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Mohsen Guizani
Ammar R a p s
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Mohammed A tiquzzaman
T
he growth in Internet Protocol (TI’)-bascd services in Ihc last few years has been cxplnsive. It is projcctcd that this
market will cotitinue to grow at an even higher rale for scvcral years to come. IF-basctl scivices allow ctrrricrs to provide differciitiated services tuncd tn specific scgincnts, and customers. This inclndcs virtual privatc nctwork (VPN) ;ind LAN servicc, electronic commerce (e-commerce), and of course lntcrnct telephony, Tablc 1 shows an cxatnple of thc fot’ccnst data for thc total global 1P tclepliony scrvicc market. Whilc thcre are inoi’c tlian 100 years of experience i n designing, operating, and managing traditional circuitswitched networks, limited data is available abou[ IP-based nctworks. l h o siiccess of Internct tclcphony i i s wcll as other IP serviccs depends primarily on a clear uriderstanding of the overall technology mil servicc reqiiiremcnts. As Internet technology cvolves, companics have many qucstions t o answer in ordcr to carry voicc over the Internet -or voice ovcr IF (VoIP) 2 successhilly. These questions include thc economic advmtagcs to both servicc providers and cnd users, the set of new serviccs, and the quality of service (QoS) reqiiircments. Soinc sce voice ovcr the Internet a s bcing nearly frcc atid would like to take atlvantagc of this apparciit lionnnza without having to worry ahout owning their own nctworks. Anotlicr advantage would he the ability to support “off-nct” voice wpplications, Yct anothcr is to allow a company to reach voicc iisers outside of its own administrative boundarics. However. the ulti.
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inate benefits may be duc more to voicc cotnpression at the source tliaii from the transport vehicle itsclf (the Interiict). We rcccivcd m m y intcrcstitig articlcs for tbis spcciiil issue. We have sdcctcd only eight articles that provide answcrs to a ’ few of the qiicstions iii thc field of littcrnct telephuny. These articles cover R spcctriim of topics that rmgc from IP managcmcnt atid QoS tu the slandsrds and dcsign ofroicc OVCL’ IP components. Tlic first article i n this issue, by Rages and Sagc, discusscs an integratcd nianagemcnt architecturc for IP-based nelworks, illustrating the funclioiis needed to support the chaflengcs uf inanaging VoIP services. Unlike dnta-transfer-baser1 applications, w i c c transport across an 1P-based infrastructure dcinantls low latcncy and jittcr. Not only will the performancc thrcsliold triggers bc different, thc servicing of VoIP packets rvoiild be done based on a priorily sclicduling sclicmc. The particiilnr sclicmc used and thc type of traffic woitld rlctcroiine the correctivc mcasures nccdcd to fix a problcm. Examplcs of priority scheduling systcms i t ~ i ild c cxpedited furwarditig as dcfined in the diffcrentiatcrl scrvices (DiffSciv) framework, atid Priority Queuing with Class-Based Weighted Fair Qucuiiig. liitcgrated inanagcment architccture helps mcdiate lhcsc differencos, limiting thc cxposure of thc differenccs to matiagemciit opcrators and cnd cnstomers. The arliclc dcscrihes Ihc fivc WAYS fiinctiorial arcas: fault managcmcrit, configuration managenient, accounting inanagcinent, pcrformance nii~uagc~net~l, aiid secitrity management.It alsrr discusses sctvice resloration, traffic enginecring, data collcctioti, servicc activation, and network plaiining of 1P networks. Tlye Sccnnd arliclc, by Li, IIamdi, atid Jiang, describcs the IETF QoS framcwork, specifically t h c integrntod services model (IiitScrv) and Rcsnurce Hesorvation Protocol (RSVP), diffcrenrial scivice (DS) architecture, multiprotocol labcl switching (MPLS), and the buffer managcmciit and packct discnrtl ntccbaaistn. l’hcii? thc authors discuss two different suliitioris offcrcd by two vendors that offer I P tclepliony scrviccs. These exatnplcs arc used to illustrate how rcal systems arc iniplementcd. Afterward, they present a ncw DS architccturc with a now1 hnffer maiiagcnierit and packet discard mechanism and show that it substantially improvcs voice pcrformance over thc curretit best-cffort Internet. k i o , Lin, and Chou proposc in the third article :I VolP valuc-atldcd service for mobilc tietwork called iGSM. iGSM servicc pruvides user mobility to suhscribcrs, which allows t l i e ~ nL O use eithcr
L Table 1. Total&lrai IP telephony service mitrket: unit aiid revenue forecasls {source: Frost & S U ~ ~ ~ W F ~ ) .
(Curitintied oti y q c 46)
It Time F O R
MORE SOPHISTICATED QoS Testing? It's a fact, When it comes t o testing 00s (Duality of Service) on VolP and other packet transmissions, traditional technologies don't cut it. Tane testing, data testing, and subjective listening are simply unreliable.
That's why the AbacusrMtest system employs PSQM (Perceptual Speech Quality Measurement), the recognized worldwide standard.
Abacus PSQM (specified by ITU-T P.8611 is the only objective way t o quantify speech quality, letting you
tune your system t o achieve a ca nsistent qua Iity of service. It's
remarkably easyt can perform tests
channels simultaneously. No wonder more of today's leading telecommunications
companies employ Abacus PSQM.
Now, isn't it time your QoS testing became more sophisticated?
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+1-408-541-1010 www.rarak.com WOO0 h r a k Systems Corporation, Sunnpalo, CA USA fle@stefed by U1 to IS0 90171
624 nt ~.tomrot.or~p/poduttinnovalionr OR tirrlef24 on reader sewite curl
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CiSM hanctscts or H.323 terminals (IP phoiics or PCs) to BCCFSS telecommunication services. They describe how ttic iGSM registration, deregistration, and call delivery proccdures can bc implcmented without modifying thc GSM network. They stucly huw the tromboning effect in standard GSM system can bc avoitlrd when accessing the IP network. Then thcy invesligatc the misrouting problcm causecl by uscr mobility. r h o and Lin disciiss VoIP mobility in TP/cellular network intcrworking. They invcsfigatc how 11.323 gatewys provide intcrcorlnectiori belweeii 1P nctworks and switched circuit tietworks (SCNs). Thcy also describc how H.323 is to providc intcropcrabilily wit11 nther SCN tcrriiiIials whilc tnajor afforts arc fucuscd on IP/wircd SCN intcrworking. Thcn thcy discuss the potential problcms associatcd with inlei-working bctwccn U’ nctwcirks and ccllirlar networks through H.323 gatcw;iys. After thnt, they propcrsc B liglitwcight approach using tlic cxistirig call trnnsfer supplcincntnry wrvice t o providc VOW inobilily in tlic H.323 1P telcphoiiy nctworks. Thc ptoposcd approach iiscs cxisting componcnts in tlie 11.323 stnritlnrd, thcrehy :illowing VOW mobilily scrvicc in hybrid IP/ccllul;ir nchvorks to bc ii value-ndtlcd fcaturc in cxistitig 11.323-cnnipliant Internet tclcphnriy systcins. Iidii, Kawahmi, Takine, n i i d Oie discuss the pcrfoorinniice cvalunlion o f arctiitccturc for end-to-crid QoS prtrvisioning. They mainly divide thc Intcrncl intii three lypcs o f sulrnctworks: domain iie~works,access nctwcirks, aiid stiih tielworks. 'hey foctrs on issiics arising in tlic ~ornicrtwo nctworks €or cnti-to-end 0 0 s provisioning. First, thc i~cccssnetworks are of rather Ii)v-specil links, so dclay is still or m;ijor concern. They cxamiiie thc statistical dday hound through nuincricnl rcsults rlcrivcd from their andysis. The pcrformancc of slmc ways to reducc dclay is also invcstigaled. Thcn?they Cxmiitic low-bitratc voice flows so that cffcctivc flow rnxnagcnicnt can bc controlIed. Thcy pay more attenticin to 8 Clow aggregntioii sclicme, aut1 cvalunte its pctforniancc by annlyziiig its tilocking priihability ;ind the anioont d bandwidth reqiiircd, keeping it less than m n c acccptablc wilue. Thc nrticlc by Pazos, Kotelba, and MaIis describes how H.323 calls a r c cctablialicd using 11.323 galckccpcrs niid thc i.I.225.0call sctup proccdura to take nrfv:i~itngcof triiiisprt nvcr asynchrorioiis triirisfct’ mode (ATM) nctworks. This appmacll imposes control tcrinination un thc €1.323 and H.323 gatcways, siniplifyiri& tlic switched virtual conticctions (SVCs) for thc trnrisporr of H.323 Kcill-Tilnc Transport Protncol (RTI’) mcrlia slrcams. Thc articlc also discusses tlic opciiing oC n logical clinnricl xnd how H.245 mcssagcs arc uscd to providc the ncccssaiy infoormiition to cstnblisli SVCs. ?‘his iiicludcs tlic rnzchanisin to redircct traffic lo Lhc H.323-H.323 gateway. Tlic articlc hy Rergniark and Kcslii~vtlescribcs the r1.X project at Coriicll, which is an opcii source, portablc, progrsinmflblc platform for developing rriiiltiniudal a p p l i c a t i o n s (ix., applications that span l h c tclcphonc nctwork ancl the Intcrnct). As nri exiimplc, il plione rccorder dlciws 0111: to usc n telephone tu create a rccorded mcss:ige that will ITC slorcd in ii server 0 1 1 the Inkmet. pctlorniancc nieasurcrncrils (c.g., latcncy) of rhc ITX 2iavc liceti reportcd. Commercial conipw nies iirc cirrrently tcsting tlic ITX. Finally, the ‘lCP/IP protocol was dcvclopetl for nori-rcaltime k i t t i transmissioii and hcncc docs not pmvidc YoS giiarantces CO real-time applications such as IP tclcptiony. I lowcver, IF tclephny allows integration cif many applicalions and services siich as integration of rliita, voicc, iind fax, virlco tclcphony, tnidliplc telephone lines, support of multiptc voicc qualilics, antl cnlinncerl telcconfcrcticitig which cannot casily be support-
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cd by the circuit-switched teicpiione nctwork. Despite tlie
advantage of IP telephony antl t h e fact that i t is gaining moinctitiim mid popularity, a lot of technical issiics, such iis pwckct loss, nctwork delay, and packetization delay, still need 10 bc solved lo make it uscful in practice. In thc meantime, a number of commcrcial products arc already availablc in tlie markct. The articlc by Bassan, Nayandnro, and Atiquzzarnari presents an overall, veiy broad siirvey of the applications and services supported by 1P tclcptinny, thc technical chnlleiigcs IP telephony faccs, and sonic IP telephtriiy products (along with their technical basis atid thc scrvices thcy providc) available 011 thc market. ?‘hc articlc is mcaiil to providc an overnll picturc of thc state of thc art atid future ol1P tclephony. BlOG RAPHIES MUHSEN G U I ~ NISMI I (
[email protected]) is currently chair of the Compuler Science Department a t the University of Wert Florida, Pensacoh. From 1996 to 1999 hc was an associate professor of electrical and comput-
cr engineering at the University of Missouri-Columbia. His research intefests include computer networks, design and analysis of computer systems, parallel and distributed computing, fault-tolerant systems, modeliny and performance evaluation of commtrnication systems, wireless communications and computing, and optical interconnection networks, He has scrved as a guest editor for IEEE Communications Magazine, Informaiica. International Journal o f Computer Systems and Networks, Intcrnafioional Journal of Communication Systems, and lnternafional h u rn a/ o f Computing Research. He is founder and Edltor-In-Chief of a new joufnal entitled Wirele5s Systems and Computing (Wiloy). He is tho author of two books: Designing AT# Switcliing Networks (McGraw-Hill, 1999)and Optical Networking and Csmputing for Multimedia Systems (Marcol Dckker, to appear Pecemhcr 2000). He is program chair of PDCS 2000 and AN55 2001, 1 le has more than 100 publications in refereed journals and conferences. He received his B,S. and M.S. deyrees in electrical engineering; and M.S. and Ph.0. degrees in computer engineering in 1984, 1986, 1987, and 1990, rospectivcly, from Syracuse University, New York. He i$a member of the IEEE Computer Society, ASEE, ACM, OSA, SCS. and Tau Beta Pi. AMMAI~RAYES(
[email protected])is a solution^ manager and principal solutions architect at Cisco Systems. Hc is currently working on network managemenVopcration support systems for IP wireless. fixed broadband wireless, IP. ATM. VaIP, and WDM networks. Prior to joining Cisco Systems, he was a director in the Traffic Capacity Management and Planning Department of Telcordia Technologies (formcrly Bellcore). He has authorcdicoauthored over 30 books, patents, and papers on advances in numerous communications.relatcd technologies including a recent book on ATM switching and nctwork design published by McGraw Hill. He receivcd his B.5. and M.S. deqrccs in electrical engineering from the University of illinois a t Urbana in 1986 and 1988, re~pectively.He received his D.Sc. dcgrce in electrical engincoring from Washington University, St. Louis. Mlssotiri, in 1994, where lie rmeived thc Outstanding Graduate Student Award in Telecommunications. He has served as a boaid member of IEEE Computer Society press and is currently B member of the international Advisory Committee of the IEEE IP-Oriented Operations and Management Workshop (fPOM). He i s dso Industry Liaison Chairman of the lntcrnational Confcrence on Parallel and Distributed Computing and Syslcms. MOHAMMED ATIQUZZAMAN (
[email protected]) mceived M Sc. and Ph.D. deyrecs in electrical engineering and electronics from the University of Manchester I n 9 tute of Scicnce and Technology, United Kingdom. Currently he i s a faculty member in the Department of Electrical and Computer Engineering a t the university of Dayton. Ohio. He I S a senior editor of /E&€ Communications Magazine and European Trdnsacrionr,on Telocommunicafionr and International Journal and sew05 on the editorial boards of Computer Communialions Jour. nal and Telecommunicafion .Systems loomal. He has guest edited inany special issues of various journals, including feature topics about switching and traffic management for multimedia; architecture. protocol, and QoS; ATM switching antl A T M networks; and parallcd computing on clusters of workstations in IFEE CommunicationsMagazine, Europesn Traosartions on Te/ccommun ica iions, International Journal of Compupurer Systems Science g. Mgineering, and Parallel Computing. He has also scrved on the technical program committees of many national and international conferences including IEEE INFOCOM, IEEE GLOBECOM, AND IEEE Annual Conference on Local Computer Networks His current research interests are in next-generation Internet, broadband networks. multimedia over high-speed networks, T W I P over ATM, multiprocessors systems. and image processing, His book, TCPfIP over AT# N e t w o h (Artcch House), will be published in the second quarter of 2000. Ho has tauyht many short courses to industry in the area of computer and telecoinmunications networking, Hc has over 100 refcreed publications.
lEEE Coni~nu~~icalions Magazitic April 2UOO
