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© Tech Mahindra Limited 2011 © Tech Mahindra Limited 2010

Comparison of BroadbandConnections:

DSL with Cable

A whitepaper

By

Ankur Rawat

&

Sasindran M Prabhu

Feb, 2011

Abstract:

Unless a user live or work in a remote or veryrural area, he probably have the option of giving up the slow dial-up modem and investin a broadband Internet connection. If high-speed Internet services are available, user hasoptions like DSL (Digital Subscriber Line) andcable modem services. Both DSL and cablemodems are common home networkingbroadband connection technologies - but

hich option is better?

This paper provides an overview of DSL &Cable along with the competitive analysis of both the technologies from technical,availability, security & price point of view.



1

© Tech Mahindra Limited 2011

Table of Contents

What is DSL internet connection………………………….3

What is Cable internet connection………………………..5

DSL Vs Cable……………………….………………………….7

Conclusion………………………………………………………12

Tech Mahindra‘s Plan………………………………………..13

List of figures & tables……………………………………....14

References.................................................................15



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Acronyms & Abbreviations

CMTS Cable Modem Termination System

DOCSIS Data Over Cable Service Interface Specification

DSL Digital Subscriber Line

FTTx Fiber to x. ―x‖ could be Building, Home, Premises or Network

IP Internet Protocol

MCNS Multimedia Cable Network System

SLA Service Level Agreement

QoS Quality Of Service

TCP Transport Control Protocol

UDP User Datagram Protocol



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What Is DSL Internet Connection?

Digital Subscriber L ine (DSL) is a technology that provides digital datatransmission over the existing wires of local telephone network. DSL service isdelivered simultaneously with regular telephone on the same telephone line. Thisis possible because DSL uses a higher frequency. These frequency bands aresubsequently separated by filtering. Figure 1 shows the basic DSL networktopology.

Figure 1: Basic DSL network diagram

DSL uses a sophisticated modulation scheme to pack data onto the existing

copper wires. DSL is sometimes referred to as the last-mile technology since it isused mainly for connections from a telephone switching station to a home oroffice. DSL is also called an ―always on‖ connection since it uses existing 2-wirecopper telephone line connected to the premise and will not tie up your phone as adial-up connection does. There is no need to dial in to your ISP as DSL is alwayson.

http://en.wikipedia.org/wiki/Digital

http://en.wikipedia.org/wiki/Access_network

http://en.wikipedia.org/wiki/Plain_Old_Telephone_Service

http://en.wikipedia.org/wiki/Telephone_line

http://www.webopedia.com/TERM/X/xDSL.html

http://www.webopedia.com/TERM/I/ISP.html

http://www.webopedia.com/TERM/I/ISP.html

http://www.webopedia.com/TERM/X/xDSL.html

http://en.wikipedia.org/wiki/Telephone_line

http://en.wikipedia.org/wiki/Plain_Old_Telephone_Service

http://en.wikipedia.org/wiki/Access_network

http://en.wikipedia.org/wiki/Digital



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The two main categories of DSL for home subscribers are called ADSL and SDSL. Table 1 shows the comparison of different flavors of DSL.

Table 1: Comparative study of different DSL flavors



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What Is a Cable Internet Connection?

Cable internet connection is an internet connection designed to operate overexisting cable TV lines. Cable Internet access requires a Cable Modem (CM) at thecustomer's premises and a Cable Modem Termination S ystem (CMTS) at a cableoperator facility. The two are connected via coaxial cable because the coaxial cableused by cable TV provides much greater bandwidth than telephone lines. CableInternet systems can typically operate where the distance between the modem andthe termination system is up to 100 miles (160 km). Figure 2 shows the basicCable TV and Internet topology.

Figure 2: Basic Cable network diagram

http://en.wikipedia.org/wiki/Cable_modem





http://en.wikipedia.org/wiki/Cable_modem_termination_system








http://en.wikipedia.org/wiki/Multi_system_operator


http://en.wikipedia.org/wiki/Coaxial_cable

http://www.webopedia.com/TERM/C/coaxial_cable.html

http://www.webopedia.com/TERM/C/coaxial_cable.html

http://en.wikipedia.org/wiki/Coaxial_cable







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Traditional Cable Television (CATV) provides a unidirectional transport of videochannels to home consumers. Competition from satellite TV providers forced thedevelopment of a full-duplex data infrastructure, across a Hybrid Fiber/Coaxial

(HFC) network. Open-standard specifications for data communication across thisBroadband Cable network are defined by the Data Over Cable Service InterfaceSpecification (DOCSIS). DOCSIS was developed by the Multimedia Cable NetworkS ystem (MCNS) Partners (now CableLabs), and defines the Layer-1 and Layer-2specifications for cable communication.

There are four current implementations of this specification and there comparisonis shown in Table 2:

• DOCSIS v1.0

• DOCSIS v1.1

• DOCSIS v2.0

• DOCSIS v3.0

Table 2: Comparative study of different DOCSIS versions



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DSL Vs Cable

We have basically compared DSL and Cable on four grounds, namely availability,speeds, security and price.

1. Availability

DSL was first designed in the 1970‘s whereas Cable‘s HFC was designed in the‗80s and ‗90s. Roughly 80 to 85 percent of America's 68 million cable TVsubscribers (say, 55 million or so) can get high-speed access, says Instat-MDRanalyst Mike Paxton. DSL access is a little spottier, though Instat's ErnieBergstrom puts the number above 50 million. In terms of worldwide broadbandmarket share, currently DSL has higher market share compared to Cable but incoming years picture may change. Figure 3 shows the broadband market share bydifferent technologies.

Figure 3: Worldwide Broadband Market Share (Source: Point Topic research)



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2. The Speeds

The topic of "which is better and faster" has been a highly debated topic, and stillthere doesn't appear to be a clear winner. DSL offers users a choice of speedsranging from 144 Kbps to 1.5Mbps. Cable modem download speeds are typicallyup to 2 times faster than 1.5Mbps DSL, but the reason there is no clear speed winner is because cable technology is based on shared bandwidth, with manyfactors influencing a user‘s download speed. With shared bandwidth the speedfluctuates depending on the number of subscribers on the network. With DSL, theconnection is kind of dedicated and not shared, and user gets more or less aninvariable speed. This is one reason why cable broadband providers don't oftenpublish speed information. In more rural areas with fewer subscribers, usersbound to have faster download speeds than a user in a metropolitan center.

Because cable modem speeds fluctuate, it is difficult to gauge an exact downloadspeed. On the upload stream, however, cable and DSL are closely matched forspeed. Both DSL and cable Internet speeds are largely dependent on the serviceprovider and either the distance away from the switching station a user is or howmany users are in an immediate area.

Figure 4 shows the internet speed offered by different ISP‘s over different mediumslike Optical, Cable & DSL.

Figure 4: Internet speed over different mediums like Optical, Cable & DSL



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3. Home Networking & Security

Both DSL and Cable Internet can easily be shared with computers on home LAN

through software (Microsoft Internet Connection Sharing for example) or by usinga connection sharing device, such as a router and firewall software. Using a SOHOrouter is most-often the recommended option as this will also provide a muchneeded firewall protection for users LAN as well. It is always advisable to check with the service provider, as sharing the broadband connection may violate Termsof Service agreement. In many areas, service providers usually allow the user toconnect additional computers to a single your broadband internet connection for anominal fee. Because Cable is shared connection, users are actually sharing thebandwidth with other users in the same area. This would really create securityissues only if no security measures are in place, but cable service providersgenerally provide cable modems with security features in the hardware. Overall

the security of these broadband connections are closely matched, with DSL boasting a bit better security — and it is always advisable to consider purchasingadditional hardware or software to protect your system, as the service providermay only provide the basics with the installation & set-up of the internetconnection.

4. The Price

The price users will pay for DSL or cable Internet services is not standard. Itdepends on how much competition there is for broadband services, and the area you live in. For example, in some areas it's only been in the past few years thatcable Internet has been available. Until then, DSL costs were quite high, but ascable Internet became available the price of DSL went down. With either option, you generally will pay a one-time set-up fee. For cable, you could expect this fee tobe anywhere from $50 to $100, while the cost for DSL installation is a bit moreand could run up to $150 for set-up. Once the installation is completed, you willusually pay for your Internet subscription on a monthly basis. Cable, again, isusually a bit cheaper with monthly fees averaging $40 to $50. You can expect topay about $5 to $10 more a month for DSL service.

According to “Broadband Tariff Benchmark report for Q3 2010” by ―Point Topic‖, the worldwide entry level broadband services by technology. The averagecosts are at their most similar totaling USD 27.42 for DSL, USD 29.25 for cablemodem and USD 33.44 for FTTx. Average costs of DSL and cable modem haveincreased very gradually since December 2009, there was a fall in the average costfor FTTx from March 2010 to June 2010. Figure 5 shows the above mentionedillustration.

http://www.webopedia.com/TERM/I/ICS.html

http://www.webopedia.com/TERM/R/router.html

http://www.webopedia.com/TERM/F/firewall.html

http://www.webopedia.com/TERM/S/SOHO.html

http://www.webopedia.com/TERM/S/SOHO.html

http://www.webopedia.com/TERM/F/firewall.html

http://www.webopedia.com/TERM/R/router.html

http://www.webopedia.com/TERM/I/ICS.html



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Figure 5: Average Entry Level Broadband Service Tariff (Source: Point Topic)

If a user lives in an area where both cable and DSL are available then he may findhimself being able to nab a better broadband service deal. Local DSL or cablecarrier may offer introductory offers such as free installation or offer the Internetservice free for a couple of months. In addition, user can also check and see if theservice provider offers discounts on service bundles. For example, many cable

companies offer discounts for "surf and watch" which comes with a price discountif a user subscribes to both cable TV and cable Internet service from the sameprovider (also many cable operators now offer VoIP capabilities as part of the mix).

If a user chooses DSL, he may qualify for a "surf and talk" bundle plan. If a user isnot already a broadband subscriber, he can save money by checking with localservice providers and signing up for a broadband account.

According to “Broadband Tariff Benchmark report for Q3 2010” by “PointTopic”, Broadband using fiber technology offers the cheapest price per megabit.However, it is important to note that this is based on the maximum speedsavailable according to the tariffs advertised. Whether or not these speeds areactually attained remains to be a debatable topic. Cable modem offers the nextcheapest cost per megabit in all regions and DSL is the most expensive.



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Figure 6 shows that both FTTx and cable modem offer a similar cost per megabit when compared to DSL. This disparity is mainly due to the extremely high speedsthat can be attained using both FTTx and cable modem. In terms of speeds, cable

modem was mid ranged between DSL and FTTx. However, now that many cableoperators are upgrading their networks using technologies such as DOCSIS 3.0much faster speeds can be attained which are comparable with those speedsattained using FTTx. In Asia Pacific, operators are heavily promoting FTTxservices. This can be seen by the relative costs per megabit in this area. This isone of the few areas where the cost per megabit of FTTx services is much smallercompared with DSL and cable modem. Eastern Europe also has a low cost permegabit for FTTx services, but the cable modem services in this region are thelowest per megabit overall. This is mainly due to the influence of UPC subsidiarycompanies, which offer low cost high speed services in a number of countries in

the region.

Figure 6: Price per Megabit by technology and region for residential services

(Source: Point Topic)



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Conclusion

After in-depth analysis of DSL and Cable internet, we can conclude that CableInternet wins over DSL in terms of price and speed but this point holds valid fordeveloped countries like US where already many DSL and Cable Service providershave established there market. At the same time, situation in developing countrieslike India is bit different. In such countries, telephone operators have strongerpresence compared to Cable TV service providers. So, DSL service providersobviously have better subscriber base compared to Cable Internet providers butthinks can change in future.



13


Tech Mahindra’s Plan

Based on the Capabilities in Cable, DOCSIS, IPTV & broadband technologies, TechMahindra will be able to contribute in the following areas. Based on the marketpotential and the opportunities from the vendors, we will be able to select a fewamong these areas.

DOCSIS featuresIPTV featuresQoS featuresOAM moduleEMS/NMS module

Based on the opportunity from the vendors, we will be able to select among theseactivities:

Requirement AnalysisProduct Design & Development Testing & ValidationInteroperability TestingNetwork Design, Deployment & Maintenance for Telecom Service Providers.



14


List of Figures & Tables

Figures:

Fig 1 – Basic DSL network diagramFig 2 – Basic Cable network diagramFig 3 – Worldwide Broadband Market ShareFig 4 – Internet speed over different mediums like Optical, Cable & DSL Fig 5 – Average Entry Level Broadband Service Tariff Fig 6 – Price per Megabit by technology and region for residential services

Tables:

Table 1 – Comparative study of different DSL flavors Table 2 – Comparative study of different DOCSIS version



15

References

DOCSIS webpage on www.wikipedia.orgDSL webpage on www.wikipedia.org―Broadband tariff‖ report for Q3 2010 by ―Point Topic‖ www.metroethernetforum.org www.cablelabs.com

http://www.wikipedia.org/


http://www.metroethernetforum.org/

http://www.cablelabs.com/

http://www.cablelabs.com/

http://www.metroethernetforum.org/



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