WAN gives an edge

The rising adoption of enterprise applications such as ERP, SCM, CRM and databases along with the growth of customers, geographical 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 ofwireline 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 the 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 Ltd., Reliance Infocomm, Sify Ltd, and Cable and Wireless in the market has led to a dramatic upsurge in the kind of choices that enterprises have in terms 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 many-to-many infrastructure. This is because an enterprise now has extended connectivity to a number of entities in its value chain such as suppliers, customers, retailers, distributors, and internal personnel on the move," says Rahul Swarup, President, Enterprise Solutions Division, Sify Ltd.

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 infrastructure 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 convertors, and must have signal amplifiers at strategic locations in-between links.

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, 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 Tele.com, and Tata Power in both cities) A National Long Distance (NLD) service provides such as Relience, Bharti, and VSNL can provide the long-range backhaul between any two cities.

An organization can use a single service provider entity for all its 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

Making IT UP

"The way ahead for wireline WAN connectivity is that companies will move to a mix of public and private networks," says Swarup

Since MultiProtocol Label Switching (MPLS) creates 'virtual circuits' or tunnels, across an IP network, service providers use MPLS to provide 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.

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 wireless solutions 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 and 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 and Radio Frequency (RF).

The VSAT Alternative

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

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

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 the reliable and scalable means to long distance communication for enterprises.

WI-FI

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 Diary, 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 13kms 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, it deployed wireless outdoor access points and 23 dBi 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.

WIMAX

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 simultaneously 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.