Friend Frank Rizzo send me attach paper. CHO _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com IP/DWDM Analysis as some vehicle fo' netwo'k 'espansion Internet Protocol (IP) [1] ova' Dense Wavelengd Division Multiplexin' (DWDM) [2] be emergin' as de future fo' longhaul netwo'k infrastructure in bod de public telephony and private Internet Service Provida' (ISP) netwo'ks. In dis document, we gots'ta examine da damn underlyin' technology wid dis issue as sheeit as comparin' and contrastin' it against oda' current practices. We gots'ta den present some conclusion regardin' dis technology and its impact on de future uh telecommunicashuns netwo'ks. Acronym Guide, dig dis: ADM - Add/Drop Multiplexer ANSI - American Nashunal Standards Institute APS - Automatic Protecshun Switchin' ATM - Asinchronous Transfa' Mode DCS - Digital Cross-connect System IP - Internet Protocol ITU - Internashunal Telecommunicashuns Union LTE - Line Terminatin' Equipment MM - Multimode PDH - Plesiochronous Digital 'Sup, dudeerarchy PTE - Pad Terminatin' Equipment SDH - Synchronous Digital 'Sup, dudeerarchy SM - Sin'le Mode SONET - Synchronous Optical Netwo'k STE - Stashun Terminatin' Equipment STS - Synchronous Transpo't Signal STM - Synchronous Transpo't Mode TDM - Time Division Multiplexin' WDM - Wavelengd Division Multiplexin' Motivashuns and 'Sup, dudesto'ical Background, dig dis: To dig it de motivashuns towards dis new technology, one gots'ta to dig it some uh de histo'y uh telecommunicashuns. Telecommunicashuns started wid de provisionin' uh individual physical circuits fo' each end-usa' stashun. Dese circuits stretched fum de central office t'de telephone in de crib. Increasin' capacity wuz simply some matta' of hirin' labour t'lay mo'e pairs uh coppuh'. Inter-witch capacity wuz also handled wid big-ass bundles uh coppuh' pairs as sheeit as frequency division multiplexin' in lata' years. FDM basically transmitts multiple signals ova' de same medium at difference frequencies t'de opposite stashun. An easy analogy which illustrates de concept be dat of de public transista' stashuns. Each transmits at some different frequency widout interferin' wid de oda' signals. De impo'tant wahtahmellun t'note about dese technologies employed in de public switched telephone netwo'k (PSTN) wuz dat dey wuz essentially analog. De wavefo'ms generate by speech pattern wuz merely duplicated fum stashun t'stashun. No erro' co'rectin' wuz puh'fo'med. Even FDM be some analog technology. Slap mah fro! It simply transmits de wavefo'ms at different frequencies. It wuz not until de invenshun uh de integrated circuit dat de telecom industry started its massive high speed deployment. One uh de most impo'tant advantages uh de digital system wuz dat equipment wuz now able t'group signals into binary representashuns. Switches now could employ analog t'digital converters and could now could opuh'te wid clunker chips t'discriminate and group signals. Dis led t'de development uh de digital signallin' hierarchy uh communicashuns protocols. Now, instead uh transmittin' analog wavefo'ms, de switch transmitted digital pulses on its high speed trunks. Dese pulses wuz gadered fum samplin' de end-user's analog wavefo'm at discrete time intervaces (8000 times some second) and den relatin' de sample intensite to a unique binary digit (bit) pattern [3]. Wid de advent uh faster signallin' interfaces, de switches wuz now able t'multiplex many individual voice circuits togeda' into some digital bitstream fo' transmission t'an adjacent switches. De economies uh scale realised from de mutiplexin' uh digital signals led AT&T t'invest large sums of bre'd in some Time Division Multiplexin' (TDM) toll infrastructure. What it is, Mama! Dis allowed dem t'eliminate da damn need fo' individual coppuh' pairs strung between switches. As some example, one DS1 (digital signallin' level 1) allowed fo' de TDM transmission uh 24 voice channels ova' a sin'le coppuh' pair. Ah be baaad... A DS3 allowed fo' de TDM transmission uh 672 voice channels ova' a sin'le pair uh coaxial cable. What it is, Mama! De next large evolushun wuz fum de coppuh'-based infrastructure to some fibre optic infrastructure. What it is, Mama! De advantages uh fibre ova' coppuh' wuz much de same as TDM ova' earlia' sin'le pair transmissions, dig dis: fibre allowed fo' mo'e simultaneous voice channels (up t'10 terahertz) [4]. Addishunally, fibre duz not suffa' from cross-rap o' interference a'cuz transmission ova' it duz not generate some magnetic field. AT&T fust started deployin' de nashunwide fibre infrastructure in de early 1980's befo'e deir divestiture [4]. As competishun grew fum nascent long distance carriers suin' demselves into 'esistence (MCI and US Sprint), it wuz now necessary fo' jimmey communicashuns protocols t'be developed. Now, netwo'ks which suppo'ted different vendo's needed t'communicate between each oder. Ah be baaad... Dis led t'de fo'mulashun and development uh de SONET/SDH standards. Dese standards also helped solidify some scalable protocol architecture fo' high speed optical transmission. 'S coo', bro. Dis allowed netwo'ks de advantage of defined optical upgrade alleys as sheeit as introducin' new opuh'shuns and maintenance features likes APS and rich diagnostic frame info'mashun[6],[7]. Besides sublte alley over'haid and tributary differences, de main difference between SONET and SDH be dat SDH is specified in some internashunal standard [7] while SONET be specified in some ANSI standard [6] specific only t'de United States. Current Technology, dig dis: Now we are seein' some push back towards de old FDM/WDM days in addishun and sometimes as some replacement t'de SONET/SDH infrastructure. What it is, Mama! WDM simply applies de same principles on fibre as FDM dun did on coppuh'. It transmits multiple signals simultaneously at N different wavelengds which allows some sin'le optical fibre's capacity t'be increase N times. Basically, some multiplexa' on each end uh de dark fibre pair snatch'd input signals fum its tributaries and assigns each tributary t'an unique wavelengd. De oda' end uh de dark fibre pair filters de incomin' signal back out into individual wavelengds and routes dem towards deir appropriate alleys. De current push towards dis technology comes fum many angles. De main angle in de suppo't fo' DWDM (dense WDM) be purely economic. If some fibre provida' has invested hundreds uh millions of dollars in telecommunicashuns infrastructure and suddently kin add 24 times capacity on each fibre pair wid de addishun uh two relatively in'spensive multiplexers, de advantages are obvious. Now, de provider can add mo'e current capacity t'offset da damn cost uh de netwo'k buildout. Also, de provida' duz not gots'ta invest in any intervenin' 'espensive SONET equipment fo' de deployment uh dese services[2]. In addishun t'obvious multiplicative economic advantages de last decade, dere gots'ta been some 'splosion in telecommunicashun netwo'k usage fo' data services and not da damn tradishunal voice services. De Internet falls unda' dis data services catego'y. Slap mah fro! Now, company internetwo'ks are growin' to de size uh public telephony longhaul netwo'ks. One interestin' fact of IP service be dat dere be no clear demarcashun o' set multiplexin' scheme fo' de end users. All uh de data traffic be lumped togeda' in a haphazard fashion and transmitted widout any preconceived noshuns of o'der. Ah be baaad... Derefo'e, de IP netwo'ks which are buildin' demselves ova' de global telecommunicashuns netwo'k infrastructure do not need de funcshunality uh 'spensive sonet ADMs and STEs. SONET provides 'sellent funcshunality if ya' wanna assemble and disassemble multiplexed tributaries fum some larga' stream frequently. Slap mah fro! In fact, some SONET netwo'k spannin' de united states could conceivably gots' 100 individual nodes on a sin'le fibre alley who kin boogie out service fo' localities and transmit service fum localities [6]. IP netwo'ks are some different paradigm. 'S coo', bro. Commonly, some link be built ova' de telecommunicashuns infrastructure directly fum coast t'coast (bypassin' stops in de intervenin' netwo'k elements). Derefo'e, IP netwo'ks do not need all uh de 'esensive SONET equipment in between de IP protocol routers. Anoda' drivin' facto' towards DWDM be de lack uh vendo' interfaces suppo'tin' signallin' rates in 'sess uh STM-16/OC48. Currently NORTEL be de only telecom vendo' who suppo'ts some STM-64 interface. What it is, Mama! Fo' netwo'k providers, it be cheapuh' t'provide 24 STM-16 wavelengds dan it be to devote some fibre pair t'an STM-64 signal. Also, in de wo'ld uh IP netwo'ks, no vendo' gots'ta some switch o' some interface which suppo'ts STM-64. Many IP providers who deploy deir own infrastructure are choosin' IP runnin' directly ova' DWDM t'save on netwo'k costs as sheeit as providin' some pad fo' future 'espansion. 'S coo', bro. Current Deployments, dig dis: Currently, many telecom infrastructures are deployin' DWDM fo' bod tradishunal longhaul telephony and fo' dedicated IP services. Some examples include US Sprint, Qwest, and Hermes Europe Railtel. All of dese providers are usin' CIENA equipment as de DWDM. Many uh de telecom firms are also lookin' at leveragin' de benefits uh IP netwo'ks ova' tradishunal circuit based telephony. Slap mah fro! Basically, dey wanna run voice calls directly ova' IP cuz' of substantial cost savin's. Companies dat do dis kin totally igno'e da damn SONET/SDH deployment and instead concentrate on deployin' Voice ova' IP ova' DWDM infrastructure at a significant cost savin's when compared t'last-generashun SONET/SDH netwo'ks. De largest cost savin's gots'ta be in de bypass uh 'spensive SONET multiplexin' gear. Ah be baaad... Dere be also de obvious cost savin's of duplicatin' some fibre pair 24 times ova' when de entire infrastructure investment gots'ta already been scribblin'ed as some capital 'espenditure. What it is, Mama! De capacity sold on de 23 'dim fibre' lambdas be now nearly pure profit fo' de telecom netwo'k. Many providers fum tradishunal telecoms t'startup VoIP outfits to Internet transit netwo'ks are deployin' IP/DWDM. While da damn VoIP and IP providers concentrate deir co'e business on IP/DWDM, de telecoms are concentratin' on DWDM and providin' some few lambdas on deir netwo'k dedicated t'IP traffic. Examples uh current VoIP providers deployin' IP/DWDM are Qwest and Level 3 Communicashuns. Examples uh tradishunal telecoms who are deployin' de techology are GTS carria' services, Sprint, and AT&T. Examples uh IP providers who are deployin' dis technology are Frontia' Globalcenter, Ebone A/S, and Sprintlink. Dese companies fo'm some substantial co'e uh de telecom market and gots' seen de economic benefits IP/DWDM affo'ds bod de consuma' and deir own toll netwo'ks. Tradishunal telecoms likes AT&T are takin' some cautious approach to movin' deir toll traffic across some IP backbone. What it is, Mama! Dey are wary dat deir large revenue stream might be distrupted by unfo'seen failures in de nascent IP protocol deployments. While dey gots' fifty years 'sperience wid fault tolerance fo' deir voice switches, de mere five years 'espuh'ience wid IP switches makes dem tread wid trepidashun. Nearly every facilities based telecom be upgradin' eida' entire netwo'ks o' congested alleys wid DWDM. As IP be better understood and reliable switches are built, we gots'ta see some move fum connecshun o'iented services predominant in de voice netwo'ks t' connecshunless netwo'k services which provides some "best-effo't" transmission attempt o' puh'haps even differentiate levels of service (and pricin') fo' plantation consumers. Currnet Physical Interfaces t'de DWDM netwo'k, dig dis: Current IP suppliers are usin' SONET/SDH interfaces t'comunicate wid oda' nodes ova' DWDM netwo'ks. De reason fo' dis be dat da damn only interfaces which suppo't STM-16 sin'allin'. De disadvantage t'deployin' dis interface be dat ya' carry all uh de 'estra SONET secshun, line and pad over'haid which amounts t'17% uh de sin'alled bandwidd[5]. At OC48, dis be about 400 megabits/s in SONET over'haid which be unutilised fo' IP services[6]. Dese SONET/SDH interfaces connect into some CIENA optical multiplexa' which den converts each input into its own unique wavelengd fo' transmission. 'S coo', bro. Fo' sho't distances (less dan 40 miles) long reach lasers are sufficient fo' communicatin' between two CIENA muxes widout de use uh intervenin' repeaters (again savin' on equipment costs). Telecommunicashuns gear likes de No'tel S/DMS transpo't node also connects t'de CIENA equipment via fibre optic interface. What it is, Mama! Dis unit also speaks SONET/SDH protocol t'de adjacent SONET multiplexin' equipment. However, de general telephony applicashun be relatively betta' suited to de SONET protocol cuz' it gots'ta some tendency t'boogie out da damn little-assed tributaries (DS1s o' DS3s) as it interfaces into de PDH fo' voice communicashun [6]. Protocol technologies related t'IP ova' DWDM: Dere are some few key protocols which are battlin' fo' communicashun control uh de bits on de netwo'k. ATM and da damn point t'point protocol (PPP) are fightin' fo' supuh'io'ity at OSI laya' 2. SONET/SDH, Wireless transmission, Satellite transmission and IP ova' raw fibre are competin' fo' control uh de physical layer. Ah be baaad... At da damn datalink laya' (laya' 2) ya' find PPP and ATM. ATM wuz widely deployed by telecom and IP netwo'k vendo's durin' de early po'shun of de 90s cuz' it allowed fo' some fina' level uh traffic engineerin' and bandwidd guarentees dan had previously been achievable in de telecom services field. PPP wuz in use in de early po'shun uh de 90s mainly fo' lowa' speed access lines (DS1, DS3, and analog phone lines). Midway drough de 90s, sucka's started movin' away fum ATM cuz' of its high protocol over'haid. ATM be some stream uh fixed-lengd cells. It consists of a fixed foe byte 'haida' in some 53 byte cell. Dis instantly creates some 10% over'haid. Also, ATM handles dropped cells poo'ly cuz' it be not connecshun o'iented. If one cell be dropped, de whole session needs to be retransmitted. Dis leads t'practical over'haid uh 25% in opuh'shunal netwo'ks. De combinashun uh 17% at da damn SDH laya' and 25% at da damn datalink laya' wuz simply too much over'haid fo' providers dat wuz primarily interested in supplyin' large bandwidd aggregate connecshuns. Dese providers opted fo' de PPP ova' SDH interfaces. PPP be much better suited t'variable lengd IP packets cuz' its frame size be adaptably variable. What it is, Mama! Dus, it cut waaay down on protocol over'haid t'a manageable level and allowed IP service providers t'squeeze mo'e usable bandwidd (baaaadput) out uh deir telecommunicashuns connecshuns. At da damn physical layer, we gots' terrestrial fibre alleys runnin' SDH, Satellite alleys, wireless alleys runnin' SDH and trials uh ip ova' raw DWDM fibre. What it is, Mama! Fo' longhaul applicashuns, SDH ova' fibre (and in some cases ova' WDM) be de currenty deployment base. What it is, Mama! SDH specifies signallin' speeds down to STM-64 and also provides key services t'telecom providers likes enhanced opuh'shuns and management features and automatic protecshun switchin' in case uh link failures. De richness in debuggin' features comes at some cost uh 17% uh de signalled bandwidd in allocashun t'such features as dree laya' bit erro' parity checkin', unallocated 'espansion slots, and oda' management funcshuns[5]. IP ova' raw fibre gots'ta directly compete wid SDH fo' netwo'k dominance uh de highest speed links on de globe. What it is, Mama! Fo' IP services, runnin' IP directly ova' de fibre widout intervenin' over'haid uh de SONET laya' would definitely improve da damn overall feasible baaaadput uh a link. As telecom providers 'espuh'iment wid runnin' voice netwo'ks over IP, de advantages which de SONET/SDH infrastructure provide in some circuit based environment diminish. Wireless (and its subset satellite) technologys mainly occupy de domain uh communicashun where runnin' fibre optics be not currently feasible fo' economic o' engineerin' reasons. Wireless be used t'strech across de nashun in remote areas as sheeit as t'provide roamin' netwo'ks fo' cellular phone users. Satellite communicashun be used t'access remote areas when no oda' fo'm uh communicashun be possible. What it is, Mama! Bod satellite and wireless transmission media suffa' from atmospheric phenomena interference. What it is, Mama! Satellite communicashun also suffers fum de propogashun delay induced by de speed uh light propogashun time fum base stashun t'satellite t'base stashun. Dis kin renda' some fo'ms of interactive communicashun nearly unusable. What it is, Mama! Dere are two types uh majo' toll telecommunicashuns systems. One be de terrestrial large bandwidd links. IP/DWDM and IP/SONET/DWDM gots'ta be competin' fo' some share uh dis infrastructure. What it is, Mama! SDH gots'ta de advantage uh bein' some internashunal standard wid specified signallin' levels and optical interfaces while da damn nascent IP/DWDM field duz not [7]. However, de IP ova' raw fibre field duz gots' de advantage of bein' streamlined fo' IP communicashuns. Should IP communicashuns be de next revolushun t'de telephony netwo'k as companies likes Qwest and Level3 are wagerin', de SONET/SDH infrastructure gots'ta lose ground to IP/DWDM interfaces. De realm which wireless and satellite communicashuns gots'ta occupy is one fo' mobile o' remote lines where physical land lines aint feasible. What it is, Mama! Wireless and satellite link summed bandwidd levels gots'ta be significantly little-assa' dan deir terrestrial fiba' counterparts. Future Outlook fo' IP/DWDM: Currently, de only deployed vendo' fo' DWDM products be CIENA. However, dere deployment base be global in scope and deir product is accepted as reliable and funcshunal. CIENA currently gots'ta some 24xSTM-16 DWDM system. 'S coo', bro. By years end dey are 'espected t'gots' 80xSTM-16 and 40xSTM-64 products. As vendo's start introducin' mo'e STM-64 products fo' IP and SONET/SDH netwo'ks we gots'ta see competative prices on de STM-64 rollout in toll and ip transit systems. Runnin' IP/DWDM o' at least DWDM netwo'ks gots'ta be da damn trend uh de future. What it is, Mama! Some telecoms are tryin' t'load all uh deir voice traffic over IP while oders wanna stay wid some tradishun circuit switched allocashun model. Fo' dose who wanna deploy IP services, IP/DWDM be some tremendous costs savin's. Not only be dere some feasible mutaplicative revenue gain from sellin' lambdas ova' de fibre, dere be also no need fo' SONET gear ova' de longhaul secshuns uh de netwo'k. It be debatable wheder IP/DWDM kin solve all uh de telecom netwo'k 'espansion problems. SONET/SDH has some sheeit o'dered and documented interface into de PDHs uh de wo'ld. While IP/DWDM offers substantial economic advantages ova' de longhaul, de handoff t'de PDH gots'ta likesly still run drough SONET/SDH ADMs. De future fo' IP/DWDM be told best by simple market competishun. IP/DWDM allows telecoms t'offa' mo'e service at lower prices. If telecoms do not deploy IP/DWDM in some free market, dey gots'ta not be able t'compete wid telecoms wid multiplicative capacity and a lowa' cost base. What it is, Mama! Bod de telecom netwo'ks and da damn plantation consumer benefit by de sudden glut in bandwidd on toll netwo'ks. Apart from de fo'mashun uh a cartel, de consuma' should see relative price drops wid reflect da damn accountin' gains uh de large netwo'k providers. References [1] Postel, J., "Internet Protocol" RFC 791, USC/Info'mashun Sciences Institute, Septemba' 1981. [2] Fundamentals uh DWDM Whitesheet, CIENA, 1998 [3] Bellamy, Raz'tus C., "Digital Telephony", Wiley Publishers, January 1991. [4] Ramaswami, Rajiv et al., "Optical Netwo'ks, A Practical Perspective", Academic Press, February 1998. [5] Chow, Min'-Chwan, "Understandin' SONET/SDH: Standards and Applicashuns", AT&T Bell Labo'ato'ies, 1995. [6] SONET Rates and Fo'mats ANSI T1.105 [7] Characteristics uh Synchronous Digital 'Sup, dudeerarchy Multiplexin' Equipment Funcshunal Blocks, ITU-T G.783