I'm trying to think this from an ISP's PoV. Wouldn't it be a win-win for all if a user from mumbai is sent to mountain view from prabhadevi(PD) instead of mumbai>bangalore>mountain view? Could the cost to get the data from blr be less expensive compared to PD? But you said "free bandwidth" wrt to PD. If it's free then why are they diverting users all the way to bangalore?
I don't think you quite read everything quite right - NONE of what you're seeing is coming from Mountain View on the fly - but if it was, it would be coming in from
Google Mountain View or whereever to Google Mumbai on pipes that Google pays for (hence the mention that it's kind of like "free bandwidth").
As far as Spectranet is concerned, they only know 1 thing: that the content is coming from Google's caches. Where the servers are located or how the data gets there is not even a factor for Spectranet, nor does it cost them any differently whether the content is cached in Mumbai or the next nearest set of servers (most likely Singapore) or Mountain View itself - as mentioned, getting the data from it's nearest origin (or indeed, Mountain View itself) is Google's problem and has absolutely nothing whatsoever to do with Spectranet or it's traffic capabilities.
As I also mentioned, the servers you're downloading from in Mumbai/Prabhadevi are in the same cluster as the servers I hit and may include the same physical machine(s) that I or users on several other ISPs hit (assuming the ISP has configured it's routing correctly).
HOWEVER
Spectranet *does appear* to have at least 1 Google Server appliance in it's Data Centre in Bangalore which does all this caching too. Being that this server is in Spectranet's DC on Spectranet's network means that Spectranet does have to take care of all the routing to/from that box, and since you get better performance from a caching server in Google's network than you do in Spectranet's network, it says more about how much bandwidth Google is throwing about in it's network as compared to how much Spectranet is throwing about in theirs.
Either SN engineers are too stupid or too slick.
Exactly the opposite, actually, but it does present you with a funny problem.
This may be a bit difficult to follow, but here goes: although in theory you *should* get brilliant performance from a server on Spectranet's network, you don't, because even if between you and either server is a 1
gigabit line, the factors limiting you from doing so are as follows:
Distance from Mumbai to Bangalore;
The line from Mumbai to Bangalore is probably rated at 1 or 10gbit/s if it's leased - I'm not sure how likely it is that they've got dark fiber between cities;
"Competition" from *all* of Spectranet's users between Mumbai & Bangalore for *all* types of network traffic (including all the Bangalore users traffic demands), PLUS; Spectranet limiting the speed of your traffic on the Mumbai-Bangalore route to the speed of your plan so you get a maximum speed of 256kbit/s/31kbytes per second rather than leaving it unrestricted
WHEREAS
Not only is the distance much less;
From Spectranet to Google Mumbai you're looking exclusively at traffic from Spectranet to Google ONLY, the utilization is lower PLUS;
Unlike the Mumbai-Bangalore traffic, it does not appear to be restricted in speed on that link.
To summarize: Spectranet is doing what it's supposed to for your traffic to it's Bangalore cache, but not for the traffic to Google Mumbai. Why this is, I'm not 100% certain, but that you get 20mbit/s to Google Mumbai is a bonus - if only it were consistent that you were hitting Google's Mumbai DC than Spectranet's Bangalore DC so that your Youtube experience was also consistant.
