VSAT is a secure and reliable medium to connect geographically dispersed locations. In a situation where other connectivity options are not feasible, VSAT offers two distant advantages: less deployment time and easy manageability. A look at how Comsat Max has created a VSAT network that connects remote and major locations nationwide and the advantages your company will gain if you go the VSAT way. by Soutiman Das Gupta

Comsat Max's VSAT (Very Small Aperture Terminal) network provides nationwide data and voice connectivity to enterprises. Support for the VSATs is provided from 50 locations spread across the country. It has an extended C-Band hub in Turbhe (New Mumbai), and has built another hub which runs on the Ku-Band, very recently in New Delhi. The network topology is a mix of star and mesh.

Comsat Max started its operations in 1995. "At that time, we felt that there was a need for reliable and managed WAN solutions," said C S Raghava Rao, Head - Technical operations, Comsat Max Limited. "The predominant method of WAN connectivity was leased lines which had several disadvantages. The lines were costly and one had to apply for a leased line and wait weeks for a connection. Leased lines have bandwidth slabs and can't be shared on a network basis. Thus the capacity is underutilized. In a large network sharing of bandwidth helps in optimal use of resources, VSAT technology provides speedy, cost effective and reliable solutions to the organization."

A VSAT is a small fixed earth station which provides a communication link required to setup a satellite-based communication network. It represents a cost-effective solution for those who want an independent communications network to connect a large number of geographically dispersed sites, especially sites where any other connectivity options are not possible to implement.

SAT networks offer value-added satellite-based services capable of supporting the Internet, data, LAN, voice/fax communications, and can provide powerful, dependable, private and public network communications solutions. A VSAT has certain clear advantages over leased lines and other wireless communications media.

VSAT value over cable
When it comes to cost its not quite fair to make general comparisons between VSAT services and it's terrestrial counterparts. Charges for terrestrial services are nearly always distance-dependent, while VSAT connections cost the same whether sites are one or 1000 Km apart. And with most VSAT services the cost-per-connection comes down considerably when a customer adds users. However, Comsat Max and other VSAT service providers have considerably reduced their fees lately.

A satellite network can be installed and made operational within a week since miles of cable need not be installed. And VSATs are available in remote locations since it doesn't need the infrastructure of a telephone exchange to be present.

"Suppose a bank needs to expand it business by deploying 100 new ATMs (Automated Teller Machines) within six weeks, can you imagine the time it will possibly take to wait for leased lines? In such a case, VSAT connectivity is the best option," opines Rao.

Traditionally, VSATs had a few disadvantages: VSAT bandwidth was not very high and restricted to a few 100 Kbps. There was also certain amount of latency (the time between initiating a request for data and the beginning of the actual data transfer) between nodes. But these limitations have been overcome to a large extent due to advancement in technology. Nowadays, VSAT providers offer up to 52.5 Mbps outroute (from hub to VSAT) and 307.2 Kbps inroute (from VSAT to hub) data rates, and only 270 millisecond latency.

The young VSAT provider
In 1995 Comsat Max started service using AT&T Clearlink systems (satellite modems capable of handling TDM/TDMA traffic).

This enabled its clients to use a dedicated data transmission network and ensured reliability of transmission. The system offered 64 Kbps inroute and 512 Kbps outroute data rates. The hub at Turbhe used an extended C-band antenna and TDM/TDMA technology to support VSATs on a star topology. C-band is used extensively in Asia, Africa, and Latin America and requires a larger antenna than Ku-Band VSATs. The company had direct presence in eight cities and franchises in 30 cities.

In early 1997, the DoT (Department of Telecommunications) allowed the company to build a mesh network. This allowed an easier passage for high-speed low-latency networks because it reduced a hop, otherwise present in a star topology.

In 1999 the company deployed Skystar Advantage LAN+ using FTDMA (Frequency & Time Division Multiple Access) technology. This reduces probability of collisions and can support interactive transactions, batch file transfers, data broadcast, and voice communications. Broad-cast of audio and video are available as add-on options.

A blast of broadband
Comsat Max now uses SkyBlaster 360E (a Ku-Band VSAT) which uses a DVB (Digital Video Broadcast) standard to offer broadband Internet access to its customers. The product is a two-way satellite-based solution to enable interactive Broadband IP and multicasting applications. By using the DVB standard and IP capabilities, the SkyBlaster 360E supports most data and IP multicast applications. The product works on Ku-Band-based networks which are mostly used in Europe and North America. The company uses the services of the INSAT-3B satellite.

The platform is able to network the central hub with multiple locations spread across wide geographical areas. "It's possible to provide outroute speeds upto 52.5 Mbps and inroute data rates upto 307.2 Kbps," claimed Rao. "The SkyBlaster allows us to provide HTTP traffic acceleration and optimization, caching capabilities, QoS (Quality of Service), multimedia streaming applications like voice and video, and IP multicast applications."

A dash of VPN
"Although a VSAT network offers very high security, we believe that our customer should be offered more flexibility in the form of a dedicated network with high bandwidth, low latency, and assured connectivity," said Rao. This prompted Comsat Max to set up an Internet infrastructure to be used along with the VSAT architecture to offer Internet and VPN services in 17 cities nationwide.

Service differentiator
"What makes a difference is not the technology but the people in our organization who drive the solutions. A state-owned airline and a private-owned airline both run Boeing 737 aircrafts. But why do you think passengers prefer to fly private airlines? It's the difference in levels of service and commitment to customers," explained Rao.

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Management
"Since we have a very large network and different platforms/ devices like indoor and outdoor units and routers, we had to choose a unified network management platform that gave us an integrated view. We decided to use Computer Associates' Unicenter TNG. It provides an integrated interface that enables us to keep a tab on the entire network from one screen. It also provides audio and visual alerts. If a device goes down, the system opens a trouble ticket (a kind of a maintenance request). If the problem is not solved soon, the ticket is escalated to a person of higher authority in the form of an SMS or
e-mail message," explained Rao.

Myth
The cost of VSAT services has decreased dramatically in the last few months. This is indeed a good sign for large enterprises and smaller companies who are poised for growth.

"It is a myth that VSAT has seen its end. Around 30 percent of all communications worldwide rely on VSAT, and its deployment keeps increasing," said Rao.

Soutiman Das Gupta can be reached at soutimand@networkmagazineindia.com