Broadening your network horizons

For a long time the plain old public telephone network was used to carry data. A liberalized telecom environment, availability of bandwidth, falling prices for telecom services, the Internet and the IP-based network phenomenon have dictated the network choices in the past few years.

The Indian Broadband Report Card

According to IDC’s recent report "ADSL Network and CPE Market Forecast & Analysis, 2001-2006", IDC estimates that by 2006, the overall ADSL equipment market in the region will be $963.2 mn, representing a CAGR (2001-2006) of only 1%. Of this total, ADSL modem CPEs will generate revenue of $409.6 mn and DSLAM lines will show revenues of $553.6 million.

Although there are a variety of access technologies available in Asia/Pacific, including ADSL, cable modem access, metro Ethernet, and FWA, ADSL remains the preferred medium. In 2001, about 65% of all broadband subscribers in the region used ADSL. On the network equipment side, the number of DSLAM lines shipped in 2001 totalled over 5.8 mn, showing a year on year increase of over 103%.

However, while lines shipped actually showed a substantial increase, revenue generated declined to about $696 mn, a fall of 18%. The reason for this is that during the year, there was a large fall in DSLAM line ASPs region-wide, and particularly in large and key markets.

The equipment market is becoming increasingly competitive in the region, as domestic vendors, are driving down ASPs in their respective countries. Throughout the region, it is anticipated that ADSL equipment ASPs will continue to decline during the forecast period.

During this time, private sector companies started building networks that spanned the length and breadth of the country. These purportedly would engage in providing network services for corporate India with promises of speed, bandwidth, security, quality of service, scalability, and reliability.

Still, enterprises find it increasingly difficult to choose the right options for networking. Especially so, with terms like convergence, broadband, wireless, VPN, 2.5G, 3G, CDMA, DWDM being the order of the day, while networks continue to evolve rapidly.

Making the right choices today with a view of the network of the future would actually save money for these companies. Access technologies being at the periphery of the network and directly connecting to the organization are the most crucial.

Increasingly, the trend is that companies would not need to build their own networks, but they will have to create networks for themselves from the available access providers and network operators or together known as network service providers (NSPs). The choices of access that delivers higher bandwidth (call it broadband) are many–DSL, cable, fixed wireless, satellite wireless, or optical Ethernet.

Enterprises must first define their broadband access needs and then select the most appropriate services. The key consideration is to determine the applications supported and their underlying bandwidth, latency, and availability requirements.

DSL (Digital Subscriber Line) is a technology for bringing high-bandwidth information to homes and small businesses over ordinary copper telephone lines. Digital Subscriber Line is a technology that assumes digital data does not require change into analog form and back.

Digital data is transmitted to your computer directly as digital data and this allows the phone company to use a much wider bandwidth for transmitting it to you. Meanwhile, if you choose, the signal can be separated so that some of the bandwidth is used to transmit an analog signal so that you can use your telephone and computer on the same line and at the same time. ADSL line can carry both data and voice signals and the data part of the line is continuously connected.

ADSL is called "asymmetric" because most of its two-way or duplex bandwidth is devoted to the downstream direction, sending data to the user. Only a small portion of bandwidth is available for upstream or user-interaction messages.

However, most Internet and especially graphics- or multi-media intensive Web data need lots of downstream bandwidth, but user requests and responses are small and require little upstream bandwidth. Using ADSL, up to 6.1 megabits per second of data can be sent downstream and up to 640 Kbps upstream.

The high downstream bandwidth means that your telephone line will be able to bring motion video, audio, and 3-D images to your computer or hooked-in TV set. In addition, a small portion of the downstream bandwidth can be devoted to voice rather data, and you can hold phone conversations without requiring a separate line.

Cable TV’s transmission medium–coaxial cable and fiber optics–supports much higher data rates than do phone lines. However, there are no dedicated connections. Up to 600 subscribers may share the cable bandwidth in a neighbourhood. Cable TV’s shared transmission medium highlights the chief difference between DSL and cable.

A dedicated DSL access connection can readily guarantee data or throughput rate. Cable access, however, is shared among a large number of users, which makes guaranteed data levels harder to attain. Cable’s shared design also raises data security issues. However, cable can attain higher data rates (typically four times faster) for a given price point than DSL.

A number of techniques, such as remote terminals and next-generation DSL technologies, will reduce problems associated with distance limitations; however, DSL will remain limited to the low multimegabit data rate range. The other option is to have optical fiber-based Ethernet especially in metros and large cities. With optical fiber already in place, they are delivered into the customer’s premises in Ethernet-mode.

Satellite services (using VSATs) may be appropriate where other broadband alternatives are unavailable or for large branch or retail networks in which low cost is more critical than throughput. Today’s satellite services have limited capability; uplink data rates top out at 384 Kbps and downlink rates top out at 4 Mbps. Because multiple sites share satellites, less than 10% of the maximum data transmission rates are typically available to a specific site.

There are also terrestrial fixed wireless systems that can be used for broadband access; these require a small antenna in line of sight to the NSP. Where available, multipoint multichannel distribution service (MMDS) or local multipoint distribution service (LMDS) may be less than half the cost of business-grade DSL service.

MMDS offers burst rates of up to 5 Mbps, with average speeds between 1 and 2 Mbps, and is thus positioned to compete against DSL and cable modem technology.

The wireless area is getting even more exciting. Third-generation technologies such as wideband–CDMA are fast becoming popular even while 2.5G networks improve. In the midst of all this, the wireless LAN phenomenon is interesting. Wireless LANs based on IEEE 802.11a,b, also known as WiFi are sort of edging out or at least delaying growth for 3G.

The bottomline is that for most of the mid to large organizations a single access method won’t suffice–a judicious combinations usually works best. Broadband access is the key driver for virtual private networks (VPNs). The intense interest in VPNs is fuelled by the trend of networks extending beyond the enterprise as necessitated by mission-critical next generation enterprise applications like ERP II. For VPNs to become more mainstream, low-cost, affordable, high-bandwidth, always-on connectivity is required.

Such broadband access using technologies other than private lines is becoming a reality. A well-defined VPN serves as an open network that is sufficient to meet the needs of the enterprise but is cheaper to implement and easier to deploy than legacy networks.

The biggest appeal of VPNs is that it can ride on the public Internet. But in a few years, the Internet will not be able to provide service levels for a majority of enterprise apps. This will require moving over to new IP-based networks. These would be called enhanced IP services.

One such service is called Multiprotocol Label Switching (MPLS). According to the Gartner Group, "By 2010, a single advanced IP network will handle most of the world’s communication needs". The emerging network will extend well beyond voice, data, and local and long distance; it will support an ever-widening array of services.