2009
02.06

Looks like Comcast is bringing their DOCSIS 3.0 technology to the Denver area (which includes Golden) “soon”. This is a good thing; current 6/1 and 8/2 tier customers will get automatic and free upgrades to 12/2 and 16/2 speeds (upload/download in Mbps) respectively when the new tech rolls out. If you’re willing to pay $10 more per month than the current 8/2 tier, you’ll be able to get DOCSIS 3 service where the modem spreads download traffic over three cable channels instead of one, for a total of 22 Mbps down, 5 Mbps up. Finally, for $140 or so, you’ll be able to get 50 Mbps down, 10 Mbps up. Another perk: due to the DOCSIS 3 upgrade, we’ll also get DOCSIS 2…current Denver customers are slumming it on the 10-Mbps-upstream-per-channel DOCSIS 1.1. The endgame: 3x the upload capacity per node, for 2-4x faster uploads while on PowerBoost, and the ability for tiers with more than 2 Mbps of upload built in to exist.

The flip side of the coin: caps and “protocol agnostic” throttling. All residential tiers will get a 250GB usage cap per month (even the $140 one), with anyone above that running the risk of being cut off service-wise for a year ont their second violation. Yes, 250GB is a lot, however it’s reachable by such things as online backup and HD video streaming by multiple people. The secourse: get a business class connection, which won’t be too expensive for a 12/2 tier, which I’ll in all likelihood be switching to when the new speeds hit.

Of course, this cap assumes Comcast will be kind enough to let you hit it; you’ll probably get throttled into oblivion (or, rather, deprioritized into seething anger) before then unless you’re running your connection at full tilt when nobody else is online. Basically, Comcast’s new system, which is technically “protocol agnostic” is in reality a huge slam for anything latency-sensitive (voice over IP, gaming, video streaming and even, to some extent, web surfing). Here’s the way it works:

  1. Cable node is congested (whatever “congested” means I’m not sure…apparently the node I’m on becomes congested at night but worked just fine until the new system came online)
  2. Customer uses more than 70% of their rated download or upload speed for 15 straight minutes (on higher-speed tiers in DOCSIS 3 territory this is hard to do, but here an HD video stream or an online backup will do the trick, not to mention anything P2P-related)
  3. Comcast’s system deprioritizes customer’s traffic behind everyone else’s who hasn’t “broken the rules”, leading to huge spikes in latency and “jitter”, or variance in latency…which makes web surfing painful any any realtime activity unusable other than IM…more on this later
  4. Customer drops to 50% or below usage of their connection over a 15 minute period
  5. Comcast re-prioritizes customer’s traffic

I thought the system wasn’t going to be too horrible. After all, Comcast said that deprioritization would only mean that, if the data “bus” was full your packets might need to wait a few buses (each “bus” is 2 ms from the next one) before getting on the bandwidth bandwagon. Even 50 buses would only delay communication one-tenth of a second (this is actually quite big in terms of cable connectivity, but let’s ignore that for the moment).

The problem: Comcast’s “bit buses” appear to be running on RTD; I figured out my traffic was being deprioritized when web browsing became almost unusable and latency to the first hop of COmcast’s network skyrocketed to several hundred, or even a few THOUSAND, milliseconds. To put som eperspective to this madness, Comcast’s normal cable first-hop latency is somewhere between 5 and 15 ms, and Qwest interleaed (high-latency) DSL, which is standard fare in these parts, is around 45 ms. Cell phones on 3G have first-hop latencies of 80-120 ms. Satellite has first-hop latencies of between 500 and 1200 ms. So, when your traffic is deprioritized, your connection may well go right into the crapper. Granted, the conditions for throttling had been met on the upload side due to BitTorrent, but that the cable node was congested was news to me. Guess any activity on my part during any “peak” time does that to Comcast’s rather outdated coaxial cable network.

One more thing: upload and download are throttled separately, so theoretically you can have one way deprioritized and the other not. The problem is that internet communications are a two-way street in 99% of cases, even if you’re downloading web pages. You have to make a request for a server to give you a file, and you have to make a response to make sure that the server delivered the file correctly. Guess what happens when you get throttled on the upstream side (highly likely if you’re doing online backup, for example)? Those acknowledgments take a little closer to forever to go through the inter-pipes, and you end up with a connection that couldn’t even win in a midwinter race against gooey molasses.

So, anyway, Comcast will be out with higher speed tiers relatively soon, despite the relative lack of competition from Qwest on the front of decent internet speed. Maybe it’ll mean that people will be throttled less fequently, since heavier users will supposedly switch to DOCSIS 3 plans which will spread their usage over three cable channels instead of one, thus creating a bit more capacity…aside from the fact that three channels are better than one for said heavy users. Still, when Lafayette, Louisiana is running fiber right and left, even Comcast’s newest developments look downright pathetic. Qwest? No fiber plans anytime son, and their fastest speed tier is effectively 17 Mbps down, 700 kbps up, which Comcast pretty much matches right now on the business class side of things, no network upgrades required.

Not that I dislike upgrades…if Comcast’s nodes are congested here, by golly fix ‘em, by hook or (preferably not) by crook!

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