Advanced Telecommunication NetworksA Framework for Examining Next Generation Networks

CONTENT1 Characteristics of Evolving Networks 1.1 Proliferation of Terminals and Access Networks 1.2 Core Network Types 1.3 Evolution of Service Architectures2 Dealing with Complexity3 Framework for Evolving Networks 3.1 Layering 3.2 Domains 3.3 Planes 3.4 Summary of the NGN Framework4 Examples of Application of Framework 4.1 Legacy Networks Elements in the Framework . 4.2 From Circuit Switch to Soft-switch 4.3 Conceptualizing Convergence in Layered Model . 4.4 Digital Video Broadcasting in the Framework

Characteristics of Evolving NetworksConvergence allows an increased number of services to be supported by common facilities.

However, the total set of facilities is not common and, paradoxically, there is a proliferation of facilities.

Characteristics of Evolving NetworksProliferation of networks, access methods, telecommunications services, terminals and IT/Internet services

Proliferation of Terminals and Access Networks Traditional fixed line phone and fax as well as the ISDN phone and videoconference terminal. 2G mobile phones, originally supporting circuit-switched voice and data, 2.5G packet-mode GPRS data, personal digital assistants 3G mobile phones offer enhanced data services such as videophone and high-speed Internet access. Devices connected to a cable modem or the set-top unit in Digital Video Broadcast have both broadcast reception and interactive capability.Characteristics of Evolving Networks

Proliferation of Terminals and Access Networks3G mobile phone has a standard 3G air interface and is also fitted with WiFi (Ethernet wireless LAN) and Bluetooth.

3G interface, the access network and the core networktogether support real time services (voice and video), messaging (SMS and MMS) and Internet services (e-mail,Web browsing, transactional services and file transfer) limited only by the screen and keypad of the phone.

Multifunction terminal represents the convergence of several services to the user and a unified, standards-based approach tofacilities provision to the telco, that is technology convergence.Characteristics of Evolving Networks

Proliferation of Terminals and Access Networks4G network envisages multiple, heterogeneous access networks but with mechanisms for seamless access to an IP core network. In the access area, convergence is likely to take the form of interworking mechanisms to give seamless roaming rather than merging of actual access networks. Terminals may in fact become more complex, for example with multiple radio frequency front ends: mobile network, wireless LAN and Bluetooth.Seamlessness from the user point of view is embodied in session control and mobility management as well as compatible quality of service for different access mechanisms.Characteristics of Evolving Networks

Core Network Types Circuit-switched networks Internet Protocol, both versions 4 and 6 networks- unmanaged (offers no performance guarantees) and managed (use both a quality of service mechanism such as DiffServ and MPLS virtual circuit-based switching). Asynchronous Transfer Mode networks - filling the managed multiservice core network role, but are being supplanted by MPLS networks. Frame Relay - intended to provide the core connections between local area networks to create wide area networks.Characteristics of Evolving Networks

Evolution of Service ArchitecturesA service architecture is an arrangement of computing elements, control logic, data and communications protocols intended to support a service or category of services.In the service and application areas, we are concerned with the generic control of connections and the logic to created value-added services.Characteristics of Evolving Networks

Evolution of Service ArchitecturesCharacteristics of Evolving NetworksEvolution paths for call control, services and applications

Dealing with ComplexityUse of levels for describing a GSM system

Dealing with ComplexityModelling is a formal way of describing the system or object of interest that ensures a consistent description for a specific purpose.Abstraction hides unnecessary detail of the system or object of interest, exposing only the detail required for the purpose at hand.

Dealing with ComplexityIllustrating the process of abstraction applied to physical components, namely links, in circuit- and packet-switched networks

Dealing with ComplexityIllustrating the process of functional abstraction applied to physical components, namely switches and routers, in circuit and packet switched networks.

A Framework for Modelling and AbstractingEvolving NetworksClassification of methods used for describing an ICT system

A Framework for Modelling and AbstractingEvolving NetworksAn ICT system is viewed as made up from building blocks that are structured to create the system physical entities (PE) functional entities (FE). Physical and functional entities are different types of views on system constituents.

A Framework for Modelling and AbstractingEvolving NetworksStructure of the ICT system the way the building blocks are arranged and grouped to reduce the complexity of the description.Methods used to describe ICT systems:Layers describe any hardware and software functional groups with clientserver type relationships.Domains - corresponding to related functions or administrative responsibilities. Planes - generally, but not always, peer-to-peer or user-to-provider relationships exist between domains within a layer.

A Framework for Modelling and AbstractingEvolving NetworksLayering is a method of partitioning an ICT system that identifies separations of functionality into subsystem where any two adjacent sections have a clientserver relationship. One subsystem, usually depicted as the lower layer, provides services that can be requested by the other, depicted as the upper layer. Each layer has characteristic functionality that is not generally found in another layer.Functional entities do not straddle layers while physical entities may do so. Inter-layer relationships are represented by reference points, applications programming interfaces or protocol service access points.Layering

A Framework for Modelling and AbstractingEvolving NetworksLayering Four established methods of using layering to manage complexity

A Framework for Modelling and AbstractingEvolving NetworksLayering Layers used for partitioning ICT systems with reference points

A Framework for Modelling and AbstractingEvolving NetworksLayering Application Layer: the locus of ICT application logic that may be in the telco or in an application service provider (ASP) domain.

2. Service Control Functionality (SCF) Layer: the locus of generic, stable and robust functionality to support realtime and information services using network connectivity. This layer is accessible to the Application layer through an open, secure API.

3. Resource Control and Management Functionality (RCMF) Layer: is the locus of functions that allow fulfillment of requests from the SCF layer for stream flows, messaging and access to network data in the transport layer. Functionality in this layer may relate to the control of resources for individual service instances or the broader management of resources. Resource control functionality (RCF) is a subset of the RCMF layer functions.

A Framework for Modelling and AbstractingEvolving NetworksLayering 4. Switching Control and Management Functionality (SCMF) Layer: the part of the transport layer concerned with routing of flows at the packet level and making physical connection to resources and gateways. Aggregate flow, per flow and best effort mechanisms are in general supported. This layer may similarly have service instance related control functions or broader management functions.

5. Transmission Control and Management Functionality (TCMF) Layer: provides the means of carrying high volumes of packets as well as TDM streams between elements such as switches. Control and management of this layer does not take into account individual flows. Functions in this layer are predominantly management functions.

A Framework for Modelling and AbstractingEvolving NetworksLayering Illustrating aspects of the definitions of SCF, RCMF and Switching layers

A Framework for Modelling and AbstractingEvolving NetworksLayering NGN Framework layers and sub-layers, with examples

A Framework for Modelling and AbstractingEvolving NetworksLayering Recasting content as a serving resource

A Framework for Modelling and AbstractingEvolving NetworksDomains A functional domain is one in which a related set of distinctive technical functions is performed in one or more layer.

The functions may be technical, business or regulatory. Business, administrative and regulatory domains in general span one or more functional domain. A domain may cut across some or all of the layers.

A Framework for Modelling and AbstractingEvolving NetworksDomains Layers and functional domains used for partitioning resources and functional areas of facilities

A Framework for Modelling and AbstractingEvolving NetworksDomains Technical functional domains (TFD) : The Customer Premises TFD accommodates terminals and, if present, customer premises networks which must interwork with the telco network infrastructure via an access network.The Access Network TFD represents the circuit- or packet-mode transport from the CPE to the edge of the network, supported by transmission and resource control.The Edge TFD is the point at which network-wide switching or routing begins and the user accesses network services. In the PSTN case, we regard the end exchange as an edge element. In a packet network the edge elements could be paired IP routers.

A Framework for Modelling and AbstractingEvolving NetworksDomains The Core Network TFD provides edge-to-edge transport, using one of a number of switching/routing paradigms. In fixed networks, core network functions have originating, transit and terminating roles. Mobile networks distinguish additional network roles including home network, visited network and serving network.The Gateway TFD accommodates elements between two networks performing a transport, signalling or media adaptation function. A gateway may have admission control and may generate accounting information.

A Framework for Modelling and AbstractingEvolving NetworksDomains Inter-network gateways appear between core networks, for example the Gateway MSC in a GSM network. A media gateway (MG) adapts the bearer traffic between switched circuit and packet networks and maintains connections between packet- and circuit-mode bearers. A signalling gateway adapts control and management messages from one protocol stack to another. Service Control Points are joined by an interworking function. A residential gateway (RG) may occur between the CPE and the access network. In general, an access gateway occurs where an access network meets the Edge.

A Framework for Modelling and AbstractingEvolving NetworksDomains Technical functional domains are often grouped into administrative domains. For example a telephone connection may pass through an originating network, one or more transit networks and a terminating network. Each network is the responsibility of a particular telco and is referred to as an administrative domain.

A Framework for Modelling and AbstractingEvolving NetworksDomains A business functional domain is usually mapped onto a representation of the ICT system by layer and technical functional domain.

Business domains have been vertically integrated.

Both technological and regulatory changes are leading to new forms of business domains.

With convergence, the traditional divide between telecommunications, information services and entertainment starts to disappear.

Similarly, the end-to-end paradigm of the Internet and the centralised service paradigm of telco networks are not the only models.

A Framework for Modelling and AbstractingEvolving NetworksDomains A regulatory domain is the area in which a regulator applies a particular set of policies and regulations.

A broadcast regulator treated the broadcaster and the signal distributor separately.

A telecommunications regulator may have treated fixed and mobile networks separately.

In general, new types of regulatory domains can be drawn on the backdrop of the layer-technical domain grid using the interlayer and inter-technical domain boundaries.

A Framework for Modelling and AbstractingEvolving NetworksPlanesThe concept of a plane is used to capture a crosscutting concern.

A plane is defined by selecting entities that relate to the particular concern from the two dimensional field of layers and technical domains.

The control application and its supporting protocol stack are termed the Control Plane.

The user application and its information transfer protocol stack form the User Plane.

The Operations, Administration and Maintenance System (OAM) in ISDN must interact with all protocol layers to ensure proper operation. The Management Plane is depicted as cutting across all layers of both protocol stacks.

A Framework for Modelling and AbstractingEvolving NetworksPlanesProtocol stacks showing ISDN-style Control, User and Management Planes

A Framework for Modelling and AbstractingEvolving NetworksPlanesThe Control Plane reflects all actions required to initiate, control and terminate calls and services. These actions are viewed in the NGN Framework at the application level.

The Data Plane encompasses all data resources needed to deliver a service.

The Management Plane encompasses all concerns of businessand operations support.

The Signalling and Distribution Plane (S&DP) reflects the fact that any ICT system is essentially distributed across space and is controlled and managed by processes hosted on different computing nodes communicating over a network. Signalling is not allocated to an explicit layer: signalling cuts across layers.

A Framework for Modelling and AbstractingEvolving NetworksPlanesLayers and planes used for partitioning resources and functions

A Framework for Modelling and AbstractingEvolving NetworksSummary of the NGN Framework1. The five layers provide the basic horizontal organisation of the framework. Layers have a client (upper)server (lower) relationship. It is recommended that the layering scheme be followed with possible variations. Sub-layers may be introduced provided that they also have a clientserver relationship. Only those layers relevant to a particular ICT system need be used. Layers may be merged if there is no benefit in exposing the interlayer interface.

2. Physical entities represent the typical physical building blocks of an ICT system. A PE may straddle layers.

A Framework for Modelling and AbstractingEvolving NetworksSummary of the NGN Framework3. Functional entities represent grouped functionality that resides within a single layer.

4. Technical functional domains reflect groups of related functionality/ across layers. A TFD may cross one or more layer. The choice of TFDs, CPE, Access, Edge, Core and Gateway, avoids physical and functional entities falling on a business or regulatory domain boundary.

5. Inter-TFD and inter-layer boundaries are useful in drawing the boundaries of business, administrative and regulatory domains.

6. Selection of functional entities across layers and technical domains that relate to a particular concern is a plane. The following planes are recommended: Control, Management, Data and Signalling and Distribution. Otherwise the list of planes is open-ended.

Examples of Application of FrameworkLegacy Networks Elements in the FrameworkMapping of legacy PSTN/IN physical and functional entities onto NGN Framework

Examples of Application of FrameworkFrom Circuit Switch to SoftswitchIllustrating the effect of locking call control to switching node in acircuit-switched network

Examples of Application of FrameworkFrom Circuit Switch to SoftswitchSeparation of softswitch-based call control signalling and media transfer in packet network

Examples of Application of FrameworkConceptualising Convergence in Layered ModelServices and applications is an area of considerable potential convergence. Legacy service control in switched circuit networks is based in the switches and in external IN platforms. The telephony network is a closed network: only the telco can offer services. The end-to-end model of the Internet is open since all intelligence resides in end stations and the network provides only packet transport. Anyone can provide services.

Examples of Application of FrameworkConceptualising Convergence in Layered ModelOpen network or Open Service Access (OSA) models for allowing applications to access network functionality are embodied in standards such as OSA/Parlay and JAIN. Similarly, the Parlay X standard seeks to allow the creation of Web Services that can invoke well-defined communications functions. These developments create a convergence between IT applications, Web services and telecommunications networks.

Examples of Application of FrameworkConceptualising Convergence in Layered ModelPoints of integration and diversity of access networks

Examples of Application of FrameworkConceptualising Convergence in Layered ModelHorizontal model for convergent environment with typical elements assigned to layers

Examples of Application of FrameworkDigital Video Broadcasting in the FrameworkDigital Video Broadcasting (DVB) encompasses standards for encoding, multiplexing and distributing digitally encoded signals.

Several distribution modes are described in various standards: satellite (with master antenna and cable distribution), terrestrial radio, cable and multichannel multipoint distribution systems (MMDS).

Digital video broadcast distribution networks offer significant broadcast downlink capacity in the undirectional broadcast channels.

Examples of Application of FrameworkDigital Video Broadcasting in the FrameworkReference model for Digital Video Broadcast systems overlayed on the NGN Framework. The interaction channel is carried a separate network.

Examples of Application of FrameworkDigital Video Broadcasting in the FrameworkReference model for Digital Video Broadcast systems overlayed onthe NGN Framework. The interaction channel is carried in the same network as the broadcast channel.