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Issue of January 2005 

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Wan Connectivity

WAN gives an edge

Companies that share information across locations and personnel in the most efficient manner have a competitive edge over others. This makes a reliable and scalable WAN essential. by Soutiman Das Gupta

The rising adoption of enterprise applications such as ERP, SCM, CRM and databases along with the growth of customers, geogra-phical locations, business units, sales personnel and business executives has made a nationwide enterprise WAN, or a connectivity backbone a necessity for Indian enterprises.

So let us take a look at the enterprise WAN connectivity measures that are in use today and the various technologies that can help create a more efficient and reliable WAN.

Wireline in the WAN

Traditionally the leased line has been the preferred mode of wireline connectivity between company locations in different cities. The primary reason for the popularity of this technology is that there was no alternative in terms of wireline broadband wide area connectivity until recent times.

Leased lines are typically 64 or 128 Kbps links going up to E1 and beyond. These services are mostly provided by telcos and these lines are customarily backed up by ISDN links.

In many cases companies find that leased lines offer lower reliability and QoS, insufficient scope for monitoring and management, and too low a minimum guarantee of bandwidth.

Changed scenario

The scene has changed and the entry of private players such as Bharti Tele-Ventures Limited, Reliance Infocomm Limited, Sify, and Cable & Wireless in the market has lead to a dramatic upsurge in the kind of choices that enterprises have in terms of the number of service options that they can choose from including QoS, enhanced service quality, support for voice and video, bandwidth-on-demand,VPNs, managed security, and remote monitoring.

The cost of connectivity has also come down and an enterprise now has a number of flexible payment options where a few services are bundled together as a package, and a company can pay as it uses these services.

"Earlier telcos would offer a basic point-to-point link between two locations. But now the needs have evolved from a one-to-one link to a many-to-many infrastructure. This is because an enterprise now has extended connectivity to a number of entities in its value chain such as its suppliers, customers, retailers, distributors, and internal personnel on the move," says Rahul Swarup, President, Enterprise Solutions Division, Sify Limited.

An RF in the MAN

Exel India Private Limited (EIPL), a logistics solutions provider, was looking for a reliable technology to connect its offices in Mumbai. It found leased lines unreliable and inflexible for its need and had to ensure always-on communication between its central and operations offices. The company eventually opted for RF-based (Radio Frequency) wireless links to connect its six locations in Mumbai

EIPL had installed a 2 Mbps leased line between its Mumbai offices, which were within a radius of five km from the central office. Although the leased line was backed up by an ISDN link, the company felt that the solution was not very useful as it took a very long time to implement, offered unreliable connectivity, and erratic customer service.

After conducting a wireless line-of-sight survey the company, deployed RF links between the offices. The company is so satisfied with the performance of the RF links that it now uses the leased lines as secondary links, and ISDN as backup for those.

The ideal wireline WAN

In order to create the ideal WAN, an enterprise has two choices. Build and manage the infrastructure in-house, or outsource it.

A home-grown WAN infra-structure will typically consist of a backbone of single mode optic fibre that connects various locations nationwide. The infrastructure must terminate at routers with optic fibre converters, and must have signal amplifiers at strategic locations in between links.

The Konkan Railway Corporation has installed 700 km of optic fibre to connect a number of railway stations and administrative units along its train route in western India.

BSNL has 27,000 rural exchanges, which have optical fibre connectivity in all the 2,648 Short Distance Charging Areas (SDCAs) making the optical fibre nodes available in four to five interior locations in each block.

Outsource the WAN

The other option is to outsource wide area connectivity. This usually turns out to be cost-effective and hassle free. The current trend is to use several service providers in order to exploit the best capabilities of each, and have a single-window entity for management, trouble-shooting, and payment.

For instance, if an organization wants to connect its offices in Mumbai and New Delhi it can use the last mile infrastructure of a local service provider (MTNL, Hughes, and Tata Power in both cities). A National Long Distance (NLD) service provider such as Reliance, Bharti, and VSNL can provide the long-range backhaul between any two cities.

An organization can use a single service provider entity for all it's management, monitoring and billing needs, and possibly a third party NOC that will manage and monitor its WAN, and provide services like VPN, video-on-demand and managed security.

A data speed record

A group of researchers have been able to transfer huge amounts of data at a sustained rate of 101 Gbps. The team sustained the 101-gigabit speed for only a few minutes during the 90-minute demonstration, peaking at just above the 101-gigabit mark.

The data transfer rates were achieved in part though the Fast TCP protocol developed by Caltech professor Steven Low, which prevents congestion better than standard TCP. Standard TCP gauges congestion by the rate that packets of data get dropped. FAST TCP observes the delay that packets experience as they travel through the network.

A 'High Energy Physics' team performed the feat and won the Supercomputing Bandwidth Challenge, a contest geared toward improving network connection speeds for grid computing. The team includes computer scientists, physicists and network engineers from Caltech, Fermilab, CERN, the University of Manchester, and universities from Korea and Brazil.

Mixing it up

"The way ahead for wireline WAN connectivity is that companies will move to a mix of public and private networks,” says Swarup. "Companies will move to the use of MPLS-based VPNs in order to exploit the large reach and cost-efficiency of a public network," adds SB Patankar, Director, Information Systems, The Stock Exchange.

Since MultiProtocol Label Switching (MPLS) creates 'virtual circuits' or tunnels, across an IP network, service providers use MPLS to provision VPN services. Several standards have been proposed to allow for VPN services that isolate a customer’s traffic across the provider's IP network and provide secure end-to-end connectivity.

MPLS provides a great deal of flexibility to divert and route traffic around link failures, and bottlenecks. From a QoS standpoint, ISPs will be able to manage different kinds of data streams based on the priority and service plan.

However, MPLS simply provides traffic isolation, much like an ATM or Frame Relay service. MPLS currently has no mechanism for packet encryption, so if an enterprise requires a high level of security it must use IPsec or other related standards.

Users of these technologies include UCO Bank (IP-VPN), and the Oriental Insurance Company Limited (MPLS-based).

"India is experiencing convergence with enterprises investing in intelligent networking solutions. IP-Telephony, network security, wireless networking, and storage networking are significant new technologies that are being accepted by the industry. These are riding on reliable and efficient, high-speed core networks with MPLS and optical networks, says Devendra Kamtekar - Principal Consultant - Cisco Systems.

"In developed countries such as the USA, companies have almost stopped outsourcing their data connectivity needs to a traditional telco. They engage the services of a Value-added Service Provider who can provide services to make the connectivity experience more reliable and business-friendly. So the decision to use a service provider is based upon the value provided rather than on connectivity," says Shivaji Chatterjee, Director, Sales and Marketing, Hughes Escorts Communications Ltd.

Lower tariffs ahead

Competition among broadband service providers is expected to lead to lower leased line tariffs over the next few months as per a consultation paper of the Telecom Regulatory Authority of India (TRAI). The costs of 2 Mbps and 64 Kbps links may plummet by around 60 percent.

You can download the consultation paper from:

Long-haul wireless

Many companies in India have offices located in remote areas and smaller towns where reliable telecom and connectivity infrastructure are not always available. In such cases, a wireless solution can be a viable option. Wireless links provide sufficient bandwidth (even near E1 capacity), can be set up very quickly, have little downtime, and are easier to manage and monitor than leased lines. The ground does not have to be dug up, special permits or licenses to lay cabling infrastructure, and expensive cabling is not required.

The various wireless connectivity means in the WAN are vSATs, Wi-Fi, WiMax, CDMA, GSM, LMDS and Radio Frequency (RF).

The VSAT alternative

A Very Small Aperture Terminal (VSAT) is used to receive and transmit information with the help of terminals installed at dispersed sites connecting to a central hub via satellite using small diameter dish antennas (0.6 to 3.8 metres).

VSAT network topologies include point-to-point, point-to-multipoint, and on-demand.

"A cost comparison between a VSAT service and its terrestrial equivalent is difficult because wireline services charge by distance. VSATs cost the same regardless of the location," says CS Raghava Rao, GM - OTSS and Technical Services, Comsat Max Limited.

Indoor and Outdoor Units at the company's site are required to get connected to a VSAT network. The waiting period is between two and three weeks. VSATs generally operate in the Ku-band and C-band frequencies. Ku-band based networks, are used primarily in Europe and North America and utilize smaller VSAT antennas. The C-band, which is used extensively in Asia, Africa and Latin America, requires a larger antenna.

VSATs continue to be reliable and scalable means of long distance communication for enterprises. "However, the road ahead will be about licenses and service levels and not so much about technology development,” says Chatterjee.


802.11x technologies can be used to build reliable point-to-point connectivity in the WAN. The use of bi-directional antennas and wireless bridges can be used to maintain signal strength.

Sumul Dairy, headquartered in Surat has a presence at three remote locations. They are Navi Pardi at a distance of 16 kms, Chalthan factory at a distance of 13 kms, and Bajipura at a distance of 33 kms from Chalthan.

As laying fibre optic links to extend the network over such a long distance did not seem practical, and therefore it deployed wireless outdoor access points and 23dBi Parabolic Grid antennae to connect its dispersed locations.

To enable security, the company uses 128-bit encryption, anti-Denial of Service infrastructure, NAT firewalls, Mac address-based access control, and password authentication. These measures are the usual and most effective means of ensuring security over a Wi-Fi link since the prevailing standard WEP still has a few issues that need to be worked out.


The Worldwide Interoperability for Microwave Access (WiMax) standard 802.16-2004 (formerly known as 802.16d) is the new baseline standard for WiMAX. It was ratified in June 2004.

The technology has a linear range of up to 31 miles and allows user connectivity without direct line of sight to a base station. It provides shared data rates up to 70 Mbps and can simul-taneously support more than 45 businesses with T1-equivalent connectivity.

There are not too many manufacturers of WiMax hardware and the equipment is mostly proprietary in nature. This is a blow to interoperability and may be a hindrance to rapid roll-outs of this technology.

These are expected to be ironed out soon since the WiMax forum is increasing the number of member companies within its fold, and relevant issues are being sorted out.

The Indian Railways has begun to use WiMax on an experimental basis.


Code Division Multiple Access (CDMA) is a technology that competes with GSM for dominance in the cellular world.

We currently have cdma2000 and its variants such as 1X EV, 1XEV-DO, and MC 3X.

This first phase of cdma2000 (1XRTT, 3G1X, or just plain 1X) is designed to double current voice capacity and support always-on data transmission speeds 10 times faster than what is typically available today, which works out to 153.6 Kbps on both the forward and reverse links

Although this technology is used more for personal mobile communications, it has a lot of use in enterprises as well. A number of Indian Banks including SBI and UTI use CDMA-based networks for connecting the ATMs on their WANs.

Reliance Logistics uses CDMA-based technology to perform GIS mapping for its nationwide fleet of trucks. Each truck is fitted with a GIS unit, which sends homing signals every time it enters an Indian city, which has CDMA telecom services whereupon Reliance Logistics and its clients are sent SMS messages.

A structured WAN

The South Central Railway (SCR) in association with the Govt. of Andhra Pradesh will deploy a Multi-Modal Transport System (MMTS) using fibre and UTP structured cabling infrastructure.

The project involves the setting up of Self Printing Ticketing Machines (SPTMs) in 25 railway stations by the SCR connected by a structured WAN. It covers the Falaknuma-Secunderabad-Hyderabad-Lingampally stretch, including those at the tourist destination of Hussain Sagar lake in the heart of Hyderabad, the busy Lakdi Ka Pul and HITEC City, which houses global and national IT giants.

The project aims to reduce vehicular congestion and offer a faster, cleaner and greener mode of transport to residents of the twin cities of Hyderabad and Secunderabad. D-Link India Limited is the cabling solution provider.

Wireless in education

The Indian Institute of Information Technology, Bangalore (IIIT-B) has set up a WLAN at its Bangalore campus, which covers 75,000 square feet.

The earlier network was based on Cat 5e, managed switches, and hubs. It had a high rate of data collision resulting in the loss of valuable data. The network had no scope for upgradation and it provided no mobility to the users.

Access points from D-Link India Limited were spread across the campus supported by a Fast Ethernet backbone on a copper interface that connected to the wired LAN. DHCP configuration was used in the Wi-Fi network to give Internet access to any new mobile user. The wireless network can be centrally managed from a single location.


Global System for Mobile Communications (GSM) uses narrowband TDMA technology. It can be used as a point-to-point technology to connect remote locations. Although it's widely used for personal communications, GSM's use in the enterprise is infrequent.

LMDS and Radio Frequency

LMDS is a broadband wireless point-to-multipoint communication system operating above 20 GHz (depending on country of licensing) that can be used to create point-to-point fixed wireless networks.

It can be deployed to offer high-speed dedicated links between high-density nodes on a network. It provides an effective last-mile solution for an incumbent service provider and can be used by competitive service providers to directly deliver services to end users.

The use of point-to-point line-of-sight Radio Frequency (RF) links between company locations is a useful alternative to running expensive optic fibre cables.

LMDS and RF technologies can be used in the WAN and MAN as an alternative to VSATs.

Keeping the MAN Connected

A Metropolitan Area Network (MAN) usually covers all enterprise locations in an entire metropolitan area, such as a large city and its suburbs. MAN technology was typically based on FDDI, and data rates ran from 64 Kbps to T3 speeds (45 Mbps).

Wireline connectivity in the MAN was typically provided by the incumbent operators, but with deregulation and liberalization, new private carriers began to compete with the incumbent operators by offering specialized data services based on SDH/SONET backbones.

The concept of a city-based MAN is that it should support both voice and Internet/IP service applications for the enterprise. The use of Ethernet in the last mile and an optic fibre backbone is a preferred combination.

Enterprises can also use VSATs, Radio Frequency (RF), and microwave links to create point-to-point connectivity mechanisms.

The Bombay Municipal Corporation (BMC) has connected between 30 and 40 water pumping stations around Mumbai with VSAT links for sharing information.

Soutiman Das Gupta can be reached at:

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