managers will now have many options for fulfilling WAN
link requirements. It will become a challenging task
just deciding which one to use. by C.N. Ram
has come a long way since it opened up its Telecom sector.
Over the past few years, we have made considerable progress
in creating state-of-the-art, carrier-class telecom
infrastructure in the country. This has been largely
due to private operators investing heavily in infrastructure,
and BSNL also catching up and upgrading its own infrastructure.
Private service providers are continuously increasing
their coverage and introducing value-added services.
This has opened up new vistas for network designers.
The network medium, which physically carries data packets
from one point to another, happens to be the most critical
component in WANs. Reliability of the network hinges
around reliability of the medium, as it is the weakest
link in the overall network architecture.
In the years ahead, leased lines need not be the only
choice for the network medium.
This has posed some new challenges and opportunities
to network managers. In the old days, when the requirement
for a WAN link arose, the network manager did not need
to think about the options as there was only BSNL (for
leased lines). He had to apply to BSNL, wait for them
to commission the link as per their time frames and
then pray that the line was up and running. Users did
not expect too much and were contended with whatever
uptime was available.
VSATs have been around for quite sometime now but are
typically unaffordable due to high costs. The cost factor
arose because of the unique frequency band that was
used only in India. VSAT equipment had to be manufactured
explicitly for the Indian frequency band, so economies
of scale could not be achieved, leading to higher equipment
cost. To add to that, only ISRO satellites were permitted,
and licence fees were very high.
In 2003, the scenario will change drastically. Network
managers will now have many options to choose for fulfilling
WAN link requirements. I'm sure it will become a challenging
task to decide which one to choose.
The reasons attributed to this new challenge are many.
On one hand, BSNL/MTNL have achieved substantial performance
improvements. On the other, more private operators are
spreading their coverage and introducing value-added
VSAT technology has also advanced and broadband VSATs
have arrived. Due to availability of the KU band in
India, cheaper VSAT equipment is available, which makes
the VSAT costs almost equivalent to that of other media.
Mobile operators have introduced data services based
on GPRS and CDMA. To top it all, radio technology has
also advancedcheaper and higher bandwidth radios
are available at much lower costs. More frequency bands
are permitted making it more feasible and reliable.
All this leads us to the conclusion that the Indian
market has matured in terms of WAN media availability
and reliability. This is the reason why network managers
will have to take more informed decisions while selecting
While there can't be a thumb rule which states that
a particular medium is better than another, general
guidelines will definitely be helpful to arrive at the
best bet in a given situation. The following general
considerations will gain significance in the decision
So far leased lines were only available from BSNL/MTNL,
and performance was very inconsistent. Single window
co-ordination has been a major issue in the commissioning
and upkeep of the lines. But there is considerable improvement
in consistent performance and accountability. This is
largely due to competition created by private operators.
A leased line is an ideal medium for bandwidth hungry
and low latency applications. (e.g. multimedia applications).The
performance is much better in metros than in urban/rural
areas. The commissioning time is a little higher than
for all other media and there could be issues in redeployment
in case your location is liable to shift. Normally you
are bound to the service provider for a year by paying
Leased lines are now offered by many operators. If you
have a presence all over India, choose an operator who
will have presence in multiple locations.
Usually, both capital and revenue costs are medium.
Since tariffs depend on distance, long distance leased
lines may attract high revenue costs. However, due to
increasing competition, leased line costs are expecetd
to slide further.
VSATs are suitable for applications characterised by
bursts of traffic, or applications which work on a broadcast
basis. However, due to the inherent latency of the VSAT
technology, it may not be suitable for real time applications.
With the introduction of KU band-based VSATs, it may
be an ideal medium for applications like Internet browsing
where traffic is asymmetric and latencies are tolerable.
VSATs are generally hassle free from a commissioning
and maintenance viewpoint. However, clear rooftop space
of about 10 square feet is required for the installation.
Relocation is also not an issue subject to availability
of rooftop space. One should be aware of extra-terrestrial
phenomena like sun outage, which render VSATs unusable
for that duration. Such phenomena are not within the
service provider's control. But generally, uptime is
There has been a dramatic reduction in the equipment
cost and operating cost of a VSAT over the past year.
While equipment cost is more or less similar to leased
lines, operating cost may depend on the volume of traffic
pumped in to the VSAT. For very high traffic, costs
could turn out to be much higher than leased lines.
Line-of-sight Radio links
Radio technology has shown significant improvements
in terms of availability of higher bandwidths over the
past few years. Equipment is now available for as high
as multiples of E1 link capacity, at a reasonable price
has also improved as multiple frequency bands are released
to commercial operators.
Goverment has de-licensed the 2.4 GHz frequency band
to encourage widespread use of Wi-Fi (802.11b/a). However
this is bound to raise network security issues, which
are being addressed as new standards for WLAN emerge.
Radio links work well in urban and rural areas where
it is difficult to lay cablesthe only restriction
being feasibility of line-of-sight. Another potential
deployment of radio links could be to connect clusters
of offices within a city to a central office.
There is no bar on the type of applications, which could
be real time multimedia applications or other bandwidth-hungry
applications. One limitation is on the distance that
can be covered by a single link. Another constraint
is that, at times, it becomes impossible for the provider
to trace and curb the cause of disturbance on the link,
especially if it happens intermittently.
Radio links usually entail the highest equipment cost
while the operating costs are comparable to that of
Data over cellular
Data over cellular is a relatively new offering in the
market. It is expected to mature and become more and
more dominant in the marketplace in the years ahead.
In its present form it is suitable for low bandwidth
applications such as ATMs or Point-of-Sales terminals.
However, as the bandwidth offering improves, it can
be a real threat to all other media. One
has to watch for this medium in the coming years. Equipment
costs are very low and operating costs could also be
comparable to that of leased lines.
Managed network services
These are value-added services (such as VPN) offered
by service providers. The choice of media depends on
availability in a particular area. This type of service
is generally suitable for small and medium enterprises
who may not want to be concerned with the maintenance
of their wide area networks. The service provider manages
and monitors the entire WAN infrastructure, including
the CPE (customer premise equipment). Managed services
are a good bet for applications that have moderate traffic.
VPN will become an attractive proposition in future
as security and QoS issues are addressed with advancements
at the higher layers of network topology. The quality
and quantity of Internet bandwidth availability is also
expected to improve significantly, which can help VPN
be more suitable even for critical business applications.
In summary, easy availability of high speed and reliable
connectivity in the country can lead to more applications
being launched on corporate networks (e.g. video conferencing,
intranet applications, group collaboration etc). I believe
year 2003 will mark the beginning of a very challenging
and rewarding era for network managers who were so far
constrained by the laws of the land.
The writer is Head, Information Technology,