Advanced Traffic Routing as Part of the USA Intelligent Telecommunications Network

Transcription

1 Advanced Traffic Rouing as Par of he USA Inelligen Telecommunicaions Nework Edmund P. GOULD Bell Communicaions Research 435 Souh Sree Morrisown, New Jersey The USA Telecommunicaions Nework is evolving oward an Inelligen Nework uilizing he Inegraed Services Digial Nework (ISDN) for access flexibiliy and conrol and Common Channel Signaling (CCS) for signaling flexibiliy. Modern voice, daa and image elecommunicaion services, including hose requiring broadband capabiliies, will be provided by his oally inegraed and flexible nework. Advanced mehods for rouing calls ransimg he inegraed nework also become pracical due o new Operaions Sysems conceps combined wih he key elemens of he Inelligen Nework archiecure. These more responsive and conrollable rouing mehods provide neworking efficiencies and capabiliies ha furher enhance he value of he Inelligen Nework. This paper oulines he overall srucure of he presen USA Nework and is evoluion ino an Inelligen Nework ha makes use of advanced raffic rouing echniques. Forces Driving USA Nework Evoluion Three basic forces are driving he evoluion of he USA Telecommunicaions Nework. Firs, increasing cusomer demand for new services capabiliies in he marke place requires increasingly efficien informaion ransfer. Business cusomers wish o use voice, daa, image and video services o reduce coss and improve operaional procedures, and o enhance heir individual compeiive advanage. Residence cusomers wan qualiy voice communicaion bu also increasingly desire daa and image services for enerainmen as well as " home offices". The demand for home enerainmen will drive he developmen of video services o he home. These services require he ype of informaion ransfer provided wih a Nework ha uses he laes broadband echnologies. The second force driving nework evoluion is he rapid advancemen being made in he deploymen of a oally digial end-o-end nework. The availabiliy of Very Large Scale Inegraion (VLSI) echnology and opical fib er have brough an end-o-end digial nework closer o realiy han was hough possible only a few years ago. This new digially based echnology along wih advancemens in sofware generaion provides he impeus for a rapid evoluion o an Inelligen USA Nework. The hird force is he effec of governmen policies on he srucure of he USA Nework. The impac of legal and regulaory policies have been so significan ha i is useful o highligh he curren nework srucure. Srucure of he USA Telecommunicaions Nework The curren USA Nework srucure including he many places requiring sandards is shown in Figure 1. A call ransiing muliple exchanges (called "LA T As" in he USA) is placed by a cusomer (end user), using Cusomer Premises Equipmen (CPE). Access o he "long disance" porion of he Nework is provided by a Local Exchange Carrier (LEC). A call is ranspored by an Inerexchange (iner "LATA") Carrier (IXC) o he erminaing exchange where he Local Exchange Carrier (LEC) complees he call o a erminaing end user uilizing CPE. Enhanced Service Providers (ESP) are hird pary vendors who provide informaion services o end users in conjuncion wih basic nework feaures provided by a LEC. No only are sandards required wihin he separae eniies composing he oal Nework because of manufacuring and physical inerfaces, 6.2iA.2.1

2 CPE MFR = CUSTOMER PREMISE EQUIPMENT MANUFACTURER LEC = LOCAL EXCHANGE CARRIER IXC = INTEREXCHANGE CARRIER ESP = ENHANCED SERVICE PROVIDER Figure 1_ END USER I INTERFACE STANDARDS SERVICE, EQUIPMENT, CONFIGURATION STANDARDS END-TO-END PERFORMANCE STANDARDS Srucure of he 1987 USA Telecommunicaions Nework 1 END USER bu he boundaries beween he eniies also require inerface sandards. Responsibiliy for service performance is divided when his many nework eniies are involved in providing end-o-end service. To minimize problems clear indusry sandards defining inerfaces beween he eniies, and he performance required from each par of he end-o-end connecion are required. Of course, in realiy, each porion of he Nework in Figure 1 is shown raher simplisically. There are compeiors poenially involved in several of he six Nework eniies shown -- a reason for increasing concern wihin he USA for he developmen of adequae Nework sandards. The growing commonaliy of ineress and concerns of he worldwide business communiy ha requires inerconnecion among naional Neworks and wih inernaional Neworks, mandaes he USA ineres and paricipaion in CCIrr direced sandards effors. Along wih his Nework srucure has come inense ineres in he USA in providing an Open Nework Archiecure o allow full inerconnecabiliy of various manufacurers' producs. This process is faciliaed by basing appropriae sandards on he Open Sysem Inerconnecion (OSI) 7-layer proocols. Trends in he USA Telecommunicaions Nework Due o Technology Several imporan rends in echnology, generally available o many vendors, make evoluion o an Inelligen Nework feasible. Semiconducor echnology, fiber opics, and digial echnologies for boh swiching and ransmission applicaions are conribuors. However, sofware advances are becoming increasingly imporan. In paricular, Powerful Daabase Technologies. New daabase design, daabase languages, and compuing echnology now make he ineracion of daabase funcions wih real-ime nework operaions feasible. Flexible Sofware Conrol of Nework Elemens. Combining compuing power wih recen advances in daabase echnologies allows for he design of Inelligen Nework elemens wih sofware conrol. < These advanages in sofware echnology permi he evoluion of he USA Nework o an Inelligen Nework uilizing all digial echnology wih sofware conrolled daabases and nework elemens. Relaionship of Inelligen Nework Evoluion and Operaion Sysems A key poin when considering he advancemens in echnologies is he opporuniy o use hese same echnologies o consruc inelligen Operaions Sysems o plan, adminiser and operae he Nework. The funcionaliy of Operaions Sysems, nework elemens and adjunc equipmen are becoming more similar. The USA Nework is increasingly moving owards becoming a processor of informaion uilizing sofware inelligence and nework daabases for conrol. A he same ime, operaions and planning processes are increasingly uilizing informaion from he Inelligen Nework elemens and sofware based Operaions Sysems. Evenually, as eiher he Nework end user, he Nework Adminisraor, or inelligen Operaions Sysems provide conrol and rearrangeabijiy of available capaciy, here will be a srong linkage among nework elemens, nework elemen planning and Operaions Sysems advances. 6.2iA.2.2

3 Figure 2 shows he fuure relaionship of he Nework iself and nework Operaions Sysems in he Inelligen Nework archiecure. Inelligen Nework elemens ~re consanly measuring and monioring hemselves wih resuls sen o boh a Nework Conroller and nework Operaions Sysems. Nework Conrollers are responsible for evaluaing near real ime nework demands (based on measuremens), comparing hem o available runk and faciliy capaciy, and rerouing raffic or rearranging runking and faciliy capaciies o achieve he bes possible hroughpu. Nework adjusmens made by he Conroller are sored in Operaions Sysems' daabases. A a laer ime, a planning sysem, under planner conrol, can recommend new nework archiecures and major capaciy augmens. Viewed as a whole, one sees ha he Nework Conroller and he Operaions Sysems ac as inelligen peripherals o he Nework iself, essenially making hem par. of he Nework. Similarly, he Nework is becoming a source of daa for he planning processes. Thus, he Nework, Operaions Sysems, and nework planning are becoming inegraed and, perhaps, will be indisinguishable in he fuure. The nex secion illusraes he full power of he Inelligen Nework archiecure wih is use of a Inelligen Nework Conroller o provide new services. MAJOR NETWORK CHANGES COMMUNICATIONS NETWORK MEASUREMENTS. SERVICE MANAGEMENT SYSTEM (SMS) ~ - - POINT (j~ g5~+~'cil (SCP) COMMON CHANNEL SIGNALlNG (CCS) Figure 2. The Inelligen Nework and Operaions Sysems Figure 3. Inelligen Nework Service Concep The Iniial Inelligen Nework Archiecure A simplified block diagram of he essenial building blocks in he iniial Inelligen Nework concep are shown in Figure 3. Sofware conrolled digial swiching sysems called Service Swiching Poins (SSPs) are inerconneced by a high speed Common Channel Signaling (CCS) nework o cenralized daabases called Service Conrol Poins (SCPs) which assis he call processing funcion using informaion gained by special end user dialing sequences. Sophisicaed Operaions Sysems like he Service Managemen Sysem (SMS), shown in Figure 3, load and mainain he daa in he SCP. A second sysem, no shown in Figure 3, is called he Signaling Sysem Engineering and Adminisraion Sysem (SEAS). SEAS mainains and adminisers he signaling nework componens. The bes way o undersand he naure of he Inelligen Nework archiecure is by describing an example of how a service, billing o he called pary versus he calling pary C" 800 Service" in he USA), is handled. When a call is dialed o an 800 prefixed number, he local exchange recognizes he 800 number and roues he call o a designaed SSP, which has special sof\\'are o process such calls. When an SSP idenifies a call as an 800 call, i suspends he call processing in order o gain furher informaion for he call reamen. This informaion resides in an SCP daabase. To access his informaion, he SSP sends a message o he SCP via he CCS signaling nework. The signaling nework uses specialized packe swiches, called Signal Transfer Poins (STPs). In his 800 Service example, he message from he SSP o he SCP conains he dialed 800 number as well as informaion abou he calling pary. Based on he incoming daa, service logic in he SCP ranslaes he received 800 number ino a sandard elephone number and reurns his elephone 6.2iA.2.3

4 number, ogeher wih a rouing insrucion, o he Service Swiching Poin. The SSP, upon receiving he rouing insrucion from he SCP, is able o roue he call o he desired desinaion. In general, he calls in he Inelligen Nework which require special processing mus reach an SSP. When' he SSP recognizes ha i alone canno process he call furher, i inerrups call processing and launches a daa query over he CCS signaling nework o an SCP. Such a query can include all he informaion regarding he calling and called paries ha he SSP has available. The SCP, which handles many SSPs a he same ime, provides he SSPs wih needed call progress daa. The daa are no only service specific, bu also can be cusomer specific. For example, he cusomer record in he SCP can opionally include rouing insrucions which vary by ime of day, by day of week or by he originaing caller's locaion. If he informaion received by he SCP is no sufficien o define furher call processing, he SCP can also send addiional commands o he SSP which hen in urn may require furher inpu by he cusomer. In he Inelligen Nework, a single SCP can be used o handle one applicaion for a large geographic area, or, i can be used o handle muliple applicaions. The Inelligen ISDN Nework Archiecure In Figure 3, access o he Inelligen Nework is indicaed as a cloud. In he evolving Nework his cloud will be implemened hrough he ISDN archiecure hus creaing an Inelligen ISDN Nework. Figure 4 indicaes how, ISDN conceps are combined wih he Inelligen Nework. ISDN provides for voice/daa service inegraion, iniially in nework access, over digial loop faciliies. The ISDN access archiecure allows for shared or dedicaed access, new nework services, variable bandwidh calling, and user-o-user signaling. Alhough early implemenaions reain separae packe, circui, channel, and signaling ranspor neworks, evenually a more unified bandwidh swiching and ranspor nework will probably emerge. Combining ISDN conceps for inegraed access wih he Inelligen Nework and Operaions Sysems resuls in a powerful archiecure design. Figure 4 shows he posiioning of he SCP as a Nework Conroller in he Inelligen Nework and he merging of he Nework, Nework Conrollers, and Operaions Sysems. FUTURE NETWORK - ISDNIIN SW -----f Figure 4. The Inelligen ISDN Archiecure The Fuure Evoluion of he Inelligen Nework A key Inelligen Nework concep is he ineracion of convenional call processing in he SSP for cerain ypes of calls wih Service Logic Programs and daa bases which can be eiher in he swich or in a cenralized SCP. This allows flexibiliy in service design by providing for deploymen and modificaion of services hrough changes in he cenralized service logic programs conained in he SCP sofware raher han in he nework swiching elemen iself. As he service demand grows, call 6.2iA.2.4

5 ITe 12 Torino, June 1988 processing can be migraed back o he swich. Recognizing ha his concep is a powerful ool for cusomizing services and for acceleraing heir universal deploymen, he designers of he Inelligen Nework are now exending he concep o realize even more advanages. The naural evoluion in he fuure Inelligen Nework is he concep of modularizing call processing capabiliies in he swich (SSP) and Service Logic Programs in he swich or SCP. This evoluion is based on he premise ha services can be broken down ino basic componens. A comprehensive se of hese basic componens can be defined for he SSP which could hen be used o consruc many differen services. If he se were complee enough, hen newly conceived services could be implemened by only wriing new sofware for he SCP. This sofware could hen provide he proper selecion and sequencing of he basic componens o form he new service. The design of hese basic componens, which in he Sandards arena are known as Funcional Componens (FCs), forms he basis for he evoluion of he Inelligen Nework. Through a well defined se of FCs, nework sofware no longer needs o be service specific. Raher, a new service could share nework elemens and be defined insead hrough linking or "siching" ogeher he appropriae FCs. Such an archiecure, if successfully designed, would minimize he economic risk of rying new services conceps and would speed he universal deploymen of any paricular new service. Because he Inelligen Nework archiecure provides a considerable amoun of flexibiliy o creae new services, an inerface o a hos of service providers, who wish o provide value added services in combinaion wih basic nework service capabiliies, will provide a greaer selecion of services offerings.. Advanced Rouing Techniques Uilizing he Inelligen Nework The primary moivaion for evolving o an Inelligen Nework is mos ofen saed as he abiliy o provide new services quickly o enhance he revenues of he service provider. However, hese same echnologies advances ha allow he implemenaion of an Inelligen Nework for new services also allow advances in how calls are roued in he Nework. HIERARCHICAL NETWORK TRUNK GROUP MEASUREMENTS TRUNK GROUP REROUTES 5 MINUTE " NETWORK MANAGEMENT I~ FACILITY CAPACITY AUGMENTS DEMAND SERVICING WEEKLY FACILITY PLANS ROUTING CHANGES SWITCH PLANS NETWORK PLANNING OPERA nons SYSTEMS Figure 5. Hierarchical Traffic Rouing and Is Operaions Suppor Figure 5 shows a block diagram of a ypical hierarchical nework and is relaionship o he operaions and capaciy planning processes. Nework rouing is planned monhs o a year in advance, based on forecass of sysemaic raffic paerns. To respond o non-forecas demands, Nework Managemen can emporarily re-roue a runk group's raffic based on measuremens aken every five minues. In addiion, faciliy capaciy can be changed based on semi-annual forecass and on measuremens ha are aken every week. Because of he relaively slow analysis and implemenaion of rouing changes, he presen nework rouing does no ake much advanage of he ime variaion of loads wihin seconds, hours, days, seasons, ec. In addiion, hierarchical 6.2iA.2.5

6 ITe 12 Torino, June 1988 rouing resricions (and infrequen rouing changes) do no allow nework raffic demands o access all available nework capaciy. Advanced rouing echniques allow he nework o respond quickiy in a flexible, efficien way o nework demands in ha hey provide he capabiliy o change faciliy capaciy and raffic roues more dynamically. In he fuure Inelligen Nework, his could be ulimaely on a call by call basis. The main benefi ha advanced rouing echniques offer is higher hrough-pu, i.e., he abiliy o roue more calls for a given nework invesmen -- essenially a cos reducion. These capabiliies allow he rouing o ake advanage of he non-coincidence of raffic loads. They also allow nework demands o access more of he nework capaciy boh because of heir responsiveness and because he raffic rouing echniques are no resriced o a hierarchical model. In addiion o higher hrough-pu, hey offer oher significan poenial benefis of greaer robusness o forecas error, more efficien nework raffic managemen, more flexible grade of service, higher nework survivabiliy, and new nework managemen service opporuniies. Advanced rouing echniques can be accomplished by adding rouing inelligence o planned advancemens in he Inelligen Nework. Rouing inelligence in an advanced rouing conrol poin is analogous and. complemenary o he service logic programs in a Service Conrol Poin (SCP) in he Inelligen Nework archiecure. Advanced rouing conceps will more closely couple he nework and is operaions suppor by moving some of he responsibiliies of nework planning and adminisraion closer o he nework iself.. They build on planned advancemens in he areas of raffic measuremens, swiching sysem memory adminisraion, nework raffic managemen and nework planning. NON HIERARCHICAL NETWORK POINT TO POINT AND TRUNK GROUP MEASUREMENTS PRE.PLANNNED ROUTING TABLE A HOUR 1 A D A D 1 A C-D A B D 1 A B D POINT TO POINT AND TRUNK GROUP REROUTES , 5 MINUTE " NETWORK MANAGEMENT I~ I ROUTING CHANGES AND FACILITY CAPACITY WEEKLY AUGMENTS r= ~ -:-:-l.-":':':=~-j----j DEMAND SERVICING FACILITY PLANS ROUTING CHANGES SWITCH PLANS , NETWORK PLANNING Figure 6. Non-Hierarchical Rouing A concepual diagram of an exlsmg advanced rouing echnique, Dynamic Non Hierarchical Rouing, deployed by AT &T in he USA is shown in Figure 6. Wih his arrangemen he preplanned rouing changes are insiued o accoun for sysemaic variaions in raffic poin-o-poin demand, e.g., seasonal, ime of day, ec. Sophisicaed Nework Managemen conrols are sill used o adjus he raffic rouing o maximize call compleions during significan overloads, e.g., disasers, nework failures. This advanced rouing echnique alhough no insananeously responsive o he saus of he Nework is a major advancemen in he applicaion of sofware echnology in how calls are roued. New sophisicaed Operaions Sysems for forecasing, nework measuremen processing and Nework Managemen along wih a reliable daa communicaions nework and sofware conrolled swiching sysems are all required o implemen his advanced rouing echnique. The successful implemenaion of Non Hierarchical Rouing encourages houghs abou evolving he USA nework oward a fully responsive raffic rouing capabiliy. The similariy of he archiecures 6.2iA.2.6

7 needed for he Inelligen Nework and ha needed for his advanced rouing echnique is shown in Figure 7. Advanced raffic rouing is based on echnology in advanced swiches, CCS Signaling and a Rouing Conroller. Advanced raffic rouing can be accomplished by having he swiches send runk busy/idle saus o a Rouing Conroller, and he Rouing Conroller send new rouing informaion o swiches. The logical funcion of he Rouing Conroller could be implemened in cenral compuers ha communicae wih he swiches, or could be implemened in a disribued fashion. Thus, call by call responsiveness using advanced rouing echniques shares a. srong synergy wih he fuure Inelligen Nework. For example, upon he arrival of an Inelligen Nework call, he Inelligen Nework could be queried for boh he service feaures and he rouing pah of he call. One imporan advanage of his rouing echnique is ha he demand servicing funcion of oday's hierarchical nework may no longer be needed since he nework call-by-call rouing capabiliy compensaes for runk shorages. NON-HIERARCHICAL NETWORK I NETWORK STATUS ROUTING CONTROL SERVICE CONTROL MINUTES OR CALL-8Y-CAL REROUTES NETWORK MANAGEMENT NETWORK PLANNING Figure 7. Advanced Traffic Rouing - A Capabiliy o Change Roues Based on Sae of, Nework Challenges for he Fuure The echnologies for he elecommunicaions Nework of he fuure are largely available oday. The USA Telecommunicaions Nework is evolving o be all digial paving he way for ISDN and Inelligen Nework implemenaion. The Inelligen Nework archiecure is he foundaion on which a hos of Informaion Age services can be suppored. In he USA, he challenge will be o inerconnec he neworks of he Local Exchange Carriers wih he Inerexchange Carriers o creae a funcioning end-o-end Inelligen Nework. This Inelligen ISDN Nework will flrs appear in islands wih inerfacing poins beween he various nework providers. This will require he creaion and close adherence o inerface sandards o allow he complee inerconnecion of all nework providers. Likewise, advanced rouing echniques will appear iniially in only pars of an end-o-end connecion. The conceps described in his paper provides a basic foundaion on which many poenial new services using advanced rouing echniques can be implemened o allow he mos efficien use of he Inelligen Nework elemens. Implemenaion of advanced rouing echniques will suppor he goals of he Inelligen Nework by providing increased flexibiliy and nework responsiveness. These advanced rouing echniques requires exensive work o design he Inelligen Nework and Operaions Sysems ha allow for varied raffic rouing for each call. The poenial o use he same echnology for Inelligen Nework elemens and Operaions Sysems will provide a join evoluion o an Inelligen Nework wih an advanced rouing capabiliy. 6.2iA.2.7