Just a few thoughts (some of which may be emanating from my posterior, but no matter):
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Brian Butterworth Sent: Monday, April 14, 2008 5:38 PM To: [email protected] Subject: Re: [backstage] iPlayer and the ISPs - a solution > but my experience of them is that transparent proxies reduce overall > performance because they need to get in the way of each and every HTTP > transaction. Yes, I suppose in theory, but use of appropriate routing and firewalling means not in practice. Though adding this before the application layers will introduce a separate latency of its own. It would be difficult to filter such traffic on port admittedly, but not on other things, like source and dest addresses (see below). I wouldn't have thought that the small increase in latency would be noticeable for a several hundred megabyte file. I would have thought otherwise, since the latency is, almost by definition, indeterminate and could, in fact, be appreciable, especially if under high load > 3. Store and forward: Locate MIRROR SERVERS inside the ISP network. > This seems a much better idea. But the BBC's network does a LOT of this mirroring and load balancing stuff already, certainly if you look at some parts of their operation (like News) and especially with HTTP. It wouldn't work otherwise. And when it doesn't quite work like that, performance does suffer. It sounds a lot like some kind of Cache. And another question is *who* is going to pay for the servers that speak RTMP? This sounds like some kind of revenue driving scheme for the BBC's commercial friends. > the ISP provide the BBC with rack > space 'inside' their networks for mirror servers. A generic cache would be much more scalable, if the servers only mirror BBC data then this does nothing to solve problems with other sites. How does one mirror this data? Will it be available via rsync? Will it be mirrorable by *anyone* or does the BBC intend to pick and chose commercial ISPs to provide better access to. Again very shaky ground. And even though technologies like rsync are largely differential, the traffic generated from such syncing is not trivial, especially if the content is in binary formats and not textual. Because constructed deltas that are used for syncing may not be that small. And, more prosaically, once the data is inside the ISP's networks, who is responsible for it? > - change the main BBC iPlayer to redirect requests for the content to > the Mirror Server located in the ISPs network. Really unscalable, how is the BBC going to know which ISPs have mirrors and which do not? This would require each ISP to notify the BBC. Just seems wrong. Having every Content Provider have to speak to every ISP seems to go against the core of the Internet. If the BBC is decides to provide such a service, what is wrong with it whitelisting those who sign up to use it? Not necessarily something I agree with but not unfeasible from a technical point of view. Potentially very fiddly however and, as rightly pointed out, not hugely scalable for the long term. If a pipe on the Internet is not running at 100% it is being underused! On the other hand, a pipe running at 100% could clearly be considered borderline congested. Andy [1] <http://www.opsi.gov.uk/acts/acts1998/ukpga_19980041_en_2#pt1-ch2-pb2-l1 g18> - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/[email protected]/ -- Please email me back if you need any more help. Brian Butterworth http://www.ukfree.tv
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