SPEERMINT WG                                                    A. Houri
Internet-Draft                                                       IBM
Intended status: Informational                                   E. Aoki
Expires: August 18, 2008                                         AOL LLC
                                                           S. Parameswar
                                                  Microsoft  Corporation
                                                       February 15, 2008

             Presence & Instant Messaging Peering Use Cases

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Copyright Notice

   Copyright (C) The IETF Trust (2008).


   The document describes several use cases of peering of non-VoIP
   services between two or more Service Providers.  These Service
   Providers create a peering relationship between themselves thus
   enabling their users to collaborate with users on the other Service
   Provider network.  The target of the document is to drive

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   requirements for peering between domains that provide the non-VoIP
   based collaboration services and presence and Instant Messaging (IM)
   in particular.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.1.  Simple Interdomain Subscription . . . . . . . . . . . . . . 3
     2.2.  List Based Interdomain Subscription . . . . . . . . . . . . 3
     2.3.  Authorization Migration . . . . . . . . . . . . . . . . . . 4
     2.4.  Page Mode IM  . . . . . . . . . . . . . . . . . . . . . . . 5
     2.5.  Session Based IM  . . . . . . . . . . . . . . . . . . . . . 5
     2.6.  Other Services  . . . . . . . . . . . . . . . . . . . . . . 5
     2.7.  Federation & Clearing House . . . . . . . . . . . . . . . . 5
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   5.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 7
   6.  Informative References  . . . . . . . . . . . . . . . . . . . . 7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 8
   Intellectual Property and Copyright Statements  . . . . . . . . . . 9

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1.  Introduction

   The document uses the terminology as defined in [1] unless otherwise

   Real Time Collaboration (RTC) services become as prevalent and
   essential for users on the Internet as email.  While RTC services can
   be implemented directly by users in a point-to-point fashion, they
   are often provided for or on behalf of a Peer Network of users within
   an administrative domain.  As the use of these services grows, users
   increasingly have the need to communicate with users not only within
   their own Peer Network but with those in other Peer Networks as well
   (similar to the old Public Switched Telephony Network (PSTN) that
   enabled global readability).  In practice, each Peer Network is
   controlled by some domain, and so there is a need to provide for
   easier establishment of connectivity between Peer Networks, and the
   management of the relationships between the Peer Networks.  This
   document describes a set of use cases that describe how peering
   between Peer Networks may be used in non Voice over IP (VoIP) RTC
   services.  The use cases are intended to help in identifying and
   capturing requirements that will guide and then enable a secure and
   easier peering between Peer Networks that provide non-VoIP RTC
   services.  The use cases for the VoIP RTC services are described in

2.  Use Cases

2.1.  Simple Interdomain Subscription

   Assume two Peer Networks, Peer Network A and Peer Network B. User
   Alice@example.com (hosted in Peer Network A), wants to subscribe to
   user Bob@example.net (hosted in Peer Network B) and get his presence
   information.  In order to do so, Alice@example.com could connect
   directly to example.net and subscribe to Bob's presence information.
   However, Peer Network B is willing to accept subscriptions and route
   IMs only when they are coming from its users or from other Peer
   Networks that Peer Network B trusts.

   In reality what will happen is that Peer Network A will connect to
   peer network B and will send Alice's subscription to Bob via Peer
   Network B. When peer network B has new information on Bob it will
   send notifications to Peer Network A that will pass them to Alice.

2.2.  List Based Interdomain Subscription

   This is similar to the simple interdomain subscription use case
   except that in this case Alice subscribes to a Uniform Resource

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   Identifier (URI) [8] that represents a list of users in Peer Network
   B [9] [3]

   There are several types of lists that Alice may subscribe to:

   o  Personal group - A list that was created and maintained by Alice
      and includes Alice's watch list.
   o  Public group - A list that is created and maintained by an
      administrator and is typically referred to as a public group.
      Public groups usually contains a list of specific people that have
      some common characteristic e.g. support group of a company.
   o  Ad-hoc group - A list that is short lived and is usually created
      in a context of some activity that Alice is doing.  An ad-hoc
      group may be created by Alice or by some application.  Typical
      examples may be the list of people that participate with Alice in
      a conference or a game.

2.3.  Authorization Migration

   If many users from one Peer Network watch presentities [6] in another
   Peer Network, it may be possible that many watchers [6] from one Peer
   Network will subscribe to the same user in the other Peer Network.
   However, due to privacy constraints that enable a user to provide
   different presence documents to different watchers, each Peer Network
   will have to send multiple copies of the watched presence document.
   The need to send multiple copies between the Peer Networks is very
   inefficient and causes redundant traffic between the Peer Networks.

   In order to make the subscription between Peer Networks more
   efficient there needs to be a way to enable Peer Networks to agree to
   share privacy information between them.  This will enable sending a
   single copy (the full copy) of the presence document of the watched
   user and letting the receiving Peer Network to be responsible for
   sending the right values to the right watchers according to the
   delegated privacy policies of the watched users.

   Instead of sharing watcher's privacy policies between the Peer
   Networks, it is also possible to send different copies of the
   presence document with a list of the watchers that the presence
   document is intended for.  For example, if there is a set of watchers
   in the other Peer Network that may see the location of the presentity
   and another set of users in the other Peer Network that may not see
   the location information, two presence documents will be sent, each
   one is associated with a list of watchers that should receive it.
   One presence document will contain the location information and will
   be associated with a list of users that may see it and the other
   presence document will not contain the location information and will
   be associated with a list of users that may not see the location

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2.4.  Page Mode IM

   In this use case a user from one Peer Network sends a page mode [7]
   IM to a user on another Peer Network.

2.5.  Session Based IM

   In this use case a user from one Peer Network creates a Message
   Session Relay Protocol (MSRP) [10] session with a user from another
   Peer Network.

2.6.  Other Services

   In addition to VoIP sessions which are out of scope for this document
   only presence and IM have been ratified as RFCs.  In addition to
   presence and IM, there are many other services that are being
   standardized or may be implemented using minimal extensions to
   existing standards.  These include:

   o  N-way chat - Enable a multi-participant textual chat that will
      include users from multiple Peer Networks.  See [4] for more
   o  File transfer - Send files from a user in one Peer Network to a
      user in another Peer Network.  See [5] for more details.
   o  Document sharing - Sharing and editing a document between users in
      different Peer Networks.

      Note: Document sharing is mentioned in this document only for
      completeness of use cases.  It is not being standardized by the
      IETF and will not be included the requirements draft that will
      result from this document.

   The list above is of course not exhaustive as new developments in the
   world of non-VOIP RTC will surface new services.  Enabling peering
   between networks for some of the services will create a basis for
   enabling peering also for future services.

2.7.  Federation & Clearing House

   A Federation as defined in [1] enables peering between multiple Peer
   Networks.  A federation may be implemented by means of a central
   service providing a hub for the Peer Networks or, alternatively, Peer
   Networks may connect to each other in a peer-to-peer fashion.  One of
   the most important services that this type of federation should
   provide is authorized interconnection that enables each Peering
   Network to securely identify other Peering Networks.  Other services

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   that might be provided include an N-way chat server, lawful
   interception, logging and more.  This type of federation is also
   known as a "Clearing House".

   As non-VoIP services are usually text-based and consume less
   bandwidth, they may benefit from having a central service that will
   do central services such as logging for them.  For example, instead
   of requiring each Peer Network to log all messages that are being
   sent to the other Peer-Network, this service can be done by the
   Clearing House.

3.  IANA Considerations

   This document has no actions for IANA.

4.  Security Considerations

   When Peer Network A peers with Peer Network B, there are several
   security issues that the administrator of each Peer Network will need
   mechanisms to verify:

   o  All communication channels between Peer Network and between each
      Peer Network and the clearing house have their authenticity and
      confidentiality protected.
   o  The other Peer Network is really the Peering Network that it
      claims to be.
   o  The other Peer Network is secure and trustful such that
      information that is passed to it, will not reach a third party.
      This includes information about specific users as well as
      information about the authorization policies associated with user
   o  The other Peer Network is secure and trustful such that it will
      not modify or falsify data that it presents to its users except as
      required by the authorization policy provided.
   o  If there is a third party (e.g. a clearing house) involved in the
      connection between the two Peering Networks that element is also
      verified to be secure.

   The same issues of security are even more important from the point of
   view of the users of the Peer Networks.  Users will have the concern
   on how their privacy is being adhered to when their presence
   information is being sent to the other Peer Network.  Users today are
   concerned about providing their email address to a third party when
   they register to a domain; Presence contains much more sensitive
   information and the concern of users here will be even deeper.

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   The privacy issue is even harder if we take into account that in
   order to enable scalable peering between big Peer Networks there are
   some optimizations that may require migration of the privacy
   definitions of users between Peer Network (see Section 2.3).  We can
   imagine the fiasco if a user of one Peer Network will be able to see
   the privacy information and will learn he/she are listed in a block
   list of a close friend.

   This document discusses use cases for peering between Peer Networks.
   It is out of scope for the document to provide solutions for
   security.  Nevertheless, it is obvious that the protocols that will
   enable the use cases that are described here will have to provide for
   the security considerations described here.

5.  Acknowledgments

   We would like to thank Jonathan Rosenberg, Jon Peterson, Rohan Mahy,
   Jason Livingood, Alexander Mayrhofer, Joseph Salowey, Henry Sinnreich
   and Mohamed Boucadir for their valuable input.

6.  Informative References

   [1]   Malas, D. and D. Meyer, "SPEERMINT Terminology",
         draft-ietf-speermint-terminology-16 (work in progress),
         February 2008.

   [2]   Uzelac, A., "VoIP SIP Peering Use Cases",
         draft-ietf-speermint-voip-consolidated-usecases-05 (work in
         progress), February 2008.

   [3]   Camarillo, G. and A. Roach, "Framework and Security
         Considerations for Session Initiation Protocol (SIP)  Uniform
         Resource Identifier (URI)-List Services",
         draft-ietf-sipping-uri-services-07 (work in progress),
         November 2007.

   [4]   Niemi, A., Garcia-Martin, M., and G. Sandbakken, "Multi-party
         Instant Message (IM) Sessions Using the Message Session Relay
         Protocol (MSRP)", draft-ietf-simple-chat-02 (work in progress),
         February 2008.

   [5]   Garcia-Martin, M., Isomaki, M., Camarillo, G., Loreto, S., and
         P. Kyzivat, "A Session Description Protocol (SDP) Offer/Answer
         Mechanism to Enable File  Transfer",
         draft-ietf-mmusic-file-transfer-mech-06 (work in progress),
         December 2007.

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   [6]   Day, M., Rosenberg, J., and H. Sugano, "A Model for Presence
         and Instant Messaging", RFC 2778, February 2000.

   [7]   Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C., and
         D. Gurle, "Session Initiation Protocol (SIP) Extension for
         Instant Messaging", RFC 3428, December 2002.

   [8]   Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
         Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
         January 2005.

   [9]   Roach, A., Campbell, B., and J. Rosenberg, "A Session
         Initiation Protocol (SIP) Event Notification Extension for
         Resource Lists", RFC 4662, August 2006.

   [10]  Campbell, B., Mahy, R., and C. Jennings, "The Message Session
         Relay Protocol (MSRP)", RFC 4975, September 2007.

Authors' Addresses

   Avshalom Houri
   Science Park Building 18/D

   Email: avshalom@il.ibm.com

   Edwin Aoki
   360 W.  Caribbean Drive
   Sunnyvale, CA  94089

   Email: aoki@aol.net

   Sriram Parameswar
   Microsoft  Corporation
   One Microsoft  Way
   Redmond, WA  98052

   Email: Sriram.Parameswar@microsoft.com

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