DIME Working Group                                            M. Liebsch
Internet-Draft                                                       NEC
Intended status: Standards Track                            July 4, 2011
Expires: January 5, 2012


                        Diameter Bulk Signaling
               draft-liebsch-dime-diameter-bulksig-00.txt

Abstract

   Diameter has received wide acceptance in large scale networking based
   on applications like Network Access Server and Credit Control.
   Different Standards Development Organizations consider Diameter as
   base protocol for extended applications, e.g. to push or pull
   information between a Diameter client and server without alignment of
   application states and identification schemes with the Session-ID
   concept as utilized by the Diameter protocol.  The use of Diameter
   bulk signaling to enable transmission of multi-user context with a
   single or few messages for application state recovery after failure
   represents a further use case, which requires investigation on its
   impact to the Diameter base specification.  This document analyzes
   various use cases for Diameter bulk signaling and assesses practices
   to enable operation of such use cases from extended or new
   applications.

Status of this Memo

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   This Internet-Draft will expire on January 5, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions and Terminology  . . . . . . . . . . . . . . . . .  5
   3.  Overview of Scope and Content  . . . . . . . . . . . . . . . .  6
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 11





























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1.  Introduction

   Diameter [RFC3588] has received wide acceptance in large scale
   networking, e.g. in the 3rd Generation Partnership Project's (3GPP)
   Evolved Packet Core (EPC) network architecture [3GPP-EPC], based on
   applications like Network Access Server [RFC4005] and Credit-Control
   [RFC4006].  Such deployments also depend on application level
   defined, interoperable resilience schemes.  It has been noticed that
   these could potentially be extended beyond the original Diameter
   session model by the concept of bulk handling.  In this manner the
   efficiency of signaling can be enhanced significantly, as multi-user
   context is being conveyed with the exchange of a single or few
   Diameter messages.  Further deployment considers operation of
   stateless applications on top of Diameter to push or pull information
   between a client and a server, disregarding the stateful operation of
   the Diameter protocol.

   3GPP studies approaches for bulk signaling, such as for bulk
   activation/de-activation and bulk registration update.  A
   standardization group of the European Telecommunications Standards
   Institute (ETSI), which is named TISPAN (Telecoms and Internet
   Converged Services and Protocols for Advanced Network), relies on an
   application on top of Diameter to enforce policies via standardized
   network reference points under the control of a Resource and
   Admission Control Subsystem (RACS).  The Diameter Session-ID is
   terminated in Diameter end-points (Server and Client) and is
   transparent to the policy control application [ETSI-183060].

   The problem space for bulk signaling in Diameter can be separated
   into two components: Treatment of a particular user's Session-ID in
   Diameter messages, which carry a Session-ID AVP, and techniques to
   group multi-user context for bulk transmission with a single Diameter
   message.

   Bulk signaling on top of stateless Diameter operation and messages,
   which do not carry a Session-ID, is feasible without breaking the
   Diameter Session concept.  However, the use of Diameter messages
   which rely on the existence of a Diameter Session-ID Attribute Value
   Pair (AVP) as the meaning of the message is in the context of a
   particular user subscription, requires additional rules how to treat
   and interpret the Session-ID of such messages.  The same applies to
   stateless applications, which operate on top of Diameter and use
   messages that comprise a Session-ID AVP.

   This document analyzes various use cases where the Diameter protocol
   can provide a vehicle for stateless operation or for the signaling of
   bulk information.  Practices for stateless operation and bulk
   signaling using Diameter are described, analyzed and assessed



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   according to the level they follow or break the Diameter base
   specification.  Furthermore, approaches to group and identify multi-
   user context for bulk signaling in a single Diameter PDU are
   specified.















































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2.  Conventions and 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 uses the terminology of [RFC3588].












































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3.  Overview of Scope and Content

   This initial version of the draft introduces the problem space when
   using Diameter for bulk signaling and operating stateless
   applications on top of Diameter.  Furthermore, a first collection of
   items, which should be discussed and described in detail in future
   versions of this document, is summarized.  Some items have been
   identified during preceding discussion with the DIME Working Group.

   The following structure and content are proposed for a first revision
   of this document.

   o  Analysis of Use Cases -- This section describes various use cases,
      where the Diameter protocol is already used or considered as
      vehicle for bulk signaling or stateless applications.  Of
      relevance appears the 3GPP's technical evaluation of bulk
      signaling for the recovery of application states after full or
      partial node failure [3GPP-PCRFFR].  Of similar relevance are 3GPP
      use cases for stateless push and pull of user context on the 3GPP
      reference point S6a [3GPP-DIAM].  Furthermore, the ETSI's TISPAN
      group specifies an application for policy enforcement under
      control of a RACS, whereas the identification of user
      subscriptions on application level are not linked to the user-
      specific Session-IDs as per Diameter protocol [ETSI-183060].
      Further existing or new use cases can be described and analyzed.

   o  Practices for Bulk Signaling -- This section describes current
      practices and proposals for new mechanisms to enable Diameter bulk
      signaling as well as the operation of applications on top of
      Diameter, which require no or utilize unrelated identification of
      users.  Current practices as per 3GPP and TISPAN are described.
      New proposals can be included for later assessment.  Current
      practices include overloading as well as disregarding of Diameter
      Session-IDs.

   o  Classification of Practices -- This section assesses the described
      practices and classifies them according to their deviation from
      the Diameter standard as per [RFC3588], their impact on
      implementation complexity, and further aspects.  Recommendations
      may be derived to support current and future standards development
      organizations' activity in this context.  Also, the IETF may
      identify suitable techniques or space for extensions to Diameter
      or its applications to enable target use cases for bulk signaling
      efficiently.

   o  Coding Options to Group Multi-User Context for bulk signaling --
      The efficiency and the benefit when signaling multi-user context
      in a single or a few messages depends on how much and which data



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      can be shared between individual user sessions.  A requirement for
      bulk signaling is that a receiver of bulk signaling can
      unambiguously resolve and assign attributes and values to the
      associated user.  This section describes different options to
      group the context information of multiple users for being
      transmitted in a single message.













































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4.  Security Considerations

   To be done.
















































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5.  IANA Considerations

   So far, no requirement for IANA actions has been identified.
















































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6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3588]  Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
              Arkko, "Diameter Base Protocol", RFC 3588, September 2003.

6.2.  Informative References

   [3GPP-DIAM]
              "3GPP TS 29.272  Mobility Management Entity (MME) and
              Serving  GPRS Support Node (SGSN) related interfaces based
              on Diameter protocol", <http://www.3gpp.org>.

   [3GPP-EPC]
              "3GPP TS 23.401, General Packet Radio Service (GPRS)
              enhancements for Evolved Universal Terrestrial Radio
              Access Network (E-UTRAN) access", <http://www.3gpp.org>.

   [3GPP-PCRFFR]
              "3GPP TS 29.816  3GPP TS 29.272 Study on PRCF Failure and
              Restoration", <http://www.3gpp.org>.

   [ETSI-183060]
              "ETSI TS 183 060, Resources and Admission Control
              Subsystem (RACS); Re interface based on the Diameter
              protocol", <http://www.etsi.org/deliver/etsi_ts/
              183000_183_099/183060/>.

   [RFC4005]  Calhoun, P., Zorn, G., Spence, D., and D. Mitton,
              "Diameter Network Access Server Application", RFC 4005,
              August 2005.

   [RFC4006]  Hakala, H., Mattila, L., Koskinen, J-P., Stura, M., and J.
              Loughney, "Diameter Credit-Control Application", RFC 4006,
              August 2005.












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Author's Address

   Marco Liebsch
   NEC Laboratories Europe
   NEC Europe Ltd.
   Kurfuersten-Anlage 36
   D-69115 Heidelberg,
   Germany

   Phone: +49 6221 4342146
   Email: liebsch@neclab.eu








































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