Requirements for an End-to-End Session Identification in IP-Based Multimedia Communication Networks
draft-ietf-insipid-session-id-reqts-02

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Document Type Active Internet-Draft (insipid WG)
Authors Paul Jones  , Gonzalo Salgueiro  , James Polk  , Laura Liess  , Hadriel Kaplan 
Last updated 2012-10-09
Replaces draft-jones-insipid-session-id-reqts
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Network Working Group                                      Paul E. Jones
Internet Draft                                         Gonzalo Salgueiro
Intended status: Informational                                James Polk
Expires: April 9, 2013                                     Cisco Systems
                                                             Laura Liess
                                                        Deutsche Telekom
                                                          Hadriel Kaplan
                                                             Acme Packet
                                                         October 9, 2012

         Requirements for an End-to-End Session Identification in
                IP-Based Multimedia Communication Networks
                draft-ietf-insipid-session-id-reqts-02.txt

Abstract

   This document specifies the requirements for an end-to-end session
   identifier in IP-based multimedia communication networks.  This
   identifier would enable endpoints, intermediate devices, and
   management and monitoring systems to identify a session end-to-end
   across multiple SIP devices, hops, and administrative domains.

Status of this Memo

   This Internet-Draft is submitted 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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   This Internet-Draft will expire on April 9, 2013.

Copyright Notice

   Copyright (c) 2012 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
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Table of Contents

   1. Introduction...................................................2
   2. Terminology....................................................3
   3. Session Identifier Use Cases...................................3
      3.1. End-to-end identification of a communication session......3
      3.2. DELETED...................................................4
      3.3. Protocol Interworking.....................................4
      3.4. Traffic Monitoring........................................4
      3.5. DELETED...................................................5
      3.6. Tracking transferred sessions.............................5
      3.7. Session Signal Logging....................................5
      3.8. Identifier Porting to Other Protocols - RTCP..............5
      3.9. 3PCC Use Case.............................................5
   4. Requirements for the End-to-End Session Identifier.............6
   5. Related Work in other Standards Organizations..................7
      5.1. Coordination with the ITU-T...............................7
      5.2. Requirements within 3GPP..................................7
   6. Security Considerations........................................8
   7. IANA Considerations............................................8
   8. Acknowledgments................................................8
   9. References.....................................................8
      9.1. Normative References......................................8
      9.2. Informative References....................................8
   Author's Addresses................................................9

1. Introduction

   IP-based multimedia communication systems like SIP [1] and H.323 [2]
   have the concept of a "call identifier" that is globally unique.  The
   identifier is intended to represents an end-to-end communication
   session from the originating device to the terminating device.  Such
   an identifier is useful for troubleshooting, billing, session
   tracking, and so forth.

   Unfortunately, there are a number of factors that contribute to the
   fact that the current call identifiers defined in SIP and H.323 are
   not suitable for end-to-end session identification.  Perhaps most
   significant is the fact that the syntax for the call identifier in
   SIP and H.323 is different between the two protocols.  This important
   fact makes it impossible for call identifiers to be exchanged end-to-
   end when a network utilizes one or more session protocols.

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   Another reason why the current call identifiers are not suitable to
   identify the session end-to-end is that in real-world deployments
   devices like Back-to-Back User Agents often change the values as the
   session signaling passes through.  This is true even when a single
   session protocol is employed and not a byproduct of protocol
   interworking.

   Lastly, identifiers that might have been used to identify a session
   end-to-end fail to meet that need when sessions are manipulated
   through supplementary service interactions.  For example, when a
   session is transferred or if a PBX joins or merges two communication
   sessions together locally, the end-to-end properties of currently-
   defined identifiers are lost.

2. Terminology

   SIP defines additional terms used in this document that are specific
   to the SIP domain such as "proxy"; "registrar"; "redirect server";
   "user agent server" or "UAS"; "user agent client" or "UAC"; "user
   agent" (UA); "back-to-back user agent" or "B2BUA"; "dialog";
   "transaction"; "server transaction".

   In this document, the word "session" refers to a
   "communication session" that may exist between two SIP user agents or
   that might pass through one or more intermediary devices, including
   B2BUAs or SIP Proxies.

   The term "end-to-end" in this document means the communication
   session from the point of origin, passing through any number of
   intermediaries, to the ultimate point of termination. It is
   recognized that legacy devices may not support the "end-to-end"
   session identifier, though an identifier might be created by an
   intermediary when it is absent from the session signaling.

3. Session Identifier Use Cases

3.1. End-to-end identification of a communication session

   SIP messaging that either does not involve SIP servers or only
   involves SIP proxies, the Call-ID: header value sufficiently
   identifies each SIP message within a transaction or dialog. This is
   not the case when either B2BUAs or SBCs are in the signaling path
   between UAs. Therefore, we need the ability to identify each
   communication session per transaction through a single SIP header-
   value regardless of which type of SIP servers are in the signaling
   path between UAs. For transactions that create a dialog, have each
   message within the same dialog MUST use the same identifier.

   Derived Requirements: All Requirements in Section 4

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3.2. DELETED

3.3. Protocol Interworking

   A communication session might originate in an H.323 endpoint and pass
   through a Session Border Controller before ultimately reaching a
   terminating SIP user agent. Likewise, a call might originate on a SIP
   user agent and terminate on an H.323 endpoint. It MUST be possible to
   identify such sessions end-to-end across the plurality of devices,
   networks, or administrative domains.

   It is expected that the ITU-T will define protocol elements for H.323
   to make the end-to-end signaling possible.

   Derived Requirements: REQ7, REQ9a

3.4. Traffic Monitoring

   UA A and UA B communicate using SIP messaging with a SIP B2BUA acting
   as a middlebox which belongs to a SIP service provider. For privacy
   reasons, the B2BUA changes the SIP headers that reveal information
   related to the SIP users, device or domain identity. The service
   provider uses an external device to monitor and log all SIP traffic
   coming to and from the B2BUA.  In the case of failures reported by
   the customer or when security issue arise (e.g. theft of service),
   the service provider has to analyze the logs from the past several
   days or weeks and correlates those messages which were messages for a
   single end-to-end SIP session.

   For this scenario, we must consider three particular use cases:

     a) The UAs A and B support the end-to-end Session Identifier.

        Derived Requirements: REQ1, REQ4, REQ5, REQ8.

     b) Only the UA A supports the end-to-end Session Identifier, the UA
        B does not.

        Derived Requirements: REQ1, REQ4, REQ5, REQ7, REQ8.

     c) UA A and UA B do not support the end-to-end Session Identifier.

        Derived Requirements: REQ1, REQ4, REQ5, REQ7, REQ8

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3.5. DELETED

3.6. Tracking transferred sessions

   It is difficult to track which SIP messages where involved in the
   same call across transactions, especially when invoking supplementary
   services such as call transfer or call join. The ability to track
   communications sessions as they are transferred, one side at a time,
   through until completion of the session (i.e., until a BYE is sent).

   Derived Requirements: REQ1, REQ2, REQ10

3.7. Session Signal Logging

   An after the fact search of SIP messages to determine which were part
   of the same transaction or call is difficult when B2BUAs and SBCs are
   involved in the signaling between UAs. Mapping more than one Call-ID
   together can be challenging because all of the values in SIP headers
   on one side of the B2BUA or SBC will likely be different than those
   on the other side. If multiple B2BUAs and/or SBCs are in the
   signaling path, more than two sets of header values will exist,
   creating more of a challenge. Creating a common header value through
   all SIP entities will greatly reduce any challenge for the purposes
   of debugging, communication tracking (such as for security purposes
   in case of theft of service), etc.

   Derived Requirements: REQ1, REQ4, REQ7, REQ8

3.8. Identifier Porting to Other Protocols - RTCP

   There may be a desire to associate SIP session signaling with
   corresponding media flows.  To facilitate this association, it should
   be possible to insert the Session-ID into a media-related message,
   such as an RTCP sender report message.  This association would allow,
   as an example, for network monitoring equipment to associate troubled
   network flows with the end-to-end SIP session signaling.

   Derived Requirements: REQ9c

3.9. 3PCC Use Case

   Third party call control refers to the ability of an entity to create
   a call in which communication is actually between two or more
   parties. For example, a B2BUA acting as a third party controller
   could establish a call between two SIP UA's using 3PCC procedures as
   described in section 4.1 of RFC 3725 the flow for which is reproduced
   below.

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                 A              Controller               B
                 |(1) INVITE no SDP  |                   |
                 |<------------------|                   |
                 |(2) 200 offer1     |                   |
                 |------------------>|                   |
                 |                   |(3) INVITE offer1  |
                 |                   |------------------>|
                 |                   |(4) 200 OK answer1 |
                 |                   |<------------------|
                 |                   |(5) ACK            |
                 |                   |------------------>|
                 |(6) ACK answer1    |                   |
                 |<------------------|                   |
                 |(7) RTP            |                   |
                 |.......................................|

                     Figure 1 - Session-ID 3PCC Scenario

   Such a flow must result in a single session identifier being used for
   the communication session between UA A and UA B. This use case does
   not extend to three SIP UAs.

   Derived Requirements: REQ10

4. Requirements for the End-to-End Session Identifier

   The following requirements are derived from the use cases and
   additional constraints regarding the construction of the identifier.

   REQ1: It must be possible for an administrator or an external device
   which monitors the SIP-traffic to use the identifier to identify
   those dialogs, transactions and messages which were at some point in
   time components of a single end-to-end SIP session (e.g., parts of
   the same call).

   REQ2: It must be possible to correlate two end-to-end sessions when a
   session is transferred or if two different sessions are joined
   together via an intermediary (e.g., a PBX).  This might result in a
   change in the value of the end-to-end Session-Identifier.

   REQ4: It must be possible to pass the identifier unchanged through
   SIP B2BUAs or other intermediaries.

   REQ5: The identifier must not reveal any information related to any
   SIP user, device or domain identity.  This includes any IP Address,
   port, hostname, domain name, username, Address-of-Record, MAC
   address, IP address family, transport type, subscriber ID, Call-ID,
   tags, or other SIP header or body parts.

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   REQ7: It must be possible to identity SIP traffic with an end-to-end
   session identifier from and to end devices that do not support this
   new identifier, such as by allowing an intermediary to inject an
   identifier into the session signaling.

   REQ8: The identifier should be unique in time and space, similar to
   the Call-ID.

   REQ9a: The identifier should be constructed in such a way as to make
   it suitable for transmission in SIP and H.323.

   REQ9c: The identifier should be constructed in such a way as to make
   it suitable for transmission in SIP and RTCP [3].

   REQ10: It must be possible to correlate two end-to-end sessions when
   the sessions are created by a third party controller using 3PCC
   procedures shown in Figure 1 of RFC 3725 [6].

5. Related Work in other Standards Organizations

5.1. Coordination with the ITU-T

   IP multimedia networks are often comprised of a mix of session
   protocols like SIP and H.323. A benefit of the Session Identifier is
   that it uniquely identifies a communication session end-to-end across
   session protocol boundaries. Therefore, the need for coordinated
   standardization activities across Standards Development Organizations
   (SDOs) is imperative.

   To facilitate this, a parallel effort is underway in the ITU-T to
   introduce the Session Identifier for the H.323 protocol. The ITU-T
   SG16 has approved contribution C.552 [4] as a work item with the
   intent that it be a coordinated and synchronized effort between the
   ITU-T and the IETF.

5.2. Requirements within 3GPP

   3GPP identified in their Release 9 the need for a Session Identifier
   for O&M purposes to correlate flows in an end-to-end communication
   session.  TS24.229 (IP multimedia call control protocol based on
   Session Initiation Protocol (SIP) and Session Description Protocol
   (SDP)) [5] points to the fact that the Session Identifier can be used
   to correlate SIP messages belonging to the same session.  In the case
   where signaling passes through SIP entities like B2BUAs, the end-to-
   end session identifier indicates that these dialogs belong to the
   same end-to-end SIP communication session.

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6. Security Considerations

   An end-to-end identifier, if not properly constructed, could provide
   information that would allow one to identify the individual, device,
   or domain initiating or terminating a communication session.  In
   adherence with REQ5, the solution produced in accordance with these
   requirements MUST NOT provide any information that allow one to
   identify a person, device, or domain.  This means that information
   elements such as the MAC address or IP address MUST NOT be used when
   constructing the end-to-end session identifier.

7. IANA Considerations

   There are no IANA considerations associated with this document.

8. Acknowledgments

   The authors would like to acknowledge Chris Pearce for his
   contribution and collaboration in developing this document.

   This document was prepared using 2-Word-v2.0.template.dot.

9. References

9.1. Normative References

   [1]   Rosenberg, J., et al., "SIP: Session Initiation Protocol", RFC
         3261, June 2002.

   [2]   Recommendation ITU-T H.323, "Packet-based multimedia
         communications systems", December 2009.

9.2. Informative References

   [3]   Schulzrinne, H., et al., "RTP: A Transport Protocol for Real-
         Time Applications", RFC 3550, July 2003.

   [4]   International Telecommunications Union, "End-to-End Session
         Identifier for IP-based Multimedia Communication Systems",
         March 2011, ITU-T Contribution C.552, http://ftp3.itu.int/av-
         arch/avc-site/2009-2012/1103_Gen/SessionID.zip.

   [5]   3GPP, "IP multimedia call control protocol based on Session
         Initiation Protocol (SIP) and Session Description Protocol
         (SDP); Stage 3", 3GPP TS 24.229 10.3.0, April 2011.

   [6]   Rosenberg, J., Peterson, J., Schulzrinne, H., Camarillo, G.,
         "Best Current Practices for Third Party Call Control (3pcc) in
         the Session Initiation Protocol (SIP)", RFC 3725, April 2004.

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Author's Addresses

   Roland Jesske
   Deutsche Telekom NP
   64295 Darmstadt
   Heinrich-Hertz-Str. 3-7
   Germany

   Phone: +49 6151 628 2766
   Email: R.Jesske@telekom.de

   Paul E. Jones
   Cisco Systems, Inc.
   7025 Kit Creek Rd.
   Research Triangle Park, NC 27709
   USA

   Phone: +1 919 476 2048
   Email: paulej@packetizer.com
   IM: xmpp:paulej@packetizer.com

   Hadriel Kaplan
   Acme Packet
   71 Third Ave.
   Burlington, MA 01803, USA

   Email: hkaplan@acmepacket.com

   Laura Liess
   Deutsche Telekom NP
   64295 Darmstadt
   Heinrich-Hertz-Str. 3-7
   Germany

   Phone: +49 6151 268 2761
   Email: laura.liess.dt@gmail.com

   Salvatore Loreto
   Ericsson
   Hirsalantie 11
   Jorvas 02420
   Finland

   Email: salvatore.loreto@ericsson.com

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   James Polk
   Cisco Systems, Inc.
   3913 Treemont Circle
   Colleyville, Texas,
   USA

   Phone: +1 817 271 3552
   Email: jmpolk@cisco.com
   IM: xmpp:jmpolk@cisco.com

   Parthasarathi Ravindran
   Sonus Networks, Inc.
   Prestige Shantiniketan - Business Precinct
   Whitefield Road
   Bangalore, Karnataka 560066
   India

   Email: pravindran@sonusnet.com

   Gonzalo Salgueiro
   Cisco Systems, Inc.
   7025 Kit Creek Rd.
   Research Triangle Park, NC 27709
   USA

   Phone: +1 919 392 3266
   Email: gsalguei@cisco.com
   IM: xmpp:gsalguei@cisco.com

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