Lucent SoftSwitch

____________________________________________________________________________________________________

1 Lucent Technologies

An Introduction To The

Lucent Technologies SoftswitchEnabling the Promise of Next Generation

Converged Networks

June 16, 1999 Lucent Technologies, Inc.All rights reserved.

Lucent TechnologiesBell Labs Innovations

____________________________________________________________________________________________________


This paper discusses Lucent Technologies SoftSwitch, a revolutionary softswitchapproach to the Next Generation Network and how you can satisfy the need forrapid creation and deployment of new services and efficiently integrate IPtelephony and PSTN technologies.

Abstract

____________________________________________________________________________________________________


Today voice and data networks coexist, with an approximate equal amount oftraffic; however, data traffic rates are growing at rates 10-15 times faster thanvoice. In 1999, one-third of homes will be on-line. Electronic commerce willincrease to $400 Billion in the year 2000 up from $12.5 Billion in 1997, predictsIDC. This general business application will lead to an increasing usage ofmessage delivery. The Internet is becoming the network of choice for thedistribution of voice and data. In this changing environment, market drivers are:

q Deregulation is creating new and competitive telephony environments formany new and specialized service providers in voice as well as datatransport.

q Service providers are creating new servicesfueled by the increasing use ofpacket networks

q IP usage is increasing at a dramatic rate, causing bandwidth problems onexisting PSTN networks carrying data.

q Convergence of PSTN and packet networks to allow end-to-end delivery, is agrowing requirement.

With these market drivers, the Internet and packet-switching will evolve into theNext Generation packet network.

The next generation network will be an evolution of todays PSTN and IPnetworks. There are many dilemmas facing service providers as they evolvetheir strategy to reach that juncture. Many advanced service offerings requireubiquitous interconnectivity, which is the ability to call from any telephonyendpoint to any other endpointanywhere. The world is not so simple anymorewith many different kinds of telephony endpoints. For example, there are analogand ISDN telephones, personal computers running H.323 applications andworkstations running SIP (Session Initiation Protocol) applications, to name justa few.

Interworking all telephony endpoints is currently not feasible because many ofthose endpoints speak different, incompatible protocols. For example,NetMeeting speaks a variant of the H.323v1 standard, whereas a Mediatrixclient speaks SIP; these protocols do not interoperate. Thus, it is impossibleusing currently available technology to place a call from NetMeeting to aMediatrix client that only supports SIP. Even endpoints that claim to speak thesame protocol often speak different variants of that protocol, and hence do notinteroperateand PSTN uses SS7 signaling technology, totally foreign to IPnetworks.

New service creation and the integration of existing IN telephony services intonext generation networks compounds the service providers dilemma evenfurther. Next generation networks must provide for a seamless access to existingIN telephony services to preserve a source of revenue as well as assisting thedissimilar network integration. Additionally, there is the problem of

Section 2.0

The ServiceProvidersDilemma

Section 1.0

The TelephonyMarketEnvironmentToday andTomorrow

____________________________________________________________________________________________________


adapting/integrating new services. With the telephony marketplace becomingmore competitive, next generation networks must provide the ability to integratenew services from any source, local or remote, to meet market demands of theever changing workplace and provide a method of differentiating one serviceprovider from another.

To meet these interoperability demands and to provide differentiation in themarketplace, a service provider has to consider how to:q provide ubiquitous interconnectivity across PSTN and IP networks,q provide new, advanced services, deployed faster,q eliminate concerns about the underlying network configuration,q better exploit government tariffs domestically and internationally, andq use existing network resources more efficiently.

IP telephony offers only a partial solution. Current IP telephony does not enableubiquitous interconnectivity. It does not enable rapid creation of new advancedservices or integration of existing IN services. Furthermore, gateways fromdifferent vendors do not interoperate.

The Lucent Technologies Softswitch is a revolutionary softswitch platformcreated by Lucent Technologies. The Lucent Softswitch provides:

q open standardized protocols which connect distributed hardware andsoftware,

q seamless interconnection between both the transport and signaling networksof IP and traditional telephone networks, and

q an open standardized application development environment

The Lucent Technologies Softswitch acts as a software switch integrating bothPSTN and IP networks while leveraging existing investments in billing systems,management systems services and applications.

Developed by Bell Labs for network service providers, the Lucent Softswitchallows telephone and Internet telephony subscribers to enjoy seamless, richinteroperability between previously isolated islands of telephony/IPconnectivity. The Lucent Technologies Softswitch is also an open servicecreation architecture, which dramatically changes the way new services can bedeveloped and then integrated into a service providers environment. Java-based APIs will allow the rapid development and deployment ofapplications/services. Service Providers will be able to write their own serviceapplications, or utilize service applications developed by Lucent or third partyvendors.

The Lucent Softswitch sets up point-to-point communication across IP and PSTNnetworks by providing interoperability between SS7 signaling and IP protocols.It allows PSTN calls to be terminated on different IP telephony networks; it

Section 3.0

Lucent TechnologiesSoftswitch Overview

____________________________________________________________________________________________________


allows IP telephony network calls to be terminated on PSTN networks.Signaling interoperability is important because it provides interoperabilitybetween Internet Telephony Gateways from multiple vendors. This benefits bothconsumers and service providers. Consumers expect the same ease of use,functionality, and QoS they are accustomed to and service providers, who need aplatform on which to base their convergence strategy.

The Lucent Technologies Softswitch architecture achieves interoperability andnew service creation capabilities by encapsulating those functions in a specificset of Lucent Softswitch components, thus hiding the details of signalingprotocols from the service creation activity. An immediate application of theLucent Technologies Softswitch is to achieve interoperability among most of thecircuit-packet gateways currently on the market, which is a significant enoughreason to deploy this architecture. But, it is the service creation environmentprovided by the Lucent Softswitch that will change the way services are createdand deployed.

Figure 3.1 The Lucent Technologies Softswitch Functional Architecture

New and unique service offerings hold the promise of increased revenue anddifferentiation for service providers.q New applications that integrate voice and IP services are possible with this

infrastructure. For example, integrating Internet Call Waiting with Text toSpeech/Speech Recognition applications is easily achieved using the LucentTechnologies Softswitch platform.

q Cost effective large-scale aggregation of modem terminations allows serviceproviders to offer managed modem services to smaller ISPs as well asenterprises. Smaller ISPs and enterprises do not have to own and manageRemote Access Servers.

q Aggregated DS1/DS3/OC3 connections running IP between the Data CLECand the ISP/Enterprise allow for private network routing (for security andguaranteed performance) and public Internet routing.

LUCENTTECHNOLOGIES

SOFTSWITCH

SS7 Net

Access/TrunkingMedia Gateway

Access/TrunkingMedia Gateway

IPBackbone

TDM

IP IP

SCPServices andapplications

ManagementSystem

BillingSystem

TDM

GatewayControl

Protocols

GatewayControl

Protocols

____________________________________________________________________________________________________


q SS7 co-carrier trunks (Inter Machine Trunks) offer a way to divert modemtraffic from the core circuit network.

q Offering services like virtual private networks, local number portability,calling card, and 800 or toll free numbers through the Lucent TechnologiesSoftswitch TCAP interface to SCPs and circuit/packet intelligent peripherals.

q Recreation of PSTN services through Lucent Technologies Softswitchservice provider servlets, feature applets, and software development kits inJava.

The Lucent Technologies Softswitch is a software platform. The LucentSoftswitch does not require any special-purpose hardware. All the LucentSoftswitch software runs on general-purpose computers, such as Sparcworkstations running Solaris 2.6.1.

q The Lucent Technologies Softswitch interworks telephony protocolstransparently. The Lucent Softswitch provides a software platform fortrunking and access gateways and remote access servers. It is aprogrammable, software switch that translates between different signalingsystems (SS7, SIP, H.323, Q.931, etc.). Also supported are SS7 to SS7 overIP and IP to IP with different protocols over IP. To implement a newtelephony service in the Lucent Softswitch, it is not necessary to understand,or even be aware of, the multitude of telephony protocols that exist in theunderlying network. The functionality of Lucents SoftSwitch is shown inFigure 3.1.

q The Lucent Technologies Softswitch has extensive call processingfeatures. It provides primary inter exchange carrier signaling support aswell as co-carrier signaling support. Routing features include least costrouting, percent allocation based routing, prioritization of trunk groups, andsubscriber specific features to name a few.

q The Lucent Technologies Softswitch is based on Java. LucentTechnologies Softswitch APIs are defined entirely in the Javaprogramming language. Furthermore, most of the Lucent TechnologiesSoftswitch implementation is also written in Java. Use of Javaautomatically incurs the benefits that Java brings to every software systemin which it is used. In particular, the Lucent Technologies Softswitch isportable, robust, easy to program, and incrementally loadable. This willdramatically reduce the complexity of adding new services.

q The Lucent Technologies Softswitch has a distributed architecture. TheLucent Softswitch software entities can be distributed across multiplehardware entities operating as a single software switch. It is completelytransparent to any Lucent Softswitch entity whether another entity withwhich it is communicating is on the same or a different host in the network.Hence, Lucent Technologies Softswitch entities can be distributed arbitrarily

Section 3.1

Features andCharacteristics

____________________________________________________________________________________________________


in the network, to satisfy both load-balancing and administrativerequirements.

q The Lucent Technologies Softswitch utilizes existing directories. TheLucent Technologies Softswitch can leverage existing PSTN and IPdirectories to take advantage of existing applications and services.

q The Lucent Technologies Softswitch is scalable. It utilizes a distributedcluster architecture for large-scale call processing needs. If an entity in aLucent Technologies Softswitch network begins to reach capacitylimitations, another copy of that entity can be added to the network, therebyoffloading the overloaded entity.

q The Lucent Technologies Softswitch is easily deployable and offersinvestment protection. Adding a new service, or support for a newtelephony protocol, to a network that contains the Lucent TechnologiesSoftswitch requires only the incremental addition of a few software entities.Rarely is it necessary to completely replace any existing software orhardware in the service providers network. Further, adding new services,support, or gateway types for a new protocol rarely requires modification tothe non-Lucent Technologies Softswitch entities in the service providersnetwork.

q The Lucent Technologies Softswitch has extensive management features.It employs policy server based management that is directory enabled. Everysoftware entity exposes a management interface that is aggregated. LucentTechnologies Softswitch entities are SNMP manageable with support fromcommercial network management tools.

q The Lucent Technologies Softswitch supports a host of back officefeatures. These include a programmable event detail recording facility, calldetail records and events as well as routing tables used by provisioning tools.

q The Lucent Technologies Softswitch has extensive reliability features. Ithas an active backup for each Call Coordinator and Device Server. Itemploys a policy initiated auto restart of the software entities upon thedetection of faults.

The Lucent Technologies Softswitch functional architecture consists of acollection of communicating software entities, which combine to provide aunique service creation environment and interoperability platform. There areseveral patents pending on the Lucent Technologies Softswitch componentsshown in Figure 4.1. To a large extent, the Lucent Technologies Softswitchprovides a holistic approach to service creation, meaning the combinedfunctionality is greater than the sum of its individual parts. It is used to connect

Section 4.0

Lucent TechnologiesSoftswitchArchitecture

____________________________________________________________________________________________________


PSTN and IP networks and performs all protocol conversions and dataadaptations. Each of the individual components are discussed below, followedby a general discussion of how the components communicate with each other andcombine to form the total Lucent Technologies Softswitch system.

Figure 4.1 Lucent Technologies Softswitch Functional Software Components, inan IP/PSTN System Environment

q Call Coordinators. A call coordinator is an object that manages the overallflow of events involved in one or more sessions. The call coordinatormaintains information for each call that it is managing. This consists ofprocessing service-specific control events that may be generated by the useror the terminal. This information includes, for example, the set of userfeature applets, a service provider servlet, and device servers, utilized in thecall. This information is represented as a common namespace that the callcoordinator exports, and hence is available to any interested software entity.

q Device servers. The device server modules allow communications betweenvarious network elements using different protocols. For example, anH.323v1 device Server is used to connect H.323v1 end points; an SS7 device

User FeatureApplet

Directory Coordinator

OracleRDBMS

LocalSwitch

SS7 DeviceServer

H323 DeviceServer

SS7 DeviceServer

LocalSwitch

TrunkingGateway

IPDC on TCP orMGCP 0.1 on UDP

H.323v1/v2(on TCP)

ISUP(SpecificCountryVariant)

ISDN PRI orT1 (wink, e&mEtc.), TDMG.711

TDMG.711

RTP/UDP/IP G.711

LUCENT

SS7 NetSS7 Net

Service ProviderServlet

Call Coordinator

Mantra(on TCP orDIAMETER/UDP)

SIP DeviceServer

POTSPhone

POTSPhone

IPPhone

SIP( on UDP or TCP)

IPDC on TCP orMGCP 0.1 on UDP

AccessGateway

(GW1000)

TrunkingGateway(PVG)

LDAPDirectory

SCPAccess

PolicyServer

____________________________________________________________________________________________________


server speaks to SS7 devices and so on. Any Lucent TechnologiesSoftswitch system may utilize one or more device servers for each differentprotocol/ gateway it needs to address. Communication to these gateways isencapsulated in the Lucent Technologies Softswitch device server, isolatingthe need for other components of Lucent Technologies Softswitch to beaware of the protocol. Integrating different vendor gateways is done byadding a device server for that gateway without impacting any other part ofthe Lucent Technologies Softswitch.

q User feature applets. A Lucent Technologies Softswitch user feature appletis the object that represents a participant in a call; the user feature appletimplements the service logic associated with that participant. As an example,a user feature applet would bring in feature applets/services requested by thecaller. A user feature applet can support rules for processing informationbased on the calling number, caller number, time of day, day of week, etc.This allows third parties to create services and offer them through a serviceprovider. The service provider interfaces the user feature applet and chargesfor traffic that utilizes this service. Both third parties and service providersbenefit from this arrangement, and so do the consumers or enterprises thatselect these services.

q Service provider servlets. A Lucent Technologies Softswitch serviceprovider servlet is an object the service provider implements to customizetheir service offer. For example, by programming the service providerservlet, CLECs can customize the behavior of the Lucent TechnologiesSoftswitch to route traffic through different carriers during different times ofthe day to take advantage of least-cost-routing policies negotiated withmultiple service providers. Each service provider will create differentimplementations of the server provider servlet for their individual needs.Since programming the servlet is relatively simple and can be changedwithout disruption to the system, as better rates are negotiated or otherchanges occur, service providers can quickly adapt their servlet andimmediately begin to see the cost savings. The APIs for both the user featureapplet and service provider servlet will be supported with softwaredevelopment kits.

q Directory Coordinator. The directory coordinator is used to communicateto the different directories required for both PSTN and IP networks. SCPdatabases, LDAP, and any SQL databases are all supported. By having adirectory coordinator or Meta Directory, other components are not requiredto interface to the directories for the information they need. Addingadditional directories has relatively no impact on the rest of the system.

q Policy Server. The policy server monitors all management events in theLucent Technologies Softswitch platform and maintains control over allelements. In particular, the policy server monitors the health of all LucentTechnologies Softswitch components, maintains configuration informationfor all Lucent Technologies Softswitch components, and collects the trapsfrom all Lucent Technologies Softswitch components. The policy server alsopresents the management portal for the administrators into the LucentTechnologies Softswitch platform. As such, the policy server can be scripted

____________________________________________________________________________________________________


to filter/correlate various traps, notify other processes about registeredevents, support custom failover policies, etc.

The Lucent Technologies Softswitch is based on the innovative MantraTechnology from Bell Labs. Mantra is a call signaling model and associatedmessage sets, that enables switching and processing to be fully distributedacross a network. The Mantra schema is supported by a lightweightDistributed File System (DFS) technology that efficiently enables individualfiles to be exported and mounted, just as directories are exported and mountedwith conventional DFS implementations.

The use of Mantra dramatically reduces the complexity of communicationbetween Lucent Technologies Softswitch entities and thus is yet another factorin reducing the time it takes to implement new services.

The Lucent Technologies Softswitch provides three related application-programming interfaces (APIs); all are written in the Java programminglanguage. They are:

q The Directories API. This API allows service providers or third parties toimplement interfaces into their directories.

q The User Feature Applet API. This API allows ISVs or service providersto implement new feature applets.

q The Service Provider Servlet API. This API allows the service provider tocustomize their Lucent Technologies Softswitch network for their ownoptimization.

This white paper is only a brief introduction to the Lucent TechnologiesSoftswitch. For more information, visit our web site at:

www.lucent.com/pipsp

NetMeeting is a trademark of the Microsoft Corporation

PacketStar is a trademark of Lucent Technologies, Inc.

Java, Sparc, Solaris are trademarks of Sun Microsystems, Inc.

Section 4.1

Mantra Technology

Section 4.2

ApplicationProgrammingInterfaces

Documents

Lucent SoftSwitch