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Voice and Data Network Convergence and the Applicationof Voice over 1P

John M. ElchidgeAdvanced Network Integration Department

Sandia National LaboratoriesP.O. BOX 5800

Albuquerque, NM 87185-0806

AbstractThis paper looks at emerging technologies for converging voice and data networks andtelephony transport over a data network using Internet Protocols. Considered are thebenefits and drivers for this convergence. The paper describes these new technologies, “how they are being used, and their application to Sandia.

Table of Contents

Introduction .....................................................................................................................5Background .....................................................................................................................6

Telephone Installation .................................................................................................6Data Installation ..........................................................................................................7

Requirements and Areas of Inte~ation ...........................................................................8Functional Integration .....................................................................................................9

Synergistic Services ....................................................................................................9Operations ................................................................................................................. 10

Voice over IP Telephony ............................................................................................... 11Gateways ................................................................................................................... 11“LAN” PBXs ............................................................................................................. 12Encoding .................................................................................................................... 13VOIP Standmds .......................................................................................................... 15

Lucent 7 R/E Switch ..................................................................................................... 16VOIP At Smdia .............................................................................................................. 17

Security -- .................................................................................................................. 17Scalability . . .............................................................................................................. 17Availability/Reliability -- .......................................................................................... 19

Recommendations .........................................................................................................2lSummary .......................................................................................................................23References .....................................................................................................................25Distribution ...................................................................................................................26

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Introduction

Technological innovations and industrydevelopments in telecommunicationshave recently generated substantialinterest in combining voice and datanetworks. Numerous articles,presentations, and companyannouncements [Cas][And][Ren] [BCR]have addressed this topic. Manufacturersthat have historically producedequipment for either the data or thetelephone markets are attempting tobroaden their product lines to serve bothmarkets. This paper explores how thesedevelopments might apply to Sandia’senterprise operation.

There are several drivers for wanting tocombine these networks. They areexpected lower cost structure andincreased system efficiencies, regulatorychanges, the development and maturingof underlying technologies thatfacilitates service convergence, and thepromise of new customer applicationsthat would not otherwise be possible.

Cost/E fjfciency --The demand forreduced costs and more leveragedspending is a major driver in consideringconverged telecommunication networks.Telephone and data networks requirelarge capital outlays to build out cable,switching, and distribution equipment.Lnaddition to the initial infrastructurecosts, there are large costs in maintainingthe networks and providing ongoingservices. Telephone and data networksshare many of the same structuralelements. Both networks require inter-building cabling, intra-building cabling,switching equipment, reliable powersystems, equipment maintenance, andcustomer services. The two networks

require common structural elements,however, the implementations of theseelements are unique to each network.This leads one to believe that combiningthe networks can reduce cost andcomplexity by removing redundantoperations and by reducing the numberof unique operations.

New Applications -- User needs forapplications that combine voice and dataservices are emerging. One area ofstrong interest is in customerrelationship management, particularly incall centers or help desks. The ability toaggregate and integrate all aspects of thecustomer-supplier interaction makes forbetter and more successful outcomes.Another area is telecommuting or remoteaccess. It is desirable to be able todeliver identical communication servicesto the end user regardless of location.Voice and data integration allows formore user control over the call processand the ability to handle or screen callsin ways that are not otherwise possible.

Regulatory --National legislation and themove to deregtdate thetelecommunications industry are leadingcompanies to look at different modelsfor providing telecommunicationservices. The distinction between localphone, long distance and data serviceproviders is disappearing as companiesattempt to provide customers with allservices from a single vendor.Traditionally governments andregulatory agencies have placedsignificantly different excise taxes andaccess charges on differenttelecommunication services. Thesedifferences have created imbalances inthe cost structures for voice and dataservices with the result that companies

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have made implementation changes totake advantage of the cost differences.“These regulatory factors have aninfluence on Sandia’s public networkaccess.

Technology --Technological change ismaking it possible to consider alternativemethods for deployingtelecommunication services. Thedevelopment and growth of datanetworks, both Intra-net and Internet,has been to such an extent that thebandwidth requirements for datatransport is exceeding that required forvoice ~n] [Min]. As the available datanetwork bandwidth grows, it becomespossible to include voice traffic withoutsubstantially increasing data networkbandwidth requirements. Further, digitalsignal processors have progressed to thestage where they have sufficientprocessing power at a low cost to alloweffective digitization and coding of voicesignals for transport over packet and cellnetworks. These developments areenablers, that allow one to implementconverged networks.

The innovation exhibited by anddeployment of new services on theInternet is spurring innovation intelephony equipment. Service providersare pushing for the replacement ofproprietary telephony equipment withequipment built to open standards,common software tools, andprogramming interfaces.

Background

Telephone Installation

In the early 1990’s, Sandia National ,Laboratories, SNL, installed a central

office class telephone switch at itsAlbuquerque campus. This telephonesystem, with a Lucent Technologies5ESS switch at its core, employs atypical telephone system architecture.main, centrally located, switch fabricprovides all the control and switchingfunctions for the system. Telephonesindividually attach to the switch via

A.

twisted wire copper cables. Because ofthe large geographic dispersion ofphones across SNL technical areas, the5ESS is configured with opticallyconnected remote modules to placeswitching equipment closer to telephoneusers. When a user makes a telephonecall, the switch allocates bandwidth anddedicates that bandwidth to that user forthe duration of the call. The switchcompletes all call functions andbandwidth management within itsboundaries. Likewise the central switchprocessors route calls to or from otherswitches over interconnecting trunks.Sandia’s telephone switch, like mosttelephone switches, is proprietary indesign. While there are certain common,standardized interfaces, the switchingfabric, software, circuit packs, and otherparts of the switch are unique. Figure 1below graphically illustrates the existingswitch layout.

Commercial telephone companies haveused the above described systemarchitecture for many years and foundthat operation of such a system lendsitself to certain maintenance andoperations activities. SNL has adoptedmany of these commercial practices forproviding telephone services. Day-to-day operation of the system clustersaround the operation of the variouscomponents of the system -- switching,outside cable plant, inside cable plant,

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Sandia 5ESS Telephone SystemAlbuquerque, NM

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move/add/and change activities,customer service requests, and troubleresolutions. Each operational arearequires people with different skill setsto perform unique tasks that arenecessary to make the system function.

Data installation

Sandia maintains and operates severaldata networks that are grouped bysecurity environment. The generalnetwork design within each securityenvironment is similar to that ofnetworks in other environments. Thenetworks fall within the Sandia OpenEnvironment, SOE, the SandiaRestricted Environment, SRE, and theSandia Classified Environment, SCE.

Within each of these environments,Sandia maintains a corporate network.Respectively they are the Sandia OpenNetwork, SON, the Sandia RestrictedNetwork, SRN, and the SandiaClassified Network, SCN. Otherdepartmental or programmatic networksmay also exist within these securityenvironments.

San&a’s data networks have evolvedthroughout the 1990’s to support aninterconnection of local area networks.The fabric interconnecting the LANs is ageographically distributed collection ofswitches and routers. There are dozensof autonomous devices that inter-operatewith each to form the building blocks of

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Figure 2 -- Data network installation

the network. Each device executes itown version of firmware, software, andconfiguration settings. Switches androuters are composed from multiplemakes andlor models as necessary toprovide the desired functionality.

While the detailed network architectureand interconnection methodology variesfrom one part of the network to the next,there is a general hierarchical layout towhich the network conforms. Figure 2shows this layout. At the network coreis a mesh of asynchronous transfermode, ATM, switches that transfertraffic between the differentgeographical sectors of the networkAlso at the core is a group of routers thatprovide general, network wide routingfunctions. A secondary group of ATMswitches and routers, located at sectordistribution facilities, support the users

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in the nearby buildings. Within eachbuilding are one or more distributionareas with local Ethernet and/or ATMswitches that provide that networkterminations to the buildings users.

Requirements and Areas ofIntegration

In considering voice and data networkintegration, Sandia faces many of thesame issues and concerns that face otherorganizations. These concerns are basedin a number of system requirements thatthe telephone system must address.Requirements derive from serviceprovider and end customer concerns.

From an end customer perspective, thetelephone system must promote voicecommunications within Sandia, andbetween Sandia and others around theglobe. The service must work as.

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expected by the customer. It must meetthe customers’ reliability expectations.New services and service changes mustbe delivered within a certain time. Thetelephone system must provide sufficientfeatures and functionality to make abusiness difference to Sandia as a whole.A growing requirement is to meet themobility and flexibility needs of ourcustomers. Customers expect that theservice will be available when they wantit.

Cost containment or reduction, ifpossible, is a strong driver of thetelephone system and itsimplementation. However, it is not theonly or necessarily the leadingrequirement. Rather, other customerrequirements need to be met at anaffordable price. In many respects, costto provide service is a service providerrequirement since the end customer is farremoved from the funding process.Other service provider requirementsinclude complexity reduction, flexibilityto provide services when and where theyare needed both on and off campus, andmaintenance of interconnectivity andcompatibility with the public network.

Both the voice and data networksattempt to meet customer needs forrobust communication, informationsharing, and information dissemination.Each network evolved at different timeswith different technologies to meetdistinct modes of humancommunication. Increasinglyindividuals wish to communicateknowledge in more depth using a varietyof information modes. The manner inwhich people wish to communicate anduse information technology fosters theintegration of distinct voice and data

networks. There are benefits tointegrating the technologies upon whichthese services are built. However thegreatest benefit to the customer willcome from applications that integratedifferent communication services toimprove the ways in which peoplecommunicate or conduct business.

Voice and data networking evolved atdifferent times and use differenttechnologies, however, they sharecommon functional elements which lendthemselves to integration. Commonthemes between the two networksinclude switching/electronic systems,distribution including the cable plant,customer premises equipment, andoperational processes and procedures.Network integration may occur at any orall of these subsystems. The benefits ofintegration and the extent to which it “occurs is dependent on requirements andthe drivers for integrating the systems.

Functional integration

Synergistic Services

It is possible to integrate voice and datanetwork services without actuallyintegrating the underlying networks. Asan example of this type of integration,consider WEB dialing. With thisservice, a customer is able to usebrowser software on his or her networkconnected computer to locate someone’sphone number from an electronicdirectory. The customer is able to placea phone call to that person through theselection of a hyperlink tied to thatphone number. The customer benefitsfrom a streamlined process of locating aphone number and then placing a call tothat number. Other examples of

functional integration include datanetwork based facsimile transfer, datanetwork delivery and handling of voicemail, and call center applications.

In many cases, material that is faxedbetween locations is generated oncomputers connected to a data network.To transmit the material, it first has to beprinted, then the printed material carriedto a facsimile machine and transmitted.On the remote end, the material maybeconverted to an electronic format that ismanipulated on a computer. In thisprocess the telephone network provides astandardized, ubiquitous means formoving information. The availability ofa ubiquitous data network provides amore attractive alternative foraccomplishing some tasks. Facsimile isa case in point. In many cases at SNL,customers have replaced facsimiletransfers within the company with E-mail. When interacting with entitiesoutside of the company, E-mail is notalways an option in place of facsimile.

Voice mail has evolved to the pointwhere it provides a wide range offeatures for manipulating listening to,and handling voice messages. With theInteractive Voice Response, IVR,features of the voice mail system it ispossible to access data stored oncorporate computers. The voice mailsystem is an information store as well asit provides the customer the ability to usea telephone set as an access device toretrieve information from corporatedatabases. In some cases, the customermay find that a computer provides amore functional interface for handlingvoice information. The voice mail andE-mail systems are convergence pointsfor the integration of information and the

ability to access that information withdifferent tools depending on thecustomers’ preferences. .

Each of these applications makes use ofsynergistic functions of the voice and .

data networks. The strength of eachnetwork is leveraged to provide thecustomer a service that is morefunctional and easier to use than whatcould be provided by each networkalone. Consider the utility of anapplication that combines voicemessages, textual E-mail messages,video, as well as other data formats forcommunicating and storing information.When customers interact with eachother, it usual] y occurs at several levels.A phone conversation may occur; datafiles may be exchanged through E-mail;the customers may meet face to face.Ultimately customers will expect acommunication system that allows themto access, retrieve, and manipulateinformation of different types through avariety of interfaces.

Operations

In running separate voice and datanetworks, many of the operationalaspects of the two networks areduplicated. Eliminating this duplicationcan provide service delivery efficienciesand cost reductions. The operation ofeach network requires engineeringsupport, installation and maintenancecrews, procedures and processes fordelivering services, documentationsystems to track customer orders and thestate of the system, and mechanisms forservice restoration in the event of anoutage.

Because of the history of the twonetworks, customers have different

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expectations from each network. Thevoice network is expected to be veryreliabie and always available to a largerextent than the data network. The datanetwork is expected to be more

\ innovative in adapting to customerrequirements and available technology.These different expectations lead todifferent attitudes in the manner inwhich each network is implemented andoperated. Over time, customerexpectations for each network willconverge, and the operation of eachnetwork will need to adapt.

Voice over 1P Telephony

Voice transport over the IP dataprotocol, VOIP, has garnered abundantinterest lately. There are several reasonsfor this, but the main ones are the desireto reduce telephone system installationand operating costs and the push to movetelephony away from proprietaryarchitectures towards more openstandards. It is important to note thatVOIP is not the same thing astransporting voice over the intemet.VOIP and the intemet merely use thesame under-lying communicationprotocols. VOIP systems in a businessenvironment are built on privatenetworks, or inter-nets, to ensure servicequality.

While the overall market penetration ofVOB?systems remains small, thetechnology deployment growth as apercentage is high [Duk]. In early 1999,there were few companies and relatively*few products in the VOIP realm. Byearly 2000, all of the major

● telecommunication equipmentmanufactures either had VOIP productsavadable or were in iater stages ofdevelopment. Also, investors have

formed many new companiesspecifically to address the VOIP market.

There are several areas in which thetechnology is deployed and used inindustry today. The applications includeswitch to switch trunking, network basedprivate branch exchanges, PBX, callcenter applications, and mobiletelephony. Each area of use targetsdifferent customer requirements. VolP asit has arisen in the market takes twoforms. PBX to PBX gateways andnetwork based “PBXS.”

Gateways

The first use of VOIP has been for switchto switch trunking. Telephone trunks arethe interconnecting pathways that allowcustomers served by one telephoneswitch to communicate with customersin the public switched network or servedby other switches. Traditionally trunksare analog lines or an aggregation ofindividual voice channels over a TIcarrier facility. In the VOIPimplementation, the interconnectinganalog or T1 trunks are replaced with anIP network. Encoder/decoder units, orgateways, act as the interface betweenthe analog and T1 interfaces on thetelephone switch and the IP network.Many of the current generationgateways use Ethernet or ATMinterfaces to attach to the IP network.See Figure 3(a).

By compressing the encoded voice signalbefore transmitting it, switch to switchdata flow can be significantly reduced.Companies have made use of thisprocess to reduce the total voice and databandwidth between two locations. Ininstances where separate voice and datatransport facilities interconnect two

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PBX PBX GateKeeper

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Standard

Phones (b)

Figure 3 ---- VOIP System Implementations. (a) Switch to Switch TrunkAccess Gateways, (b) VOIP PBX with Gatekeeper, Line Access Gateways,and VOIP Phones.

locations and there is excess databandwidth, the use of VOIP gateways forthe voice interconnect may make itpossible to eliminate the separate voicetransport facilities. In this event, therewould be a corresponding cost decrease.Also reducing the amount and variety ofequipment that a company needs tomaintain and support between locationscan reduce costs. Organizations thathave significant voice and data traffic tofixed foreign locations have madeextensive use of VOIP gateways to thoselocations.

New telecommunication serviceproviders are designing and buildingnetworks from the ground up basedcompletely on IP packet transport. Level(3) Communications is one suchcompany. The operating premise of

these companies is that they can buildout IP networks that are simpler and lessexpensive to operate for providing bothvoice and data services. As thesecarriers deploy their networks morewidely, VOIP gateway access to thepublic switched network will becomemore common.

“LAN” PBXS

Another major area of Voll? technologydevelopment and implementation hasbeen in the deployment of “Network”PBXS. See Figure 3(b). In thisapplication, the IP network is theswitching fabtic for voice services.Other than for adaptation devices toprovide interconnectivity to the PSTN,there are no circuit switched elements inthe switching fabric. A network attachedserver, called a Gatekeeper, provides the

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services necessary for establishing atelephone call. It performs telephonenumber to IP address resolution. The,.—gatekeeper also provides the commonlyexpected telephone features such as callforwarding, call transfer, and callconferencing, as well as others. NetworkPBXS offer abundant possibilities forcomputer control of telephone callrouting, telephone call features, andvoice/data application integration.Typically once a telephone call isestablished, the gatekeeper is no longerrequired to maintain the connection.

The customer equipment also directlyattaches to the IP network and uses it forvoice transport. Customer equipmentmay take on a number of formats. At themost basic level may be an adapter, or ananalog access gateway, that translates theinterface of a standard telephone set to anetwork attached interface. The adapterprovides the means for encoding anddecoding the analog signal from thetelephone instrument into IP packets.The adapter may be capable ofterminating several to many analogtelephone sets. A variation on thistheme is what is called a “soft ITphone.” With a soft phone, a personalcomputer or w orkstation executessoftware that emulates the function of anaccess gateway. The software replacesthe telephone set with a computerinterface that emulates buttons andcontrols of a real telephone. Thecomputer’s sound card provides the

b

physical mechanism for encoding anddecoding the voice signal. Perhaps moresignificant is the development of II?

● phones. In essence an IP phone isnothing more and nothing less than aspecialized, single purpose computer.To the casual observer it looks like any

other telephone instrument with a body,a keypad, and a handset. The networkinterface is Ethernet, either 10 Base-T or100 Base-T. The IP phone makes itpossible to completely combine voiceand data infrastructures to the customerdesk.

Encoding

The transport of voice over an IPnetwork is accomplished through a seriesof encoding and packaging steps. Thegeneral process is as such. A transducerconverts the voice acoustical wave intoan analog electrical signal. Typically,VOIP equipment limits the bandwidth ofthe signal to 3.5kHz, as does atraditional telephone switch. Theencoder, or codec, then samples thesignal at discrete time intervals, usually8k samples/second and represents eachsample with 7 or 8 bits of data. Notethat each sample represents 0.125 ms ofthe voice signal. Hence the voice signalis correspondingly encoded into a 56 or64 kbitis data stream in each direction.This encoding process is called pulsecode modulation, PCM, and is specifiedin ITU standard G.711.

Modern digital telephone switches,including the 5ESS, use G.711 signalencoding for voice calls as well. Thedifference between a “circuit switchedtelephone switch, the 5ESS, and a VOB?system is the manner in which thesystem transports the data stream fromthe speaker to the listener. In a circuitswitched system, the switch establishesa dedicated channel or circuit betweentwo telephones during calling setup. If achannel is available, the switchconstantly transports data at a rate of 56or 64 kbitis between the two telephones.In the event that the switch can not

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Figure 4-- Voice Encoding andEncapsulation.

establish a channel between the twotelephones, then the switch presents thecaller a busy signal. In a circuit switchedsystem, once a channel is establishedthen there is a guaranteed fixedbandwidth, fixed delay, data pathbetween the two end points.

In a VOIP system, there is no explicitlydedicated channel between the two endpoints. Rather, the system encapsulatesthe encoded voice signal into adatagram, inserts the datagram into anetwork packet, and combines the packetwith those from other sources and sinks,and then transports the packet from thespeaker to the listener. Because there isno predefine bandwidth for a VOIP callchannel, it is possible to use codecs ofvarious bandwidths. In fact, this is onemanner in which it is possible for VOIYsystems to reduce telephone operating

costs. Speech signals contain muchredundancy. By removing thisredundancy, it is possible to compressthe bandwidth requirements needed totransport the voice signal. Also manytimes during a telephone conversationthere are periods when there are noutterances between the two callers. Bynot encoding these silent periods, it ispossible to further reduce the requiredbandwidth for the call. The ITU hasdefine several widely used compressingcodecs, including G.726, G.728,G.729/A, G.723. 1. Each of these codecsare “lossy” and make a tradeoff betweenvoice quality and bandwidth.

Figure 4 shows the network packetcreation process. After the codecsamples the voice signal, the packetengine collects several voice samplesinto a datagrarn. Differentimplementations vary the size of thedatagram to strike a balance betweensignal delay and packet overhead. Adatagrarn consisting of 160 samples, 20ms of the voice signal, is aboutoptimum. The better implementationsallow the user to set the datagram size tosuite the application. The packet enginethen wraps the datagrarn within severalprotocol layers including the real timetransport protocol, RTP, the userdatagrarn protocol, UDP, and IP beforetransmitting it through the networkinterface. RTP is the Internet-standardprotocol for the transport of real-timedata, including audio and video. It isused ,for media-on-demand as well asinteractive services such as Internettelephony. RTP consists of a data and acontrol part. The latter is called RTCP.The data part of RTP is a thin protocolthat provides support timingreconstruction, loss detection, security

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and content identification. With theprotocol overhead, a VOIP call using theG.711 codec requires 70 to 90 kbitis ofbandwidth for current VOIP systems.When using compressing codecs, thebandwidth requirement is between 20and 60 kbitis.

The end-to-end delivery delay of VOIPpackets is critical to the quality of thecall. Through studies and operationalexperience, service providers have foundthat round trip voice delays of more than100 ms are discernible to callers, anddelays of more than 500 ms areunbearable- A 100 ms round trip delaydictates that the end-to-end deliverydelay is only 50 ms. To maintain thequality of the call and assuming a 20 msloading delay for the datagram, then adelay budget of 30 ms is available forrouter queuing and network interfaceemissions delays. This delay budgetimposes a limit of at most two routerhops within a typical network design. Inaddition to overall end-to-end delay,end-to-end delay variance is critical tocall quality. Unlike a data connection,voice is a time sensitive application.Datagrams that arrive late at thedestination are unusable. To compensatefor the delay variance in datagramdelivery, VOIP systems employ a jitterbuffer which also contributes to the end-to-end delay. Discussions of networkdesign for VOIP applications oftenmention network design for Quality ofService, QoS. In this context, QoSusually only refers to the guaranteed

bavailability of a specified bandwidth forthe voice call within the network. While

. this is a necessary condition it is notsufficient for maintaining call quality.The overall network design must also

consider the delay requirements for VOIPapplications.

VOIP Standards

VOIP is a new technology,and aswithany technologyit is still evolving. Thevery earliest systems were completelybased on proprietary implementations.As demand in the systems grew andmore players entered the market, therehas been a shift to developing andimplementing more to standards. Theearliest and still the most widely usedstandard for VOIP call control is basedon the International TelecommunicationsUnion H.320 standard. H.320 is actuallya set of specifications for videoconferencing over a defined, fixedbandwidth infrastructure such as ISDN.IP telephony uses a subset, H.323, of thetotal specification. The H.323specification specifically covers videoconferencing over the IP protocol. Sincetelephony only covers the voicecomponent of teleconferencing some ofthe H.323 protocol specification isirrelevant to telephony. H.323 is astable, established protocol. Importantalso is the fact that H.323 grew out theITU, an international standards body ontelecommunications, essentially thesame organization that developsstandards for the existing publictelephone network. Because it wasinitially developed to support calls overthe switched public network, H.323’scall control functions, which are thesame as for an ISDN call, are morecomplex than what is absolutely requiredfor service over an IT network. Thiscomplexity has led to the developmentof a new set of protocols called theSession Interface Protocol, SIP [Sch].SIP attacks the problem of providingVOIP from a “net-head” perspective.

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The Internet Engineering Task Force,133TF,is the sponsor and developer ofSIP. SIP uses a simplified messagepassing service, similar to electronicmail, for establishing voice calls. Theprotocol is new and still evolving. Sometelecom equipment companies havestarted to develop equipment,telephones, and software utilizing SIPover the last 6 months to a year. We canexpect that these two competing protocolsets will evoIve, and that the twostandards bodies will jockey for positionin defining VOIP standards.

Lucent 7 WE Switch

Market interest is driving Lucent, as wellas other equipment vendors, to developVOW systems. System development isoccurring on small to large carrier classswitches. As part of these developmentsand to keep the switch current, Lucent isadding hardware and features to the5ESS switch to handle VOIP and ATMtelephony and to generally add newfunctionality. Along with these changes,Lucent is renaming the 5ESS switch tobe the 7R/E switch. The 7R/E designdoes not radically depart from that of the5ESS, nor does it necessarily obsoleteany of the 5ESS’S main subsystems.Rather the 7R/E represents anevolutionary path for maintaining thelarge capital investment in a centraloffice class switch.

Lucent has announced new 7R/Eelements to support VOIP, and they areprojecting delivery of these elements inthe second half of calendar year 2001.These elements include a Packet SwitchModule, PSM, a Call Feature Server,CFS, and the Packet InterworkingGateway, IWG. The CFS performs thefunction of a VOIP gatekeeper. It

provides call control functions andimplements telephony features nowperformed by the 5ESS administrativemodule. The CFS processes calls forboth the 5ESS and 7R/E peripherals andadds packet call control to the 5ESS.The IWG performs the role of a VOIPgateway as well as providing an internalbridge for bearer channel traffic betweenthe circuit and packet switched elementsof the 7R/E. The IWG is also capable ofprocessing and handling ATM trafficwhich provides an alternate interface forconnecting to the public network or toanother piivate telephone switch. ThePSM provides the basic fabric forinterconnecting the IWG, the CFS andATM/IP network interfaces. It alsoprovides the fabric for attaching line andtrunk access gateways.

The 7R/E will use the H.323 protocol toimplement VOIP in the CFS. Thecustomer interface is provided throughone or more mechanisms. Also underdevelopment by Lucent is an H.323,network attached telephone. This samephone is intended to work with theAvaya, formerly Lucent, Definity line ofPBXS. They will be customizable toeither of the switches. Note that whileother manufacturers are also producingH.323 phones, these instruments are alllargely proprietary and do not inter-operate. Other customer interfacesinclude standard H.323 soft phonesoftware. The most commonly availablepackage is NetMeeting by Microsoft.Lastly, line access gateways to the 7R/Ewill provide support to terminatestandard telephone instruments. Thesegateways can be remotely placed at thecustomer location and interconnected tothe 7R/E through an IP network.

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This short description of the 7R/Eprovides no more than an overview ofthe direction of the Lucent product.Product delivery is still a year or twoaway before first delivery. As the VOIPtechnology progresses in the standardsbodies and in the market place, one canexpect the 7R/E to evolve.

VOIP At Sandia

There are a number of factors that comeinto play in the decision to deploy VOIPat Sandia. Included among these are thematurity of the technology, cost,reliability, performance, operations,security, and scalability. Also in manycases there are several viabletechnologies that can address a givenproblem or task. VOIP competes withthese alternate technologies, some ofwhich are more mature and tested. VOIPprovides solution sets to addressdifferent telephony applications. Someof these solution sets maybe moreappropriate for use than others. For eachapplication, one has to consider thealternative options on a case by casebasis.

When considering VOIP deployment, itwill rarely involve an all or nothingdecision. What is more likely is that itwill coexist with other technologiesincluding the existing circuit switchedvoice system, wireless, SONETtransport, and others.

Security --

From a security view point Sandia’soperating environment is uniquecompared to many companies. DOE andgovernment orders and the presence ofclassified information and processingsystems oncompletely

site present obstacles tocombining voice and data

traffic. By definition general telephonetraffic is unclassified and has the samesecurity profile as the Internet. In thepublic switched telephone network,PSTN, calls can and do originate andterminate anywhere in the world. AVOIP system at Sandia would reside inthe open environment and likely as anetwork separate from the Sandia OpenNetwork, SON. From an

“implementation perspective, the SandiaRestricted Network, SRN, is the mostsuitable environment for VOLPtraffic.Of all the networks at Sandia, the SRN isthe most pervasive, and it provides adesirable level of protection and threatisolation. However, general deploymentof VOIP on the SRN may require that theSRN assume some of the risks inherentwith interconnection to the publicswitched network.

It should also be noted that telephony byits nature needs to be ubiquitous to makeit the most useful. This drives the needto deploy it into classified computingareas where it may present a securityrisk. While Sandia’s networks cover alarge portion of the population and workspaces, no single network reacheseveryone. This report does not delveinto all of the security ramifications ofVOIP on Sandia’s existing networks otherthan to recognize that security is anissue.

Scalability --

The majority of PBX systems thatcompanigs install are relatively small[SU1][BCR], less than 200 lines. Thishas dictated the initial size of VOIP PBXsystems that vendors have introduced.These systems have been small, tailoredfor a small business or building, andhave been designed for an organization

17

to quickly install a combined voice anddata network. This situation is changing.Vendors are beginning to target largerenterprise and carrier class installations.Systems from Lucent, Nortel, Siemens,and Alcatel fit into this category.

For a VOIP system, scalability mustcover the aspects of system size andcapacity, system distribution, operationsand feature set complexity. System sizeand capacity refer to the configured linesand the call volume. System distributionis the physical location and dispersion ofthe system. Operations and feature setscalability allow the system to offer thefunctionality that customers want in amanner that can be delivered andmaintained.

There have been discussions at Sandiaabout the feasibility of implementing thevoice system with a complete VOIPsolution. By any measure Sandia’s PBX,the 5ESS, is a large installation. AnyVolF PBX that would replace the Sandia5ESS circuit switch functionality wouldneed to accommodate Sandia’s size,distribution, and complexity. Thefollowing addresses some of the basicsystem sizing that would be necessary toimplement such a system. As notedearlier, VOIP, does not represent an all ornothing solution. There may be caseswhere VOIP is applied more selectively.In these instances, the system size wouldneed to accommodate the particularapplication.

Figure 5 and Table 1 show measures ofSandia’s 5ESS usage. Data such as thisprovides the basis for sizing thecomponents of a VOIP system. Thenumber of telephone lines in use, or theline count, provides an indication of the

Line Count 19,840 Active

AverageDaily Call 117,000 CallsCompletions

Maximum 26,000 Calls/HourCall Rate

Table 1 --5ESS Telephone SwitchUsage.

amount of network equipment that isneeded to support telephone services.There is a direct correlation between theline count and the number of hubs,routers, and gateways needed to supportthe service. It also correlates to thenumber of resources needed to performE’ address assignment and configuration.The call completion rates provideindicators of the amount of telephonetraffic that the network will need totransport. It also correlates to thetransaction rate that the gatekeeper willneed to process and the rate of domainname service resolutions that arerequired to support the application.

One can estimate the aggregated trafficthat a Voll? application would generate.The traffic on any one hub, router ornetwork component may vary widelydepending on traffic patterns. Manytimes telephone calls are localized to aphysical region such as a building so thattraffic is also localized. However, onecan not always assume localization andone must expect that a significantamount of the traffic will transverse thenetwork backbone. By referring toFigure 5, the maximum call rate is about

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,

..

TYPICAL WEEK IN THE LIFE OF THE 5ESS SWITCH(total calls handledper hour)

1

25W)0

20000

15000

10000

5000

0

Figure 5-- 5ESS Weekly Traffic Pattern

26,000 calls per hour. A typical call willlast about 5.5 minutes on average. Fromthese statistics we can calculate theaggregate simplex traffic to be190.7Mbits/s. Total traffic would betwice this rate to accommodate the fullduplex nature of a phone call. This rateassumes that the system uses thestandard G.711 codec which has anaverage transport rate of 80 kbitis withavailable VOIP systems. The aggregatetraffic is calculated as follows.

Traflic ~Ute=CR~teEBitRateCkngth,where

cRate, the call rate (in Calls/Hour),

EBi~ate, the bit rate per call (in b/S),

cbmg~h, the call length (in S)

.

Availability/Reliability --

Often times when people talk abouttelephone service they refer to it as a

lifeline service. By this they mean thatthe service is always available and thatpeople rely upon it for emergencycommunications. We have grown toexpect that telephone service is alwaysavailable regardless of external events.To this end commercial equipmentvendors have designed multiple layers ofredundancy into their systems. Serviceproviders, including Sandia, also go togreat lengths to design the telephoneservice so that it is available and that itperforms as expected. In contrast,customers generally do not expect thesame level of service availability fromdata networks and service providers donot attempt to provide the same level ofservice from the onset of the networkdesign- This is not to say that customersdon’t want high levels of serviceavailability, just that they do not expectthat it will happen. This dissimilarity inservice levels presents a dilemma to

19

designers in trying to provide telephonyservices over a data network service.

The deployment of VOIP services onSandia data networks will require thatthe data networks are specificallydesigned and operated for availability.Some aspects of the data network thatmay introduce obstacles to making thesystem available include equipmentreliability, configuration management,complexity, system design, servicematurity, and customer expectations.

Telephone services provided throughdigital switches such as the 5ESSrepresent a very optimized and verticalapplication. The 5ESS is designed toexecute a single application in aparticular manner -- the delivery of voicecalls and features through circuitswitched channels. This designminimizes system complexity and makesit easier to manage, and correspondinglymore reliable. By contrast the datanetworks that Sandia implements aremore complex and serve a number ofapplications. This complexity does notpreclude the system from functioning atexpected service levels, but it makes itharder to operate them so that they doperform. The data networks transportvarious protocols for variousapplications that require different systemservices. Applications require thatseveral key services all functionsimultaneous] y for the application to n.m.In most data network designs there areawide variety of routing engines, hubs,and interfaces. VOIP layers telephonyservices on top of data network services;the components of both of these serviceshave to perform at a very high level toachieve the desired overall systemavailability. Minimization of data

network system complexity is integral toachieving the desired VOIP serviceavailability.

A telephony system, whether VOIP orotherwise, is a collection of subsystems,and the system availability is directlyrelated to the availability of thesubsystems. The availability of the5ESS switch is specified at 99.9999%, orout of service for 31.53 seconds per year.However, the availability of anindividual phone line to a customer isless than this amount because of failuresin cable, power, or other factors. Tomeet the expected system availability,the system designer must design theoverall system with high availabilitysubsystems and with subsystemsredundancy. S andia’s data networks arecurrently not designed to this criteria.Equipment such as routers and hubs donot have active redundant boards orcomponents. One area of focus in thedata network is design for loss ofcommercial power. The network is notspecifically designed to survive acommercial power outage or theintentional disabling of power tobuildings at specified times. For Voll? tobe successful, the data network and anyVOIP specific services must be designedfrom the beginning for systemavailabilityy.

Customer expectations play a large rolein data network availability.Traditionally, customers have notdemanded the same level of availabilityfrom data networks and services as theyhave from the telephone network. As aresult, operational and design practiceshave emerged that hamper systemavailability. It is not uncommon, to seecustomers or services providers at

20

Sandia make data system changes duringperiods when it can be reasonablyexpected to affect service or to makeimplementation changes that are likely todegrade availability. When data serviceoutages do occur, the perceived cost ofthe outage is not placed as high as theperceived cost of telephone networkoutages. Data network services are stillevolving more quickly than telephonyservices. As a result, customer demandfor faster or different network interfacesand the demand for the new featureshave shifted the service deliveryemphasis to performance at the expenseof availability. These differences are notinherently wrong, however they present aproblem in trying to provide an expectedlevel of telephony service through thedata network.

Recommendations

One condition that arises in deciding todeploy a VOIP telephone system atSandia, is that we are trying to comparea very mature system with well knownfunctionality and costs to one that ismuch less so. VOIP involves a rapidlyevolving set of products, with emergingfunctionality, and with less wellunderstood cost components. To datewe have not found documentationregarding a large, distributed enterpriselike Sandia entirely transitioning toVOIP. However, companies havesuccessfully deployed VOIP for specificapplications where VOIP providedadvantage.

We have repeatable field data thatdemonstrates that the 5ESS and our datanetworks offer two distinctly differentlevels of availability. Additionalprobing of other aspects of availabilitysuch as the number of simultaneously

out-of-service devices or ports needs tobe compared. We designed thetelephone system to a specification thatputs a limit on that number, but we donot in “general design our data networksas such. We regularly design the datanetworks to fill all available ports andlimit the total number of chassis in thefield in an effort to minimize thecostiport. We would need to redesignour data networks to accommodatereducing the breadth of outages that asingle component failure would induce.To do so would most certainly affect thecost and management of our datanetwork, potentially to the point ofnegating any cost savings of migratingthe voice and data services together.

VOIP is currently receiving a lot ofattention in the marketplace which is onedriver for this discussion. Whenconsidering changes to Sandia’stelephone system with respect to VOIP,the discussion should not be centered onimplementing a system that is entirely orlargely built using packet switchingtechnology as opposed to the currentcircuit switched implementation.Rather, a coexistence of the twotechnologies is more likely. Voll? is stillevolving with respect to standards andproduct development and at this time isimmature.

There are specific operational instanceswhere Voll? has made a difference toother companies. In instances whereSandia’s situation” is similar, VOIP couldpossibly provide cost and operationalbenefits. Organizations that have had tosupport different switching systems atmultiple locations have been able toreduce cost and operating effort bydeploying VOW. At Sandia we have a

21

similar situation in the way we provideservices to offsite locations such as theResearch Park complex, the BDMbuilding, and Sandia’s Carlsbad office, aswell as other potential locations. In eachof these instances, we extend both datanetwork services and services from the5ESS. At Carlsbad we also have tosupport a different PBX; support thatcould be absorbed into a central switch.The other major area where companieshave deployed VOIP is in call centerapplications. In these settings the callcenter operators need close integrationbetween voice and data services andhave found that the delivery of voicethrough the computer to improve theiroperations. As VOIP technologyevolves, its range of practicalapplicability to Sandia may increase.

When trying to evaluate cost advantagesto using VOIP, one must be careful tooptimize for overall system costs and notjust subsystem cost benefits. It has beenproposed that VOIJ?could result in costsavings in operating and maintainingSandia’s outside cable plant and ductsystem. Sandia’s outside cable plant ismore than 40 years old in somelocations, and it needs to be replaced[ARC]. When considering up frontcapital expenditures, VOIP appears to beless expensive. However, this does notpresent a view of the entire life cyclecost. Voice transport via VoIP is muchmore complex than that over coppercable, and it is reasonable to expect thatit will be more expensive to operate.There is also a wide disparity in the lifespan of the two systems which will drivereplacement costs in the future.

It is possible to integrate voice and datanetwork services without actually

integrating the underlying networks. Asan example of this type of integration,consider the WEB Dialing application.With this service, a customer is able touse browser software on his or hernetwork-connected computer to locatesomeone’s phone number from anelectronic directory. The customer isthen able to place a phone call to thatperson through the selection of ahyperlink tied to that phone number.The customer benefits from astreamlined process of locating a phonenumber and then placing a call to thatnumber. Other examples of functionalintegration include data network basedfacsimile transfer, voicemail basedfacsimile receipt, data network deliveryand handling of voice. Each of theseapplications makes use of synergisticfunctions of the voice and data networks.The strength of each network isleveraged to provide the customer aservice that is more functional and easierto use than what could be provided byeach network alone. Sandia shouldcontinue to look for and implement thesesynergistic opportunities.

Sandia’s aging inter-building cablesystem [ARC] and its Move, Add,Change, MAC, work load are twosignificant cost areas. While VOIP mayprovide one method for reducing thesecosts, other technology alternatives arealso available. In particukr SONETdistribution coupled with buildinglocated, subscriber line distributionequipment is a well known and maturetechnology to address inter-buildingcabling. Wireless technology alsopresents a viable alternative to reducecable, duct system and MAC costs.Wireless also enables user mobility.While this paper predominately looks at

22

*

.

VOIP, VOIP as well as other availabletechnologies should be considered.

The following initiatives should beconsidered to leverage the existinginfrastructures while taking advantage ofevolving technologies.

. Continue to integrate best of bothvoice and data work processes intosynergistic systems.

. Continue to consolidate operationssuch as Customer ServiceRepresentatives, Trouble Desk, andother processes to supportmoves/adds/changes.

● Continue funding VOIP initiatives toremain abreast of the technology andits direction. At the same timeconsider and fund othercomplementary technologies such aswireless.

● Monitor closely the evolution of. Lucent’s 7R/E switch

. Continue to monitor the marketplacefor case studies or product hunchesthat suite large, physically diverseenterprises like Sandia.

. When making changes or additionsto the data network, design inavailability and performance levelsto accommodate VOIP.

. Support long term infrastructureimprovements such as the ExteriorCommunications InfrastructureModernization to insure that nomatter which path current technologytakes, the inside and outside plantinfrastructure remains flexible andviable enough to provide whatevertelecommunication technologyemerges.

Summary

Technological innovations and industrydevelopments in telecommunicationshave recently generated substantialinterest in combining voice, video, anddata networks. There are several driversfor wanting to combine these networks.They are expected lower cost structureand increased system efficiencies,regulatory changes, the development andmaturing of underlying technologies thatfacilitates service convergence, and thepromise of new customer applicationsthat would not otherwise be possible.

In considering voice and data networkintegration there are a number of systemrequirements that the telephone systemmust address. Requirements derive fromservice provider and end customerconcerns.

From an end customer perspective, thetelephone system must promote voicecommunications, work as expected, meetthe reliability expectations, and newservices and service changes must bedelivered within a certain time. Costcontainment or reduction if possible is astrong driver of the telephone system andits implementation. However, it is notthe only or necessarily the leadingrequirement. Rather, other customerrequirements need to be met at anaffordable price. In many respects, costto provide service is a service providerrequirement since the end customer is farremoved from the funding process inSandia’s current funding structure. Otherservice provider requirements includecomplexity reduction, flexibility toprovide services when and where theyare needed both on and off campus, andmaintenance of interconnectivity andcompatibility with the public network. A

23

growing requirement is to meet themobility and flexibility needs of ourcustomers.

It is possible to integrate voice and datanetwork services without actuallyintegrating the underlying networks.Examples of this type of integrationinclude Web dialing, data network faxdelivery, unified mail messaging andinteractive voice response services.Integration can also occur at theoperational level. Each network requires”engineering support, installation andmaintenance crews, procedures andprocesses for delivering services,documentation systems to trackcustomer orders and the state of thesystem, and mechanisms for servicerestoration in the event of an outage.

VOIP, or the transport of voicecommunications over the InternetProtocol, manifests itself in a few basicapplications. The applications includeswitch to switch trunking, network basedprivate branch exchanges call centerapplications, and mobile telephony.Voll? as it has arisen in the market takestwo forms. PBX to PBX gateways andnetwork based “PBXS.” VOIP is anevolving technology. It is based on bothproprietary and international standardsbody specifications. Specifications thatare still in flux. VOIP also makesspecific demands on the underlyingnetwork to maintain service levels.There are a number of factors that comeinto play in the decision to deploy VOII?at Sandia. Included among these are thematurity of the technology, cost,reliability, performance, operations,security, and scalability. Also in manycases there are several viable

technologies that can address a givenproblem or task.

One condition that arises in deciding todeploy a VOIP telephone system atSandia, is that we are trying to comparea very mature system with well knownfunctionality and costs to one that ismuch less so. VOIP involves a rapidlyevolving set of products, with emergingfunctionality, and with less wellunderstood cost components. To datewe have not found documentationregarding a large, distributed enterpriselike Sandia entirely transitioning toVOIP. However, companies havesuccessfully deployed VOIP for specificapplications where VolP providedadvantage. Sandia can leverage it voiceand data networks by continuing to

integrate the best voice and data workprocesses and operations, investigatingVOIP products such as the Lucent 71UE,making data network changes tofacilitate VOLP, and investing in theinfrastructure.

24

,

.

d

.s

References

[And]

[ARC]

[BCR]

[Cas]

[Dmm]

[Duk]

[Len]

[Min]

[Ren]

Sch]

Sul]

Gary L. Andresen, “Telecom Servers Lend Muscle to Flabby PBXS,” CTI News,pg. 8, February 9, 1999.

“Justification for Critical Decision 1: Sandia National Laboratories ExteriorCommunications Infrastructure Modernization,” Architectural ResearchConsultants, Inc., January 27, 1999.

Business Communications Review, “Proceedings of the PBX2000 9th AnnualConference on Enterprise Voice Communications,” February 8-11, 1999,Washington DC.

Peter Cassidy, “Talk is Cheap Over the Internet,” Information Week, pp. 174-178, November 16, 1998.

Arielle Dmmett, “Tentative Steps For Convergence,” Business CommunicationsReview, Voice 2000 Supplement, pp 24-30, February, 2000.

Jeremy Duke, “Data & Voice Court, but Still No Wedding,” BusinessCommunications Review, Voice 2000 Supplement, pp 4-7, February, 2000.

Grant Lenahan, “Next Generation Networks A Practical View of NetworkEvolution,” NGN Solutions, Bellcore (Telcordia), 1999.

Hilary Mine, “The Evolution of Internet Telephony,” Probe Research Inc. whitepaper, September 1998.

John Rendleman, “Cisco to Unwrap IP PBX,” PC Week, pg. 8, March 1, 1999.

Henning G. Schulzrinne and Jonathan D. Rosenberg, “The Seesion InitiationProtocol: Providing Advanced Telephony Services Across the Internet,” BellLabs Technical .Toumal, pp 144-160, October-December, 1998.

Allan Sulkin, “On-Going Evolution of IP-PBX Systems,” BusinessCommunications Review, Voice 2000 Supplement, pp 14-22, May, 2000.

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Distribution

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P. J. Vandevender, 9010 2 0899 Technical Library, 9616M. O. Vahle, 9300 2 9018 Central TechnicalF. Mason, 9302 Files, 8945-1W. D. Swartz, 9313 1 0612 Review & ApprovalC. D. Brown, 9321 Desk, 9612 for DOWOSTIL. Stans, 9316J.P.Brenkosh,9316L. D. Dean, 9316J. M. Ekh-idge, 9316M. J. Ernest, 9316S.A.Gossage,9316R. L. Hartley, 9316T. C. Hu, 9316J. A. Hudson, 9316L. G. Martinez, 9316M. M. Miller, 9316J. H. Naegle, 9316L. G. Pierson, 9316T. J. Pratt, 9316J. A. Schutt, 9316T. D. Tarrnan, 9316L.F.Tolendino,9314E.L.Witzke,9316J. P. Noe, 9318G.Connor,9310M.R.Sjulin,9314R. L. Adams, 9314D. B. BatemanL-D. Byers,9314M.D. Gomez, 9314J. H. Maestas, 9314P. Manke, 9314P. D. Rocchio, 9314G.F.Rudolfo,9314B.C. Whittet, 9314R. M. Cahoon,9311K. E. Washington, 8900S. C. Gray, 8930L. A. Brown, 8930

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