I have a web application . I want that application to be hosted.I want the band width needed to run the application effectively . The application is used by 4 systems. The calculation should consider all the factors like network traffic, download time etc.
If all 4 systems can be located in the same facility many providers offer free bandwidth/transfer between servers over a private network.
If they need to be located in different datacenters you would need to look at the amount of data that will be transferred between the systems - there's no real way for anybody to estimate this for you based upon what you've given us because you haven't given us any real details to go on.
MikeDVB is correct, if everything takes place in a single DC and the traffic does not travel out on to the network and then back into the network (this can be accomplished in many DC's by having a private network setup) the BW could be minimal. Other than that there is no way with the limited amount information provided even to offer a good guess at the answer to your question.
Well, it is not like this actually. Ir is weird but some data centers charge for traffic between different cabinets, unless their a part of the same routing system. So the machines should be part of the same set up. However you do not provide any information about the application. So no one would say how much will it take to run it.
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