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Date: Sat, 20 Oct 2007 19:46:34 -0500 From: Eric Spaeth <eric@spaethco.com> Reply-To: eric@spaethco.com To: nanog@merit.edu In-Reply-To: <20071020232137.GB44916@ussenterprise.ufp.org> X-SpaethCo-MailScanner-From: eric@spaethco.com Errors-To: owner-nanog@merit.edu Leo Bicknell wrote: > I'm a bit confused by your statement. Are you saying it's more > cost effective for ISP's to carry downloads thousands of miles > across the US before giving them to the end user than it is to allow > a local end user to "upload" them to other local end users? > Not to speak on Joe's behalf, but whether the content comes from elsewhere on the Internet or within the ISP's own network the issue is the same: limitations on the transmission medium between the cable modem and the CMTS/head-end. The issue that cable companies are having with P2P is that compared to doing a HTTP or FTP fetch of the same content you will use more network resources, particularly in the upstream direction where contention is a much bigger issue. On DOCSIS 1.x systems like Comcast's plant, there's a limitation of ~10mbps of capacity per upstream channel. You get enough 384 - 768k connected users all running P2P apps and you're going to start having problems in a big hurry. It's to remove some of the strain on the upstream channels that Comcast has started to deploy Sandvine to start closing *outbound* connections from P2P apps. -Eric
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