Some insight:
Companies which own international bandwidth (like RCOM, Bharti Airtel) have found a new
business model to make money from underutilized network during non peak hours. They sell bandwidth for releasing Indian content in US. This content (such as movies to be released in theater) is very heavy (Few TB) and is required to be delivered at a particular time (content owners hand over content to distributor just before the release in order to minimize piracy). The network utilization follows a particular pattern and especially during the night, network utilization falls below 10% of peak utilization. So, generally they choose this period and block very high portion of bandwidth (lets say 80%) for this content. In order to avoid any breakdown in the network, they might throttle the torrent and other data hungry program.
I do not want to suggest that this is the reason for throttling at a particular time but this can be one of the reasons.
With the amount of capacity the ISPs such as Bharti have available to them, a few TB here and there doesn't affect much of anything. To put it in to context, Bharti could transfer 10TB of content over the lit capacity of it's international pipes (not total capacity, but lit capacity) in about 15 minutes without blinking an eyelash.
The setup of content distribution networks is designed in such a way that the content is sent from India to the US and is stored in the US itself for distribution in the US through whatever channel - be it a movie theatre,
netflix, the cable providers or others.
Secondly, network utilization at off-peak hours is significantly more than 10%. Indicative traffic graphs show about 30% usage on average - in Mumbai that number is as high as 50%, in Delhi about 30%, in Chennai about 40%. This is significantly higher than graphs I've seen for ISPs in other countries, however I expect this is due in part to the popularity of "night unlimited" type plans in India.
Thirdly, the direction of traffic is wrong - if Bharti is sending content to the US, that's going to have little (if any) effect on the downloads of it's users in India, because almost all users (especially on
ADSL) have much less upload capacity than download capacity, and as such the theory goes that there is plenty of spare upload capacity at any time of the day.
Fourth, they simply aren't *allowed* to simply "block off" chunks of bandwidth to allocate it to some other purpose just because it's off-peak hours. They're still required to maintain their contention ratios and provide the same quality of service no matter what the time is as per whatever plan the user is on. The exception to this from memory is if the government declares a state of emergency, and that too I think a national emergency, at which point ISPs are obliged to surrender their resources to the government/military/etc (I'm oversimplifying it a bit, but it has such clauses in the ISP license agreement).
Last, but not least, the above graph shows that the user received full speeds in the night, not throttled speeds - which contradicts the theory you've put forth.
...
...I think I had another point, but I can't think of it right now.
