sent
as App Data attached to CS
4.3.2. Associations
A Communication Session SHALL be associated to CS-Group,Participant
and Media Stream. Cardinalities between CS and Participant allows:
o CS to have atleast two or more participants
o Participant may be associated with zero or more CS's (It is
possible, though unlikely, that there are participants who are not
part of any CS). An example of such a case is participants in a
premixed media stream. The SRC may have knowledge of such
Participants, yet not have any signaling relationship with them.
This might arise if one participant in CS is a conf focus.
Another use case is if one UA in CS works in 3pcc mode to acquire
an MoH media stream, this might be reflected as unique source for
media stream without having a reported signaling relationship to
it.
o The model also allows participants in CS that are not participants
in the media. An example is the identity of a 3pcc controller
that has initiated a CS to two or more participants of the CS.
Another example is the identity of a conference focus. Of course
a focus is probably in the media, but since it may only be there
as a mixer, it may not report itself as a participant in any of
the media streams.
Cardinalities between CS and Media Stream allows:
o A CS to have zero or more Streams
o A stream can be associated with 1 or more CS. An example is
multicast MoH stream which might be associated with many CSs.
Also if we were to consider a B2BUA to have a separate CS on each
"side" then they might share a stream.(Though more likely this
would be treated as a single CS.)
4.4. Participant
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Communication Session (CS)
| 0..*
|
| 2..*
+-------------------------------+
| Participant |
| |
+-------------------------------+
| AoR list | +-----------------+
| Name | 1 0..* | |
| Participant Type |------------|Application Data |
| | | |
+-------------------------------+ +-----------------+
| 0..* 1..*|
receives| |sends
| 0..* 0..*|
Media Stream
A Participant block has information about user who is part of CS.
4.4.1. Attributes
Participant has attributes like:
o AoR list - Has list of AoRs. An AoR MAY be SIP/SIPS/TEL URI.
There MAY be cases where a participant can have more than one AoR
[ e.g. P-Asserted-ID which can have both SIP and TEL URIs]
o Name - This attribute represents Participant name(SIP display
name) or DN number ( in case it is known)
o Participant Type - This attribute can have values as "internal" or
"external" or "don't know" (in cases where it is not possible to
determine).
OPEN ITEM: Need to conclude on what other attributes [ like
Participant Role ] are needed to be represented in the model
4.4.2. Associations
Cardinalities between participant and Media Stream allows:
o Participant to receives zero or more media streams
o Participant to send zero or more media streams. (Same participant
provides multiple streams e.g. audio and video)
o Media stream to be received by zero or more participants. Its
possible, though perhaps unlikely, that a stream is generated but
sent only to the SRC and SRS, not to any participant. E.g. In
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conferencing where all participants are on hold and the SRC is
collocated with the focus. Also a media stream may be received by
multiple participants (e.g. Whisper calls, side conversations).
o Media stream to be sent by one or more participants (pre-mixed
streams).
NOTE: Example of a case where a participant may receive Zero or more
streams - a Supervisor may have side conversation with Agent, while
Agent converses with customer.
4.5. Media Stream
Participant
| 0..* 1..*|
receives| |sends
| 0..* 0..*|
+-------------------------+
| Media Stream |
| |
Communication 1..* 0..* +-------------------------+
Session ------------| Start Time | +--------+
| End Time |1 0..* | |
| Codec params |--------|Appl |
| Media Stream Reference | | Data |
+-------------------------+ +--------+
A Media Stream block shall have properties of media as seen by SRC
and sent to SRS. Different instances of Media Stream block would be
created whenever there is a change in media (e.g. dir change like
pause/resume and/or codec change and/or participant change.).
4.5.1. Attributes
A Media Stream block SHALL have the following attributes:
o Start Time - Represents Media Start time at SRC.
o End Time - Represents Media End time at SRC. This is an optional
attribute and MAY be included after a stream ends
o Codec params - represents codec parameters of the CS media
o Media Stream Reference - In implementations this can reference to
m-line
OPEN ITEM: Is it required to model media streams that are not
recorded[ e.g SRC offered certain media types but SRS choose to
accept only subset of them] ?
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4.5.2. Associations
A Media Stream SHALL be associated with Participant and CS. The
details of association with the Participant are described in the
Participant block section. The details of association with CS is
mentioned in the CS section.
4.6. Application Data
A recording metadata object MAY have a opaque application data. This
opaque data is intended to be used by vendor specific applications on
SRS.
5. Metadata Model Object Instances
This section describes the metadata model object instances for
different use cases of SIPREC. For the sake of simplicity as the
media streams sent by each of the participants is received by every
other participant in these use cases, it is NOT shown in the object
instance diagrams below.
5.1. Use case 1: Basic Call
Basic call between two Participants A and B. In this use case each
participant sends one Media Stream.
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+-------------------------------+
| Recording Session (RS) |
+-------------------------------+
|
|
|
+-------------------------------+
| Communication Session (CS) |
| Group(CSG) |
+-------------------------------+
| Unique-id1 |
+-------------------------------+
|
|
|
+----------------+
| Communication |
| Session (CS) |
+----------------+
| |
+----------------+
|
|-------------------+
| | |
+---------------+ | +---------------+
| ParticipantA | | | ParticipantB |
| | | | |
+---------------+ | +---------------+
| | |
sends | | | sends
| | |
+---------------+ | +---------------+
|Media Stream A1| | |Media Stream B1|
+---------------+ | +---------------+
|MediaStream Ref| | |MediaStream Ref|
|codec params |---+---|codec params |
+---------------+ +---------------+
5.2. Use case 2: Basic Call with hold/resume
Basic call between two Participants A and B and with Participant A or
B doing a Hold/Resume. In this use case each participant sends one
Media Stream. After Hold/Resume the properties of Media MAY change.
+-------------------------------+
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| Recording Session (RS) |
+-------------------------------+
|
|
|
+-------------------------------+
| Communication Session (CS) |
| Group(CSG) |
+-------------------------------+
| Unique-id1 |
+-------------------------------+
|
|
|
+----------------+
| Communication |
+-| Session (CS) |----------------------------------------------+
| +----------------+ |
| | | |
| +----------------+ |
| | |
| |-------------------+ |
| | | |
| +---------------+ +---------------+ |
| | ParticipantA | | ParticipantB |-----------+ |
| | |--+ | | | |
| +---------------+ | +---------------+ |sends(After |
| | | | | | | Resume) |
| | | | | | +--------------+ |
| sends | | +--+ | sends | |MediaStream B3| |
| | -----+ | | +-----+ +--------------+ |
| +---------------+ | | +---------------+ | |MediaStreamRef|-|
| |Media Stream A1| | | |Media Stream B1| | |Codec Params | |
| +---------------+ | | +---------------+ | | | |
+-|MediaStreamref | | | |MediaStreamRef | | +--------------+ |
|codec params | | | |codec params |-|-------------------|
+---------------+ | | +---------------+ | |
| | | |
+------------+ |sends |sends (hold) |
| sends |(Resume) | |
| (hold) +-------+ +-------+ |
| | | |
+---------------+ +---------------+ +--------------+ |
|Media Stream A2| |Media Stream A3| |MediaStream B2| |
+---------------+ +---------------+ | | |
|MediaStreamref | |MediaStreamRef | +--------------+ |
|codec params | |codec params | |Codec Params | |
+---------------+ +---------------+ |MediaStreamRef| |
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| | | | |
| | +--------------+ |
| | | |
+------------------------------------------------------+
NOTE: Need discssions on how to represent Hold/Resume from SRC to SRS
and Pause/Resume from SRS to SRC.
5.3. Use case 3: Basic call with Transfer
Basic call between two Participants A and B and with Participant A
transfer(consult transfer) to Participant C. In this use case each
participant sends one Media Stream. After transfer the properties of
Participant A Media MAY change.
+-------------------------------+
| Recording Session (RS) |
+-------------------------------+
|
|
|
+-------------------------------+
| Communication Session (CS) |
| Group(CSG) |
+-------------------------------+
| Unique-id1 |
+-------------------------------+
|
|-----------------
| |
+----------------+ +----------------+
| Communication | | Communication |
| Session (CS)1 | | Session (CS)2 |
+----------------+ +----------------+-----------+
| | | | |
+----------------+ +----------------+ |
| |
|-------------------+ |
| | | |
+---------------+ | +---------------+ |
| ParticipantA | | | ParticipantB | |
| | | | | |
+---------------+ | +---------------+ |
| | | |
sends | | | sends |
| | | |
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+---------------+ | +---------------+ |
|Media Stream A1| | |Media Stream B1| |
+---------------+ | +---------------+ |
| | | | | |
|codec params | | | Media Stream | |
| Media Stream |---+---| Ref | |
| Ref | |codec params | |
+---------------+ +---------------+ |
|
|
+----------------------------|
| |
+--------------------------------+ |
| | |
+---------------+ +---------------+ |
| Participant A | | Participant C | |
| | | | |
+---------------+ +---------------+ |
| | |
| sends (After transfer) | sends |
+----------------+ +----------------+|
| Media Stream A2| | Media Stream C1||
+----------------+ +----------------+|
| Media StreamRef| | Media StreamRef||
| Codec params | | Codecparams ||
| | | ||
+----------------+ +----------------+|
| | |
| | |
| | |
+-------------------------------------------+
6. Security Considerations
The metadata information sent from SRC to SRS MAY reveal sensitive
Information about different participants of CS. For this reason, it
is RECOMMENDED that a SRC use a strong means for authentication and
metadata information protection and that it apply comprehensive
authorization rules when using the metadata model defined in this
document. The following sections will discuss each of these aspects
in more detail.
6.1. Connection Security
It is RECOMMENDED that a SRC authenticate SRS using the normal SIP
authentication mechanisms, such as Digest as defined in Section 22 of
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[RFC3261]. The mechanism used for conveying the metadata information
MUST ensure integrity and SHOULD ensure confidentially of the
information. In order to achieve these, an end-to-end SIP encryption
mechanism, such as S/MIME described in [RFC3261], SHOULD be used.
If a strong end-to-end security means (such as above) is not
available, it is RECOMMENDED that a SRC use mutual hop-by-hop
Transport Layer Security (TLS) authentication and encryption
mechanisms described in "SIPS URI Scheme" and "Interdomain Requests"
of [RFC3261].
7. IANA Considerations
Not Applicable
8. Acknowledgement
We wish to thank John Elwell, Henry Lum, Leon Portman, De Villers,
Andrew Hutton, Deepanshu Gautam for their valuable comments.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
9.2. Informative References
[I-D.ietf-siprec-req]
Rehor, K., Portman, L., Hutton, A., and R. Jain,
"Requirements for SIP-based Media Recording (SIPREC)",
draft-ietf-siprec-req-06 (work in progress),
December 2010.
[I-D.ietf-siprec-architecture]
Hutton, A., Portman, L., Jain, R., and K. Rehor, "An
Architecture for Media Recording using the Session
Initiation Protocol", draft-ietf-siprec-architecture-01
(work in progress), October 2010.
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Authors' Addresses
Ram Mohan R
Cisco Systems, Inc.
Cessna Business Park,
Kadabeesanahalli Village, Varthur Hobli,
Sarjapur-Marathahalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: rmohanr@cisco.com
Parthasarathi R
Cisco Systems, Inc.
Cessna Business Park,
Kadabeesanahalli Village, Varthur Hobli,
Sarjapur-Marathahalli Outer Ring Road
Bangalore, Karnataka 560103
India
Email: partr@cisco.com
P. Kyzivat
Cisco Systems, Inc.
1414 Massachusetts Avenue
Boxborough, MA 01719
USA
Email: pkyzivat@cisco.com
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