 sbrookPremium,Mod
join:2001-12-14
Ottawa
kudos:4
 ·TekSavvy Cable
·Rogers Hi-Speed
| reply to Stewy
Re: Throttling will continue with Rogers' new usage plans This issue applies only to cable modems ...
Cable is a shared medium, particularly for its upstream. There is bandwidth available for only so many simultaneous upstream data paths on a given cable segment. The CMTS (Cable modem termination system - essentially the modem and controller at the cable head end) control when modems can transmit on your cable segment.
When your modem has data to transmit, it must do so by taking part in a bidding war. The CMTS says "Transmit on frequency X in time slot NN" There are only so many available time slots and frequencies available. The bidding war is a freeforall in another time slot. If your modem doesn't get assigned a slot in the current bidding time slot, it has to wait for the next and bid in that one. The bidding process is kind of like the old manual people on the floor type stock exchange!
So the upstream is very limited. BitTorrents are not just download, they rely on your uploading to others. Torrent users leave their torrents running for prolonged periods, and the torrents present a constant upstream traffic demand. The result is that very few torrent users on a cable segment can degrade performance for all users on the segment because they fill the available upstream slots very quickly.
Throttling was introduced to a) slow the upstream demand (which is why it's a 24/7 thing unlike Bell's peak demand only) and b) to cheese off users to the point where they don't really want to use it!
So, throttling on a cable network has nothing to do with the amount of transit bandwidth the ISP is consuming (which is what caps aim to control). |
