On Wed, Nov 19, 2008 at 11:42 AM, Drew Calcott
Maybe I've missed something here, but does implementing traffic shaping on content that is sitting in a local cache seem a little bit silly...?
Not at all. For starters much/most of the data isn't going to be in the cache anyway, so shaping that traffic makes sense as it's real bandwidth - both from the Internet as well as to the client. For content that is in the cache, the odds are that you're going to be able to send it to the client far faster than they would get it if the cache didn't exist. Now, if the purpose of the cache was to speed up client access this would be a good thing - but that's generally not why ISPs are using P2P caches. ie, should the customer benefit from something the ISP has done to save themselves money - especially if in doing so it reduces the amount of money the ISP saves? Ask that to 10 people and I'm sure you'll get 12 or more differing answers. There's plenty of claims you can make here, from "the more the ISP increases the speed of the P2P download, the more likely the user is to download even more content, and thus use more bandwidth and negate the benefit of the cache for the ISP" to "the faster the content downloads the faster the user will turn their computer off and go watch what they just downloaded". I don't think anyone has done enough research to show what actually occurs in these situations. To tell you the truth, I'm not sure if most ISPs shape traffic that hits the cache or not - It's not a question I've ever asked, but I will start asking it now! And is it really fair to count data that is merely being pushed from
inside their own network towards people's (rather insignificant) usage caps?
This is a country-biased perspective. Many countries don't do caps, so it becomes more relevant. Even for countries that do caps, the expectation is that every user won't download as much as their cap allows, only some of them will. Here in the US caps generally don't exist. Comcast has recently introduced a 250GB/month cap on some users, and you wouldn't believe the screaming... Scott