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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.
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 Tele.com, 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.
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: www.trai.gov.in/cpaper22.htm
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.
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 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.
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 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.
CDMA
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.
GSM
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: soutimand@networkmagazineindia.com
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