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Formalising the Next Generation “Signalling Network_

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					       Formalising the Next Generation “Signalling Network”
                                       Babatunde Orimoloye and Hu Hanrahan
                               Centre for Telecommunications and Access and Services1
                                  School of Electrical and Information Engineering
                                    University of the Witwatersrand, Johannesburg
                                Telephone: (+2711-7177243), Fax :( +2711-4031929)
                                  E-mail: {b.orimoloye, h.hanrahan}@ee.wits.ac.za
                                                                 support real-time services and multimedia applications.
   Abstract—With           the       convergence     of             (4) To design and dimension the signalling transport layer
telecommunication and information services and                   for traffic engineering.
infrastructures to the realization of Next Generation               Section II reviews the signalling and transport networks
Network (NGN), there is need for this emerging network           relevant to this work. Section III outlines the steps required
to accommodate existing multimedia technologies and              in the research.
applications and paving way for easy deployment of
future services. Highly available and dependable                         II. SIGNALLING TRANSPORT TECHNOLOGIES
signalling is a key requirement for the NGN. This paper
reports on work in progress to define the Next                     A. IP/MPLS Network Technology
Generation signalling network architecture. The                     The Internet is an IP-based multiservice network
signalling system must accommodate different                     consisting of autonomous systems using best effort
multimedia applications which span over heterogeneous            algorithm in the transmission of data packets between
networks.                                                        network element nodes. The Internet, partly due to its
                                                                 ubiquitous nature and flexible multiservice platform
  Index Terms—Next Generation Network, Network
                                                                 characteristics, is often proposed as a promising candidate
Performance, Quality of Service, Signalling Transport
                                                                 for the Next Generation transport network. However, the IP
                                                                 packet transport network has little inherent structure, lacks
                   I. INTRODUCTION                               QoS guarantees and is inherently unreliable. In the NGN,
                                                                 measures are taken to structure this packet mode network
   The Next Generation Network is a multiservice packet          for performance [5]. The NGN-IP paradigm structures the
mode transport network capable of interworking with legacy       Multiprotocol Label Switching (MPLS) enabled core
networks. As the transport is a packet based network,            network for QoS using DiffServ and policy-based admission
control and management messages do not require a separate        applications.
network as in the case of circuit switched networks where
common channel signalling is transported by the separate           B. SS7 Network Architecture
Signalling System No. 7 (SS7) network. A further attempt            In the Classical PSTN/IN implementation, the Intelligent
to elaborate on the visions of the NGN is discussed in [1].      Network (IN) architecture is an overlay network on the
Amongst other features of the NGN is the ability of packet       traditional circuit switched PSTN. This signalling network
switched data networks to interwork with voice circuit           architecture is supported by the ITU-T Signalling System
switched network via signalling, trunking and media              No 7 (SS7) network. The highly reliable and dependable
gateways.                                                        SS7 network is made up of nodes and links to support
   In this work in progress paper, we seek to explore the        signalling messages for call and connection control in
various Next Generation Network initiatives leading to a         switched circuit networks.
signalling network architecture concept for supporting              While there is no overlay signalling network in the NGN,
multimedia applications across heterogeneous networks.           SS7 is relevant because new network must interwork with
   The objective of this work is: -                              legacy networks, SS7 application layer messages must be
   (1) To build a typical model for the signaling transport      transported to nodes in the NGN, and signalling transport in
layer capable of supporting multimedia application across        the NGN must have similar performance to SS7.
distributed computing nodes in a packet mode network.
                                                                   C. The SIGTRAN Architecture
   (2) To map typical upper layer implementation such as            The SIGTRAN protocol suite – an initiative of the
the application and service layer onto the NGN [2].              Internet Engineering Task Force (IETF) Signalling
   (3) To structure the core packet based transport network      Transport (SIGTRAN) working group – is a development to
for performance, reliability and high availability in order to   structure the Internet IP-based multiservice network. A
                                                                 description of this generic architecture is detail in [3]. The
  The Centre is supported by Telkom SA Limited, Siemens          SIGTRAN protocol suite is shown in figure 1 with the
Telecommunications, Sun Microsystems SA and the THRIP            network layer IP protocol supporting upper layer protocols.
Programme of the Department of Trade and Industry                The stream control transmission protocol (SCTP) is defined
in [4]. SCTP is a connection-oriented protocol that is                               REFERENCES
designed to be a reliable transport protocol for signalling    [1] H.E. Hanrahan and D. Mwansa A vision for the target
messages supporting real-time, message oriented                    next generation network. In Proceedings of SATNAC
multimedia applications. An SCTP connection is called an           2003, 2003.
association. An association is identified by the two SCTP      [2] H.E.     Hanrahan.     A     comparative    study   of
endpoints. Amongst the features of SCTP is multi-homing            telecommunications architectures: Methodology and
and multi-streaming, these features provides high                  case studies. In Submitted to SATNAC2003, 2003.
availability and reliability respectively to support the       [3] L. Ong, et al., Framework Architecture for Signalling
signalling performance requirements of SS7 networks in             Transport, RFC 2719, October 1999.
circuit switched networks.                                     [4] R.Stewart, et al., Stream Control Transport Protocol,
                                                                   RFC 2960, October 2000.
                                                               [5] H. Morar, S. Mohapi, and H.E Hanrahan. Using the
                    TCAP                                           TINA Network Resource Architecture to provide QoS
                                                                   guaranteed connectivity in MPLS networks. In
                                                                   Proceedings of SATNAC 2001, 2001.
               SCCP
                                                               [6] H.E. Hanrahan TINA, SATINA and the next generation
                                               ISDN                network: Results, status and prospects. In Proceedings
                    MTP3                                           of SATNAC 2003, 2003.
                                                               [7] Principles of TINA www.tinac.com
     M3U       M2PA        M2UA      SUA       IUA
      A


                          SCTP

                            IP


  Fig 1. : SIGTRAN protocol suite

  The SIGTRAN adaptation layer consists of various
adaptation modules to support upper layer protocols.

                      III. APPROACH
   The design will be implemented on a generic Next
Generation Network platform. The approach to this work
will be based on the following steps. First, we identify the
features and requirements of the NGN. Second, we review
current and emerging standards, protocols and network
technologies towards the realization of the Next Generation
signalling transport. Third, we detail an analysis of a
convergence scenario based on a distributed processing
environment using Object Request Broker (ORB) concepts.
Lastly, we define this Next Generation Network by
constructing a generic signalling network.

                      IV. CONCLUSION
   This paper describes ongoing work which aims to define
the possible architecture for Next Generation Signalling
Network. We review current and emerging standards and
technologies focusing on the transport of control and
management messages in a packet mode multiservice
network. The formalization considers various initiatives and
standards that focuses on various NGN features and
recognises various signalling requirements across
heterogeneous networks, such as across different
administrative and technology domains [6]. The problem is
essentially to define a logical network within the NGN
transport network that transports signalling messages as
dependably as Signalling System No 7.

				
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Description: SIGTRAN (Signaling Transport) protocol is the IETF SIGTRAN signaling transmitted by the Working Group established a set of IP networks to send transmission control protocol PSTN signaling. SIGTRAN defines a relatively perfect SIGTRAN protocol stack is divided into IP protocol, signaling transmission, signaling transmission adapter and signaling applications such as four. Each contains as follows: � IP protocol layer: IP � Signaling Transport Layer: SCTP � signaling transport adaptation layer: SUA; M3UA; M2UA/M2PA; IUA � signaling application layer: TCAP; TUP; ISUP; SCCP ; MTP3; Q931/QSIG