WAN: Why Be Pound-foolish?

VoicenData Bureau
New Update

Of late, some awareness has come about on the need to segregate private WAN

networks containing company databases and public networks such as the Internet.

However, there is still a lot of confusion on what a private network is, and why

it is required despite the existence of various public networks.


Cellular and WLL networks like GSM, GPRS and CDMA are public networks and

have access to other public networks like PSTN and ISDN and the routed IP

networks of telcos and ISPs. Hence these cannot be used in building real private

networks (RPNs).

RPNs are formed by connecting company locations through dedicated

point-to-point leased lines, in star or mesh/star topologies, and routed through

router-like devices. These may be either pure data networks (RPDNs) or

integrated real private networks (IRPNs). All RPNs are totally secure, as the

point-to-point leased lines between company premises deny physical access to

company outsiders.


Path redundancies in RPNs have to be achieved by providing additional leased

lines in star topologies, or alternative paths in mesh topologies. In fact, RPNs

should not be backed up by any public domain connections like ISDN, PSTN, PDN or

VPN, and VSAT systems. Backup through public or shared domain connections

defeats the very purpose of having an RPN, as this exposes the network to the

public domain access, and to professional hackers.

Pure data RPNs or RPDNs add to a company’s cost, as the existing STD/ISD/local

PSTN communications costs between company locations continue.

IRPNs not only provide a secure communications backbone for the WAN, but also

take care of a company’s total inter-locational communications, in the form of

speech and fax, in addition to data. Once an IRPN is established, the inter-locational

STD/ISD communications are eliminated.


Prevailing IRPN technologies are the VoIP technology, and the new and

patented PVDTN technology.

The principle difference in the two technologies is that


n In VoIP, speech communications

is through voice packets queuing with data packets in the routed IP WAN, calling

for large bandwidth leased lines in the WAN for acceptable or toll quality

(normal telephone like) speech. The speech communications in the LAN could be

either through circuit switching and normal telephone distribution, like an EPAX

system, or packet switched through IP telephones over the LAN. The latter is

more expensive.

n In PVDTN, the speech and fax

communication is circuit switched end-to-end through the LAN and WAN,

facilitating toll-quality speech over low-bandwidth digital or even analog

leased lines. Data communications are always packet switched through fixed data

pipes forming a routed IP WAN, or through switched data pipes formed by circuit

switching between locations.

The lower bandwidth leased line requirements of PVDTN produces very low

operating costs, about one-third of a VoIP network with the same connectivity.

This enables companies to reduce their existing communications costs by 40—60

percent, by eliminating the STD and ISD communications expenses between



Although VoIP networks also eliminate STD/ISD communications between

locations, the overall costs of companies increase due to an increase in

operating costs of the network, especially when toll quality speech is a must.

Thus, the two best ways of building your WAN is either a routed IP RPDN, or

through an IRPN using the PVDTN technology, which is a mixture of routed IP WAN,

and circuit switched voice and fax communication. Due the reducing costs of long

distance call charges, VoIP is not a cost effective option, due to its high

annual operating cost.

The next question is: how does a company interact with the information

highway–the Internet.


Many a company CIOs ask the question, and very rightly so: "How can any

company afford to isolate itself from the Internet, in today’s scenario of

e-commerce?" The answer is, by having a secure private internal data


To facilitate the availability of up-to-date publishable information about

the company on the Internet; to facilitate the inputs from clients, vendors, and

company officers in the field, through interactive screens on company Web pages,

or through e-mail; or access to information required by field officers for

dealing with their clients, a secure transfer system (STS) has been devised,

which facilitates information exchange back and forth between the public

Internet and the private company LAN/WAN, at major company locations, without

impairing the security of the private LAN/WAN. The STS denies access to the

company private LAN/WAN from the public domain networks like Internet, PSTN,


Another logical question being asked by CIOs is: "If access to the

Internet is denied to private company LAN/WAN, how does one provide Internet

browsing facilities to employees in the office premises or outside?" This

issue can be addressed cost effectively. The additional costs of extending the

Internet LAN to those employees who need to browse the Internet during working

hours from their own work stations is insignificant compared to the costs that

the company would incur if its databases were damaged by hackers.


The usage of integrated information systems like SAP and Baan by companies to

run their day-to-day businesses is increasing.

The increasing dependence on such computerized data makes it imperative to

have high levels of security. This is currently non-existent in the prevailing

methods of connectivity being practiced, primarily due to the lack of awareness

of the implications of such connectivity, by those who are providing them and

those who are accepting them.

PK Mitra, managing director, MIDAS Automation & Telecommunications