1 A Mini Project Report on “BROAD BAND ACCESS TECHNOLOGIES” Submitted in partial fulfillment of the requirements for the award of the Degree of BACHELOR OF TECHNOLOGY in ELECTRONICS AND COMMUNICATION ENGINEERING By Satish Masina (09P31A0486) Under the supervision of Mr. M. Kranthi Kumar (M Tech) Assistant Professor, ECE Dept.DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING SRI SAI ADITYA INSTITUTE OF SCIENCE AND TECHNOLOGY (Affiliated to JNTUK, Kakinada & Approved by AICTE, New Delhi) Surampalem, ADB Road, E. G. Dt., A.P - 533437. 2009– 2013
2 CERTIFICATE DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING This is to certify that Mr. MASINA SATISH participated in the Mini project underthe title of TELECOM TECHNOLOGIES, BSNL, KAKINADA, EAST GODAVARI Dist.,ANDHRA PRADESH, during period from 07-05-2012 to 20-05-2012 and successfullycompleted, the same as record of bonafied work carried out by the above student under myguidance & supervision.Internal Project Guide Head of the DepartmentM.Kranthi Kumar (M Tech) Mr.R.V.V.KRISHNA M Tech, (Ph.D)Assistant Professor Associate Professor
3 ACKNOWLEDGEMENTMini project has an important role in a shaping up an engineering student for practicalknowledge how a keeping him update with latest technology. First of all, I would like to expressmy attitude towards Mr. V. Hanumantha Rao for his guidance throughout our mini projectwork. With great pleasure we want to take this opportunity to express our heartfelt gratitude toall the people who helped in making this mini project work a grand success.We thank Mr. V. Ramesh Babu, D.E (Internal) of BSNL, Rajahmundry for extending theirutmost support and cooperation in providing all the provisions for the successful completion ofthe project.First of all we are highly indebted to Principal Dr. CH. Srinivasa Rao for giving us thepermission to carry out this mini project.We would like to thank Mr. R. V. V. KRISHNA, Head of the Department of Electronics andCommunication Engineering, as our project guide for giving valuable suggestions.Last but not the least, we express our sincere thanks to Asst. Prof. M. Kranthi Kumar for hiscontinuous care towards our achievements.We would like to thank the Other Teaching Staff of ECE Department for sharing theirknowledge with us.
4 ABSTRACT It is not viable to expand the telecom network in India substantially at the prevalent levelof per-line investment. However, systems based on new technologies, many developed in India,promise to more than halve the investment required. This article looks at the telecom scenario, the new technologies, the Indian productsbased on these technologies, and the cost reductions they promise. The provision of widespreadInternet service with low access tariff is an important aspect of the new approach. In the era of Modernization and Globalization communication became the part andparcel of human life, whereas BSNL is one of its kinds in such a communication. The term broadband refers to a telecommunications signal or device ofgreater bandwidth, in some sense, than another standard or usual signal or device (and thebroader the band, the greater the capacity for traffic). The broadband technology you choose will depend on a number of factors. These mayinclude whether you are located in an urban or rural area, how broadband Internet access ispackaged with other services (such as voice telephone and home entertainment), price, andavailability. Broadband communications technology can be divided broadly into wire linetechnologies and wireless technologies. Advantages of Broadband are Always on (Not on shared media), Fast (speed rangingfrom 256 kbps), No disconnection, No additional access charge, Telephone and Datasimultaneously
5 INDEXTABLE OF CONTENTS Pg no 1. BSNL OVERVIEW A. External/Internal Infrastructure B. BSNL Service 2. NATIONAL INTERNET BACKBONE (NIB) A. Architectural principles B. Infrastructure. C. Economy 3. BROADBAND A. Digital Subscriber Line (DSL) B. Asymmetric Digital Subscriber Line (ADSL) C. Very high Digital Subscriber Line (VDSL) D. Digital Subscriber Line Access Multiplexer (DSLAM) E. Routing. F. Broadband Remote Access Server (BRAS) G. Router H. Service Control Module I. Wi-Fi J. Wi-Max
6 INTRODUCTION TO BSNL Bharat Sanchar Nigam Ltd. formed in October, 2000, is Worlds 7th largestTelecommunications Company providing comprehensive range of Telecom services in India:Wire line, CDMA mobile, GSM Mobile, Internet, Broadband, Carrier service, MPLS-VPN,VSAT, VoIP services, IN Services etc. Presently it is one of the largest & leading Public Sectorunits in India. BSNL has installed Quality Telecom Network in the country and now focusing onimproving it, expanding the Network, introducing new Telecom services with ICT applicationsin villages and wining customers confidence. Today, it has about 46 million line basic telephonecapacity, 5.06 Million WLL capacity, 52 Million GSM Capacity, more than 38302 fixedexchanges, 46565 BTS, 3895 Node B ( 3G BTS), 287 Satellite Stations, 614755 RKM of OFCCable, 50430 RKM of Microwave Network connecting 602 Districts, 7330 cities/towns and 5.6Lakhs villages. BSNL is the only service provider, making focused efforts and planned initiatives tobridge the Rural-Urban Digital Divide ICT sector, in fact there is no Telecom operator in thecountry to beat its reach with its wide Network giving services in every nook & corner ofcountry and operates across India except Delhi & Mumbai. Whether it is in accessible areas ofSiachen glacier and North-eastern region of the country, BSNL serves its customers with its widebouquet of Telecom services. BSNL is Numero-uno operator of India in all services in its license area. The companyoffers vide ranging & most transparent tariff schemes designed to suite every customer. BSNL Comprises of Cell One 90.09 Millions of 2G cellular customers and 88,493 3Gcustomers as on 30.11.2009. In basic services, BSNL is miles ahead of its rivals, with 35.1million Basic Phone subscribers i.e. 85 per cent share of the subscriber base and 92 percent sharein revenue terms.
7 BSNL has more than 2.5 million WLL subscribers and 2.5 million Internet Customerswho access Internet through various modes viz. Dial-up, Leased Line, DIAS, and Account lessInternet (CLI). BSNL has been adjudged as the NUMBER ONE ISP in the country. BSNL has set up a world class multi-Gigabit, multi-Protocol convergent IP infrastructurethat provides convergent services like Voice, Data and video through the same Backbone andBroadband Access Network. At present there are 0.6 million Data One broadband customers. The company has vast experience in Planning, Installation, Network integration andMaintenance of Switching & Transmission Networks and also has a world class ISO 9000certified Telecom Training Institute.
8 BHARAT SANCHAR NIGAM LIMITED (BSNL) OVERVIEW Bharat Sanchar Nigam Limited (abbreviated BSNL) is a state owned telecommunications. Company head quartered in New Delhi, India. BSNL is one of the largest Indian cellular service providers, with over 87.1 million subscribers as of April2011, and the largest land line telephone provider in India. However, in recent years the companys revenue and market share plunged into heavy losses due to intense competition in Indian telecommunications sectorBSNL is Indias oldest and largest communication service provider (CSP). It had a customer base of 90 million asof June 2008. It has footprints throughout India except for the metropolitan citiesof Mumbai and New Delhi, which are managed by Mahanagar Telephone Nigam Limited (MTNL). As of June30, 2010, BSNL had a customer base of 27.45 million wire line and 72.69million wireless subscriber It is India’s largest telecommunication company with 24% market share as on March 31st2008.Itsheadquarters are at Bharat Sanchar Bhawan, Harish Chandra Mathur Lane, New Delhi. It has the status ofMINI RATNA, a status assigned to public sector companies in India.External/internal infrastructure:External infrastructure: Lines and cables(U/G include)Internal infrastructure: Battery, PowerPlant E/A, A/C plant, MDF,Switches (C-DOT, OCB 283, EWSD, AXE etc),Leased Lines (MLLN), Broad Band, MPLS VPN.
9Interesting Facts: There are 2 million BSNL mobile connections in rural India (a record, no other connection is as famous as BSNL in rural areas) BSNL supplies phone lines to all other network such as Airtel, Vodafone etc. Largest pan India coverage-over 11000 towns & 3 lakh Villages. India’s No. 1 wireless service provider with more than 50 Million customers. An incredible speed of 2mbps is only offered by BSNLBSNL Services: 1. BSNL LANDLINE NEW TELEPHONE CONNECTION PERMANENT CONNECTION CONCESSION IN RENTALS SHIFT OF TELEPHONE TRANSFER OF TELEPHONE TELEPHONE TARIFF
102) BSNL MOBILE POSTPAID PREPAI D UNIFIED MESSAGING GPRS/WAP/MMS DEMOs TARI FF SMS & BULK SMS3) BSNL WLL4) INTERNET SERVICES NETWORK BROADBAND TYPES OF ACCESS INTERBET TARIFF DIAL-UP INTRENET Wi-Fi5) BSNL BROADBAND REGISTER ONLINE TARIFF CHECK USAGE FAQ
116) ISDN ISDN TARIFF7) VIDEO CONFERRENCING OVERVIEW TARIFF FAQ8) AUDIO CONFERRENCING OVERVIEW TARIFF FAQ9) TELEX/TELEGRAPH TELEX/TELEGRAGH TARIFF10) INET OVERVIEW SERVICES ON I NET USING ON I NET11) EPABX EPABX CENTREX TRANSPONDER
12 National Internet Backbone (NIB): The Internet backbone refers to the principal data routes between large, strategically interconnected networks and core routers in the Internet. These data routes are hosted by commercial, government, academic and other high capacity network centers, the Internet exchange points and network that interchangeInternet traffic between the countries, continents and across the oceans of the world.Architectural Principles: The Internet, and consequently its backbone networks, does not rely on central control orcoordinating facilities, nor do they implement any global network policies. The resilience of the Internet resultsfrom its principal architectural features, most notably the idea of placing as few network state and control functionsas possible in the network elements, but instead relying on the endpoints of communication to handle most of theprocessing to ensure data integrity, reliability ,and authentication. In addition, the high degree of redundancy oftodays network links andsophisticated real-time routing protocols provide alternate paths of communications forload balancing and congestion avoidance.
13Infrastructure: The internet backbone is a conglomeration of multiple, redundant networks owned by numerouscompanies. It is typically a fiber optic trunk line. The trunk line consists of many fiber optic cables bundledtogether to increase the capacity. The backbone is able to re route traffic in case of a failure. The data speeds ofbackbone lines have changed with the times. In 1998, all of the United States backbone networks had utilized theslowest data rate of 45 Mbps. However the changing technologies allowed for 41 percent of backbones to havedata rates of 2,488 Mbps or faster by the mid 2000s. The FCC currently defines "high speed" as any connectionwith data speeds that exceed 200 kilobits per second. An Azerbaijani based telecommunication company, DeltaTelecom, has recently developed a very efficient trunk line with possible speeds of to 1.6terabits per second.Internet traffic from this line goes through the countries of Iran, Iraq and Georgia. Fiber-optic cables are themedium of choice for internet backbone providers for many reasons. Fiber-optics allows for fast data speeds andlarge bandwidth; they suffer relatively little attenuation, allowing them to cover long distances with few repeaters;they are also immune to crosstalk and other forms of EM interference which plague electrical transmission.Modern Backbone: Because of the enormous overlap between long distance telephone networks and the internet backbonenetworks, the largest long distance voice carriers such as AT&T, MCI, Sprint and west also own some of thelargest internet backbone networks. These backbone providers will then sell their service to ISPs. Each ISP has itsown contingency backbone network, and at the very least, is equipped with an outsourced backup. These networksare intertwined and criss-crossed to create a redundant network. Many companies operate their own backbonesthat are all interconnected at various NAPs around the world. In order for data to navigate through this diverse webthat the backbone creates, backbone routers are desperately needed. These backbone routers are routers that arepowerful enough to handle information on the internet backbone, and they direct data to other routers in order tosend it to its final destination. Without these backbone routers, information would be lost since data would notknow how to locate its end destination. The very largest providers, known as Tier 1 providers, have suchcomprehensive networks that they never need to purchase transit agreements from other providers. As of 2000there were only five internet backbone providers at the Tier 1 level in the telecommunications industry.
14NIB in India:Indias backbone is very extensive due to a very large population. This country alone has nearly 250 millioninternet users as of 2009. Four of Indias top Internet Service Providers are Tata Communications, BSNL, MTNL,and Reliance Communications. Tata Communications is a Tier-1 IP network, with connectivity to more than 200countries across 400 Pops and nearly 1,000,000square feet (93,000 m2) of data center and collocation spaceworldwide. It is Indias largest provider in data center services and also operates Indias largest data center in Pune.The backbone structure keeps on getting stronger because of the huge number of new emerging mobile operatorswhich leads to decrease in prices due to competition in the market.Economy of the Backbone:Peering agreements: Backbone providers of roughly equivalent market share regularly createagreements called peering agreements. These agreements allow the use of anothers network to hand off trafficwhere is ultimately delivered. They usually do not charge each other for this use as they all get revenue from theircustomers regardless.Transit agreements: Backbone providers of unequal market share usually create agreements called transitagreements, and usually contain some type of monetary agreement.Regulation: Antitrust authorities have acted to ensure that no provider grows large enough to dominate thebackbone market. The FCC has also decided not to monitor the competitive aspects of the Internet Backboneinterconnection relationships, as long as the market continues to function well without regulationBroadband:
15 The term broad band refers to a telecommunications signal of greater bandwidth, in somesense, than another standard or usual signal (and the broader the band, the greater the capacity for traffic). Differentcriteria for "broad" have been applied in different contexts and at different times. Broadband intelecommunications refers to a signaling method that includes or handles a relatively wide range (or band) offrequencies, which may be divided into channels or frequency bins. Broadband is always a relativeterm, understood according to its context. The wider (or broader) the bandwidth of a channel, the greater theinformation-carrying capacity. In radio, for example, a very narrow-band signal will carry Morse code; a broaderband will carry speech; a still broader band is required to carry music without losing the high audio frequenciesrequired for realistic sound reproduction. A television antenna described as "broadband" may be capableof receiving a wide range of channels; while a single-frequency or Lo-VHF antenna is "narrow band" since it onlyreceives 1 to 5 channels. In data communications a digital modem will transmit a data rate of 56 kilobits perseconds (k bit/s) over a 4 kilohertz wide telephone line (narrowband or voice band). However when that same lineis converted to an non-loaded twisted-pair wire (no telephone filters), it becomes hundreds of kilohertz wide(broadband) and can carry several megabits per second (ADSL)Technology: The standard broadband technologies in most areas are ADSL and cable internet. Newertechnologies in use include VDSL and pushing optical fiber connections closer to the subscriber in both telephoneand cable plants. Fiber-optic communication, while only recently beingusedin fiber to the premises and fiber to the curb schemes, has played a crucial role in enabling Broadband Internetaccess by making transmission of information over larger distances much more cost-effective than copper wiretechnology. In a few areas not served by cable or ADSL, community organizations have begun to installWi-Fi networks, and in some cities and towns local governments are installing municipal Wi-Fi networks. Thenewest technology being deployed for mobile and stationary broadband access is Wi MAX.
16Broadband in DSL: The various forms of digital subscriber line (DSL) services are broadband in the sense that digitalinformation is sent over a high-bandwidth channel. This channel is located above (i.e., at higher frequency than)the baseband voice channel on a single pair of wires.Digital Subscriber Line:Digital Subscriber Line (DSL) is a family of technologies that provides digital data transmission overthe wires of a local telephone network. DSL originally stood for digital subscriber loop. Intelecommunications marketing, the term Digital Subscriber Line is widely understood to mean AsymmetricDigital Subscriber Line (ADSL), the most commonly installed technical variety of DSL. DSL service isdelivered simultaneously with regular telephone on the same telephone line. This is possible because DSLuses a higher frequency. These frequency bands are subsequently separated by filtering. The data throughput of consumer DSL services typically ranges from 256 Kb/s to 40Mbit/s inthe direction to the customer (downstream), depending on DSL technology, line conditions, and service-levelimplementation. In ADSL, the data throughput in the upstream direction, (i.e. in the direction to the serviceprovider) is lower, hence the designation of asymmetricservice. In Symmetric Digital Subscriber Line (SDSL) service, the downstream and upstream data rates areequal.Basic technology:
17 Telephones are connected to the telephone exchange via a local loop, which is a physicalpair of wires. Prior to the digital age, the use of the local loop for anything other than the transmission ofspeech, encompassing an audio frequency range of 300 to 3400 Hertz(voice band or commercial bandwidth)was not considered. However, as long distance trunks were gradually converted from analog to digitaloperation, the idea of being able to pass data through the local loop took hold, ultimately leading In currentpractice, speech is digitized by using an analog-to-digital converter sampling at a rate of 8000 samples persecond, capturing eight-bit values and producing a 64 kilobit per second data stream. According to theNyquist Shannon sampling theorem, if an input audio signal injected into such an analog-to-digital convertercontains frequency components higher than half of the sampling frequency, then such high frequencycomponents will be aliased by the system, and so must be blocked at the input by an appropriate low-passfilter in order to prevent such effects. Due to the presence of the low-pass filter, input frequencies above fourkilohertz (KHz)will be blocked, preventing the passage of arbitrarily high frequencies through the normaltelephone voice path The local loop connecting the telephone exchange to most subscribers has the capabilityof carrying frequencies well beyond the 3.4 kHz upper limit of POTS. Depending on the length and qualityof the loop, the upper limit can be tens of megahertz. DSL takes advantage of this unused bandwidth of thelocal loop by creating 4312.5 Hz wide channels starting between 10 and100 kHz, depending on how thesystem is configured. Allocation of channels continues at higher and higher frequencies (up to 1.1 MHz forADSL) until new channels are deemed unusable. Each channel is evaluated for usability in much the sameway an analog modem would on a POTS connection. More usable channels equates to more availablebandwidth, which is why distance and line quality are a factor (the higher frequencies used by DSL travelonly short distances). The pool of usable channels is then split into two differentfrequency bandsforupstream and downstream traffic, based on a preconfigured ratio. This segregation reduces interference.Once the channel groups have been established, the individual channels are bonded into a pair of virtualcircuits, one in each direction. Like analog modems, DSL transceivers constantly monitor the quality of eachchannel and will add or remove them from service depending on whether they are usable.Network Connectivity Diagram:
18Typical setup and connection procedures Physical connection must come first. On the customer side, the DSL Transceiver, or ATU-R, or more commonly known as a DSL modem, is hooked up to a phone line. The telephone company (telco) connects the other end of the line to a DSLAM, which concentrates a large number of individual DSL connections into a single box. The location of the DSLAM depends on the telco, but it cannot be located too far from the user because of attenuation, the loss of data due to the large amount of electrical resistance encountered as the data moves between the DSLAM and the users DSL modem. It is common for a few residential blocks to be connected to one DSLAM.When the DSL modem powers up it goes through a sync procedure. The actual process varies from modemto modem but generally involves the following steps:
19 1. The DSL transceiver performs a self-test. 2. The DSL transceiver checks the connection between the DSL transceiver and the computer. Forresidential variations of DSL, this is usually the Ethernet (RJ-45) port or a USB port; inrare models, a FireWire port is used. Older DSL modems sported a native ATM interface (usually, a 25 M bitserial interface). Also, some variations of DSL (such as SDSL) use synchronous serial connections. 3. The DSL transceiver then attempts to synchronize with the DSLAM. Data can only come into thecomputer when the DSLAM and the modem are synchronized. The synchronization process is relativelyquick (in the range of seconds) but is very complex, involving extensive tests that allow both sides of theconnection to optimize the performance according to the characteristics of the line in use. External or stand-alone modem units have an indicator labeled "CD", "DSL", or "LINK", which can be used to tellif themodem is synchronized. During synchronization the light flashes; when synchronized, the light stays lit,usually with a green color.The accompanying figure is a schematic of a simple DSL connection (in blue). The right side the shows aDSLAM residing in the telephone companys central office. The left side shows the customer premisesequipment with an optional router. This router manages a local area network (LAN) off of which areconnected some number of PCs. With many service providers, the customer may opt for a modem whichcontains a wireless router. This option (within the dashed bubble) often simplifies the connection DSL Connection schematicEquipment:
20The customer end of the connection consists of a terminal adaptor or in laymans terms" DSL modem". Thisconverts data between the digital signals used by computers and the voltage signal of a suitable frequencyrange which is then applied to the phone line. In some DSL variations (for example, HDSL), the terminal adapter connects directly tothecomputer via a serial interface, using protocols such as ethernet or V.35. In other cases(particularlyADSL), it is common for the customer equipment to be integrated with higher level functionality, such asrouting, firewalling, or other application-specific hardware and software. In this case, the equipment isreferred to as a gateway. Some kinds of DSL technology require installation of appropriate filters to separate, or "split",the DSL signal from the low frequency voice signal. The separation can take place either at the demarcationpoint, or with filters installed at the telephone outlets inside the customer premises. Either way has its practicaland economical limitations. See ADSL for more information about this. At the exchange, a digital subscriber line access multiplexer (DSLAM) terminates the DSLcircuits and aggregates them, where they are handed off onto other networking transports. In the case ofADSL, the voice component is also separated at this step, either by a filter integrated in the DSLAM or byspecialized filtering equipment installed before it. The DSLAM terminates all connections and recovers theoriginal digital information.Brief Functions of DSL Components:
21DSL CPEs: At customer premises. On end it connects telephone cable coming from exchange. At theother end, it connects to PC through Ethernet and Telephone through RJ-45 connectorDSLAM: called as DSL Access Multiplexer. It has a built in splitter which splits voice and data. Whilevoice follows the normal conventional path through exchange, data is aggregated and up linked throughEthernet Port (Gigabit Ethernet for 480 port and Fast Ethernet for lower DSLAM)LAN Switch: For aggregating multiple DSLAM and providing a common uplinkBRAS: called as Broadband Remote Access Server. First intelligent device in the whole chain. It terminatesthe customer session, authenticates, a lot IP addresses and keeps track of user session for billing along withRADIUSSSSS: Called as Subscriber Service Selection System. When customer logs in he will be welcome with thiscustomized screen from where he can select various range of service. This provides on demand servicewithout manual interventionRADIUS: This in conjunction with BRAS authenticates customer, upload customer profile in the SSSS andkeeps track of billingLDAP: It stores customer database viz username, password and the default services that itcan subscribe to.Provisioning: This is the most critical components for ensuring quick delivery of service.It ensures end-to-end provisioning of service right from DSL CPEs to DSLAM to Switchto BRAS to LDAPAsymmetric Digital Subscriber line (ADSL): The distinguishing characteristic of ADSL over otherforms of DSL is that the bandwidth is greater in the direction to the customer premises than the reverse,giving rise to is asymmetric characteristic. Providers usually market ADSL as a service for consumers toconnect to the Internet in a relatively passive mode: able to use the higher speed direction for the downloadfrom the Internet but not needing to run servers that would require high speed in the other direction Withstandard ADSL the band from 26.000 kHz to 137.825 kHz is used for upstream communication, while 138
22kHz-1104 kHz is used for downstream communication. Each of these is further divided into smallerfrequency channels of 4.3125 kHz. These frequency channels are sometimes termed bins.Very high bit rate digital subscriber line (VDSL):It is a DSL technology providing faster datatransmission (up to 52 Mbps downstream and16 Mbps upstream) Second-generation VDSL2 systems (ITU-T G.993.2 Approved in February2006) utilize bandwidth of up to 30 MHz to provide data rates exceeding100 M bits simultaneously in both the upstream and downstream directions. The maximum available bit rateis achieved at a range of about 300 meters; performance degrades as the loop attenuation increases. Currently,the standard VDSL uses up to 7 different frequency bandsDigital Subscriber Line Access Multiplexer:A Digital Subscriber Line Access Multiplexer(DSLAM, often pronounced dee-slam)allowstelephone lines to make faster connections to the Internet. It is a network device, located in the telephoneexchanges of the internet service providers, that connects multiple customer Digital Subscriber Lines (DSLs)to a high-speed Internet backbone line using multiplexing techniques. By placing additional remoteDSLAMs at locations remote to the telephone exchange, telephone companies provide DSL service tolocations previously beyond effective range.Path taken by data to DSLAM:
231.Customer premises: DSL modem terminating the ADSL, SHDSL or VDSL circuit andproviding LANinterface to single computer or LAN segment2. Local loop: The telephone company wires from a customer to the telephone company scentral office orto a Serving area interface, often called the "last mile" (LM).3. Central Office(CO): Main Distribution Frame (MDF): a wiring rack that connects outside subscriber lines withinternal lines. It is used to connect public or private lines coming into the building to internal networks. At thetelco, the MDF is generally in proximity to the cable vault and not far from the telephone switch. XDSLfilters: DSL filters are used in the Central Office (CO) to split voice from data signals. The voice signal can berouted to a POTS provider or left unused whilst the data signal is routed to the ISP DSLAM via the HDF (seenext entry).Handover Distribution Frame (HDF): a distribution frame that connects the last mile providerwith the service providers DSLAMDSLAM: A device for DSL service. The DSLAM port where the subscriber local loop is connectedconverts analog electrical signals to data traffic (upstream traffic for data upload) and data traffic to analogelectrical signals (downstream for data download).XDSL Connectivity diagramRole of DSLAM:
24 The DSLAM equipment at the telephone company (telco) collects the data from itsmany modem ports and aggregates their voice and data traffic into one complex composite "signal" viamultiplexing. The aggregated traffic is then directed to a telcos backbone switch, via an accessnetwork (AN) also called a Network Service Provider (NSP) at up to 10 G bit/s data rates. The DSLAM acts like a network switch since its functionality is at Layer 2 of the OSImodel. Therefore it cannot re-route traffic between multiple IP networks, only between ISP devices and end-user connection points. The DSLAM traffic is switched to a Broadband Remote Access Server where the enduser traffic is then routed across the ISP network to the Internet. Customer Premises Equipment thatinterfaces well with the DSLAM to which it is connected may take advantage of enhanced telephone voiceand data line signaling features and the bandwidth monitoring and compensation capabilities it supports. DSLAMs are also used by hotels, lodges, residential neighborhoods, and otherbusinesses operating their own private telephone exchange .In addition to being a data switch andmultiplexer, a DSLAM is also a large collection of modems. Each modem on the aggregationcard communicates with a single subscribers DSL modem. This modem functionality is integrated into theDSLAM itself instead of being done via an external device like a traditional computer modem. Liketraditional voice-band modems, a DSLAMs integrated DSL modems usually have the ability to probe theline and to adjust themselves to electronically or digitally compensate for forward echoes and otherbandwidth-limiting factors in order to move data at the maximum connection rate capability of thesubscribers physical line. This compensation capability also takes advantage of the better performance of"balanced line" DSL connections, providing capabilities for LAN segments longer than physically similarunshielded twisted pair (UTP) Ethernet connections, since the balanced line type is generally required for itshardware to function correctly. This is due to the nominal line impedance (measured in Ohms but comprisingboth resistance and inductance) of balanced lines being somewhat lower than that of UTP, thus supportingweaker signals (however the solid-state electronics required to construct such digital interfaces is morecostly).
25Tier 2 Network A Tier 2 Network is an Internet service provider who engages in the practice ofpeering with other networks, but who still purchases IP transit to reach some portion of the Internet. Tier 2 providers are the most common providers on the Internet as it is much easier topurchase transit from a Tier 1 network than it is to peer with them and then attempt to push into becoming aTier 1 carrierTier 1 Network: Although there is no authority that defines tiers of networks participating in the Internet, the mostcommon definition of a tier 1 network is one that can reach every other network on the Internet withoutpurchasing IP transit or paying settlements. By this definition, a tier 1 network is a transit-free network that peers with every other tier-1network. But not all transit-free networks are tier 1 networks. It is possible to become transit-free by payingfor peering or agreeing to settlements. It is difficult to determine whether a network is paying settlements ifthe business agreements are not public information, or covered under a non-disclosure agreement. TheInternet "peering community" is roughly the set of peering coordinators present at Internet exchanges onmore than one continent. The subset representing "tier 1"networks is collectively understood, but not published assuch. Strictly observing this definition of "tier 1" would exclude every network. For instance, many largetelephone companies are tier 1 networks, but they buy, sell, or swap fiber amongst themselves. Paymentsbetween companies are not all known, nor whether they cover peering connections.As a result, the term "tier 1 network" is used in the industry to mean a network with no overt settlements. Anovert settlement would be a monetary charge for the amount, direction, or type of traffic sent betweennetworks.
26Routing:Internet traffic between any two tier 1 networks is critically dependent on the peering relationship of thepartners, because a tier 1 network does not have any alternate transit paths. If two tier 1 networks arrive at animpasse and discontinue peering with each other (usually in auni lateral decision), single-homed customers ofeach network will not be able to reach the customers of other networks. This effectively partitions the Internetand traffic between certain parts of the Internet is interrupted. This has happened several times during thehistory of the Internet. Those portions of the Internet typically remain partitioned until one side purchasestransit, or until the collective pain of the outage or threat of litigation motivates the two networks to resumevoluntary peering. Lower tier ISPs and their customers may be unaffected by these partitionsbecause they may have redundant interconnections with more than one tier-1 provider. Frequentmisconceptions of the tier hierarchy include: Tier 1 networks are closer to the backbone of the Internet. In reality, tier 1 networks usually have only a small number of peers (typically only other tier 1 networks and very large tier 2 networks), while tier 2 networks are motivated to peer with many other tier 2 and end-user networks. Thus a tier 2 network with good peering is frequently much closer to most end users than a tier 1. Tier 1 networks by definition offer better quality Internet connectivity. By definition, there are networks which tier 1 networks have only one path to, and if they lose that path, they have no backup transit which preserves their continuous connectivity. Some tier 2 networks are significantly larger than some tier 1 networks, and are often a let provide more or better connectivity
27Broadband Remote Access Server (BRAS): A broadband remote access server(BRASB-RAS or BBRAS) routes traffic toandfrom broadband remote access devices such as digital subscriber line accessmultiplexers (DSLAM) on anInternet service providers (ISP) network. The BRAS sits at the core of an ISPs network, and aggregates user sessions from theaccess network. It is at the BRAS that an ISP can inject policy management and IP Quality of Service (QoS).The specific tasks include: Aggregates the circuits from one or more link access devices such as DSLAMs Provides layer 2 connectivity through either transparent bridging or PPP sessionsover Ethernet or ATM sessions Enforces quality of service (QoS) policies Provides layer 3 connectivity and routes IP traffic through an Internet service provider’s Back bone network to the Internet
28 A DSLAM collects data traffic from multiple subscribers into a centralized point so that it can be transported to a switch or router over a Frame Relay, ATM, or Ethernet connection. The router provides the logical network termination. The BRAS is also the interface to authentication, authorization and accounting systemsInternet Router: A router is a device that forwards data packets across computer networks. Routers performthe data "traffic directing" functions on the Internet. A router is connected to two or more data lines fromdifferent networks. When data comes in on one of the lines, the router reads the address information in thepacket to determine its ultimate destination. Then, using information in its routing table, it directs the packetto the next network on its journey or drops the packet. A data packet is typically passed from router to routerthrough the networks of the Internet until it gets to its destination computer unless the source IP is on a privatenetwork. The most familiar type of routers are home and small office routers that simply pass data,such as web pages and email, between the home computers and the owners cable or DSL modem, whichconnects to the Internet (ISP).In enterprises, a core router may provide a "collapsed backbone"interconnecting the distribution tier routers from multiple buildings of a campus, or large enterprise locations.They tend to be optimized for high bandwidthA typical home or small office router showing the ADSL telephone line and ETHERNETnetwork cable connections.
29Forwarding: The main purpose of a router is to connect multiple networks and forward packets destinedeither for its own networks or other networks. A router is considered a Layer 3 device because its primaryforwarding decision is based on the information in the Layer 3 IP packet, specifically the destination IPaddress. This process is known as routing. When each router receives a packet, it searches its routing table tofind the best match between the destination IP address of the packet and one of the network addresses in therouting table. Once a match is found, the packet is encapsulated in the Layer 2 data link frame for thatoutgoing interface. A router does not look into the actual data contents that the packet carries, but only at thelayer 3 addresses to make a forwarding decision, plus optionally other information in the header for hint on,for example, QoS. Once a packet is forwarded, the router does not retain any historical information about thepacket, but the forwarding action can be collected into the statistical data, if so configured. Forwarding decisions can involve decisions at layers other than layer 3. A function thatforwards based on layer 2 information, is properly called a bridge. This function is referred to as layer 2bridging, as the addresses it uses to forward the traffic are layer 2 addresses (e.g. MAC addresses onEthernet). Besides making decision as which interface a packet is forwarded to, which is handledprimarily via the routing table, a router also has to manage congestion, when packets arrive at ar ate higherthan the router can process. Three policies commonly used in the Internet are tail drop, random earlydetection (RED), and weighted random early detection (WRED). Tail drop is the simplest and most easilyimplemented; the router simply drops packets once the length of the queue exceeds the size of the buffers inthe router. RED probabilistically drops data grams early when the queue exceeds a pre-configured portion ofthe buffer, until a pre-determined max, when it becomes tail drop. WRED requires a weight on the averagequeue size to act upon when the traffic is about to exceed the pre-configured size, so that short bursts will nottrigger random drops. Another function a router performs is to decide which packet should be processed firstwhen multiple queues exist. This is managed through quality of service (QoS), which is critical when Voiceover IP is deployed, so that delays between packets do not exceed 150ms to maintain the quality of voiceconversations. Yet another function a router performs is called policy-based routing where special rules areconstructed to override the rules derived from the routing table when a packet forwarding decision is made.These functions may be performed through the same internal paths that the packets travel inside the router.
30Some of the functions may be performed through an application-specific integrated circuit (ASIC) to avoidoverhead caused by multiple CPU cycles, and others may have to be performed through the CPU as thesepackets need special attention that cannot be handled by an ASIC.Service control module: It is responsible for authentication and management of user access requests. It identifies legalusers. It can extract and record the statistics of user data packets and online duration for implementing thetraffic based or duration based accounting function. MA5200G sends the user’s accounting information to the RADIUS server. BRASallocates IP address through DHCP. It supports 4k to 96k IP addresses.MA5200G adopts packet bindingtechnology. After user passes authentication It checks the binding relation of the IP address, MAC address,logical port and PPPoE session ID in each packet of this user and the packets that do not match will bediscarded.Wi-Fi:Wireless Technology is an alternative to wired Technology for connecting the devices in wireless mode. Wi-Fi refers to the IEEE 802.11 communication standard for wireless LAN. Wi-Fi network connect computersto each other to the internet and to the other wired networks. Wi-Fi networks use Radio Technologies totransmit & receive date at high speeds.Wi MAX: Wi MAX (Worldwide Interoperability for Microwave Access) is a telecommunicationsprotocol that provides fixed and mobile Internet access. The current Wi MAX revision provides up to 40 Mbit/s with the IEEE 802.16m update expected to offer up to 1 G bit/s fixed speeds. The name "Wi-MAX"was created by the Wi MAX Forum, which was formed in June 2001to promote conformity andinteroperability of the standard. The forum describes Wi MAX as "a standards-based technology enabling thedelivery of last mile wireless broadband access as an alternative to cable.
31Comparison between Wi-Fi and Wi-MAX: Comparisons and confusion between Wi MAX and Wi-Fi are frequent because both are related to wireless connectivity and Internet access. Wi MAX is a long range system, covering many kilometers that uses licensed or unlicensed spectrum to deliver connection to a network, in most cases the Internet whereas Wi-Fi uses unlicensed spectrum to provide access to a local network. Wi-Fi runs on the Media Access Controls CSMA/CA protocol, which is connectionless and contention based, whereas Wi MAX runs a connection-oriented MAC. Wi MAX and Wi-Fi have quite different quality of service (QoS) mechanisms. WiMAX uses a QoS mechanism based on connections between the base station and the user device. Each connection is based on specific scheduling algorithmsAdvantages of Broadband: Connection speed is up to 100 times faster than dialup connection. You can download pictures files, software in seconds or minutes instead of hours. Online gaming is only possible using a broadband internet access. It does not affect the phone line. For DSL internet access, you can use the same phone line for both voice/fax and data transmission. For cable internet access, you are connected to the internet via the cable network. In either case, your phone line is not occupied while you are connected to the internet It is convenient because the internet connection is always on. You dont need to dial an access number and risk getting a busy signal. Broadband internet offers unlimited access and you wont be charged based on the connection duration.
32 Broadband internet not only gives you high speed internet access, it can also provide cheap phone services via VoIP technology.Disadvantages of Broadband: High monthly fee compared to dialup internet access. Higher security risk than dialup connection. A personal firewall is needed to protect your computer. Not all phone wires are equipped for DSL service. Not all cable TV networks are equipped for cable internet access. May not be available in rural or remote areas.Applications:In telecommunication: Broadband in telecommunications refers to a signaling method that includes or handles arelatively wide range (or band) of frequencies, which may be divided into channels or frequency bins. Thewider the bandwidth of a channel, the greater the information-carrying capacity.Telemedicine enables health care professionals and patients to take advantage of digital communications tosave money, time, and travel and most importantly, improve the quality of care.Teleworking or telecommuting is working from home or outside the traditional office or workplaceusing a digital device and an Internet connection. Telework benefits employerswho see savings in
33Information Gathering: More and more people are using the Internet to gather information for anything from medicalinformation to job searching and news and information and shopping.Tourism: Broadband and community content allow people to find out what is available in touristdestinations and also helps people to see events or exhibits they might otherwise never be able to visit inperson.Entertainment: Many people use the Internet for fun, to play games, gamble, download movies, music, TVshows, books or information and services. As technology advances the applications and opportunities for e-commerce and entertainment expand exponentially Office overhead costs as well as increased productivityand motivation of their employees.E-Government: refers to the increasing push for government at all levels to make more services availableonline. Local governments use e-Government to deliver services and information to their residents andcustomers 24 hours a day, seven days a week.Public Safety: Broadband networks can assist police, fire and other law enforcement personnel in manycrisis situations.National Security: Broadband can be used by national, state and local authorities for surveillance,videoconferencing, data mining, pattern matching and other applications to assist law enforcement andmedical services.
34 CONCLUSIONI have learned about the broadband internet connectivity using the dsl connections, wificonnectivity and internet through land phones, Problems persisting while connecting theinternet, new technologies about wi-max and remote access servicing at bsnlsanchar bhavan.Reference:By Using internet and TSSN textbook.