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.
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document authors. All rights reserved.
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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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