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How VSAT internet connectivity works?

How VSAT internet connectivity works? I would like to understand how it this connectivity works.. I am wondering the 'latency' would be very high, in which case do we use this VSAT connectivity?
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Latency on a VSAT connection is about 500 ms.  So some technologies, such as VPN's, do not work well (if at all) in a VSAT enviroment.  If you have lots of little bits of traffic to transfer VSAT is not a good network connection method.

IMHO VSAT sould be used when it is the ONLY option, as a possible backup, or when you don't care about performance and it is cheaper than "land" lines.
beer9Author Commented:
Thank you! :-)
The latency problems can be very serious to TCP, but there are solutions available that will spoof the TCP acnowledgement improving your throughput andf reliability.
There is a misconception about latency on satellite..

When people speak about 500 - 600 ms this is Round Trip Time, or the result of a PING, IE: the time it takes a packet to travel from you to receiver and then back again.

When you consider a UDP one-way stream of data such as a VOIP call, this latency is halved.  It is simple science... satellites are approx 36'000km away so this is approx 72'000km trip, up and down. Speed of light is 300'000 km/s therefore A end to B end of a one way satellite stream is just under 250 msecs ..

This varies with the actual elevation of each antenna and any modem processing delays and of course additional terrestrial latency, but as a rough guide is accurate enough.
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