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Comcast's Congestion Catch-22
An anonymous reader sends us to Telephony Online for a story about Comcast's second attempt at traffic management (free registration may be required). After the heavy criticism they received from customers and the FCC about their first system, they've adopted a more even-handed "protocol agnostic" approach. Nevertheless, they're once again under scrutiny from the FCC, this time for the way their system interacts with VOIP traffic. By ignoring specific protocols, the occasional bandwidth limits on high-usage customers interferes with those customers' VOIP, yet Comcast's own Digital Voice is unaffected. Quoting:
"The shocking thing is just how big a Pandora's box the FCC has appeared to open — and it just keeps getting bigger. When the FCC first started addressing bandwidth usage and DPI issues, it quickly found itself up to its knees in network management minutia. Not long after that, it followed another logical path of the DPI question and asked service providers and Web companies about their use of DPI for behavioral targeting. Now it seemingly has opened up huge questions about what it means to be a voice carrier in the age of IP. It's not hard to imagine the next step: What about video? Telco IPTV services are delivered in roughly the same way as carrier VoIP services — via packets running on the same physical network but a prioritized logical signaling stream. Is that fair to over-the-top video service providers?"
If Comcast is having major network congestion then why did they automatically double everyone's download speeds? I got a letter a few days ago saying that I now get 12 down rather then 6. Seems like a BAD idea if they are having congestion issues...
~ Mooga
It would have been first, but someone was on the phone.
If someone is doing very high traffic, enough to get into Comcast's temporary "QOS Low" category, they are probably sending and full rate. If you are sending at full rate, the typical end-host NAT and buffering alone will cause bad quality for VoIP (search for VoIP and BitTorrent for a lot of such tales). There is nothing Comcast's network management really does to affect things in this case anyway.
Comcast's network management should only cause additional VoIP issues when the big transfer STOPS and the VoIP call is made within only a few minutes (before the user's link is reclassed back into the "QoS normal" category).
Test your net with Netalyzr
Why do ISPs insist on being more than just a pipe? It's so dumb no one wants them to be anything else. Do they just not feel useful when they are a pipe?
If you have VOIP, don't set your kitchen on fire during high congestion periods. Please people, a little take a little personal responsibility.
Leave the gun, take the cannolis.
Why don't they just UPGRADE THE PIPES.
My god every other first world country has huge bandwidth where these types of things aren't even a consideration. Yet comcast just whines because you can't run everything and be fair on tiny pipes.
The ISP supplying my workplace regularly blocks HTTP for up to hours at a time. Nothing else, just outgoing(!) port 80. First connections get dropped silently, then after a while it moves on to forged TCP reset packets when trying to connect to anything. Which is pretty worrying because they're the only ISP available here.
because they want to milk the current technology and still profit from it as long as they can. I know I work with these guys. No need for FTTH until there's competition.
They'll just let the FTTH come in and then merge with that company or acquire them outright.
the typical slogan of "they bought us" comes into play here. As cable becomes telco that's just what happens. Only you have to wait until the market forces make that happen. Here in NY Verizon basically takes about 10 thousand households away from time warner every month. Merger aquisitions! It's on the shopping list, as Larry Ellison likes to say :)
"Catch-22" implies a no-win situation. Comcast (and the other ISPs) have done this to themselves. They advertise unlimited Internet access (or make it seem like they're offering unlimited access) and then get upset when someone tries to use it.
The ISPs should start advertising their download speed, upload speed, and bandwidth caps openly. Offer additional speed and bandwidth for a reasonable price. And if your infrastructure is such that sometimes you'll need to throttle someone, make it clear upfront how and when such throttling will happen.
Right now, on Comcast's sale page, they only list the download speed of their connections. I couldn't find their upload speeds or the bandwidth caps (which I know to be 250GB). As far as I know, Comcast customers have no way to check to see if their being throttled or if they're near the bandwidth cap.
It's really no surprise then that customers are upset.
If they are treating their own VOIP differently than other traffic then it isn't "protocol agnostic" at all.
Sometimes you have to keep on complaining. I had a similar problem that wasn't solved until they finally sent out a team of real technicians with a spectrum analyser. Even then, it took them several visits to locate the faulty equipment that was generating interference on the local cable distribution system.
Mea navis aericumbens anguillis abundat
Why do you hate America so?
Sacred cows make the best burgers.
Comcast is a cable company, right? So isn't this just because their VoIP can be put in a separate Docsis channel (and prioritised accordingly), while 'regular' VoIP is sent as normal data?
Join the anonymous, help develop the network: http://www.i2p2.de
I don't want to spend an hour writing a treatise on this, but I do think I need to make a few things clear.
Several issues are convolved here, and the "right" answer to each individual issue is not obvious (at least not once one factors in political and business viewpoints), so the convolution is essentially a mess. Like the original poster of the story, I have to assume that the FCC decided intentionally to delve into the mess. Anyway, here are the real issues:
1. There is (as far as I know) no new technology here. The PacketCable specs, which define how cable operators (most of them, anyway) implement VoIP were released in 1999. Comcast (like other US cable operators) has been deploying this technology since about 2002. As far as I know, the only part of the spec that Comcast don't really implement is the security portion. In any case, the specs are public and have been so for nearly a decade.
2. There is a fundamental technical difference between over-the-top VoIP (i.e., service provided by a third party such as Vonage) and telephony provided by the cable company.
3. The cable company can differentiate between its VoIP (or any other service needing preferential Quality of Service (QoS)) and ordinary so-called "best-effort" traffic, which is what is used to carry everything else, including over-the-top VoIP.
4. The reason for this is that it is the only entity that has access to the Cable Modem Termination System (CMTS), which controls the microsecond-by-microsecond details of traffic flow over the plant between a customer and the cable operator's facilities.
5. It is reasonable (from the cable operator's point of view) that since it owns the CMTS (and CMTSes are not cheap either to acquire or to manage), it's not voluntarily going to let some other company control any part of its operation (especially since if that gets screwed up, the customer experience is impacted).
6. Looked at from the point of view of guarantees applied to services, this looks like a violation of net neutrality, since over-the-top operators have to fight for bandwidth against things like P2P and web browsing, while the cable operator's phone calls don't have to do so (they have QoS guarantees).
7. But there is no law against violating new neutrality (as far as I know, in the US anyway). IANAL.
8. One can also argue that although it *looks* like a violation of net neutrality, it is in fact not such a violation, since from the viewpoint of what is happening inside DOCSIS (the protocols used to manage bandwidth on the plant between the residence and the cable company), over-the-top VoIP looks completely different from the cable company's offering. From that technical viewpoint, they can be considered two different services, and hence it would (presumably) be fine even under net neutrality principles to treat them differently.
Those are the basic ideas (although of course I've just summarized; it would take a lot more space to really describe all the details). But the basic point here is that there are lots of issues and viewpoints, some business-related, some political, and some technical. And much though one might like to demonize one party or the other, in this particular case the issues don't really seem to lend themselves to such a simple analysis.
Disclaimer: this was a quickly-written post of my initial impressions given the rather sparse (and not unambiguous) information available.
Bandwidth is a commodity. As such is interchangeable: the provider of a commodity is in competition with everyone else providing the same commodity. They have to differentiate themselves based on price, which they can only do by cutting costs and increasing efficiency. Though market competition is in our best interests as consumers, it isn't in theirs. The last thing a company wants is for market competition to work efficiently to drive down their margins. That's why they will do everything they can to avoid selling a commodity: product differentiation, branding, and so on - strategies that effectively create mini monopolies (you don't buy an MP3 player, you buy an iPod; you don't buy shoes, you buy Nike).
That's the main reason. Another, which applies especially to monopolies (hello telecoms!), is price discrimination. A company would like to charge each customer as much as that customer can afford to pay, but they don't want to lose business with a price that's too high. By developing different classes of service they can coax more money from those able to pay more. The classic example is first-class seating on flights. How much a customer is able to pay may also depend on how much the service is worth to them. It may not cost the telecom company any more to provide bandwidth for, say, VoIP users than for WoW players, but VoIP customers may be able to pay more because it saves them money elsewhere.
It is the role of good market regulation to ensure competition works effectively to drive prices down towards costs. That is broadly good for consumers and for the economy as a whole. Companies - especially incumbent companies - should be expected to do everything in their power to fight to break the market. And they do.
"Comcast Digital Voice uses Internet Protocol and not the Internet. Comcast Digital
Voice calls travel on our private, managed network -- not over the public Internet. That makes
it superior to other 'Best Effort' services delivering phone traffic over the public Internet."
Source (emphasis mine): http://www.comcast.com/MediaLibrary/1/1/About/PressRoom/Documents/ProductsAndServices/digital_voice.pdf
My comments here are my own; I do not speak for my employer.
That is just way too much effort for pleasure. It's much simpler to twist a belt around your neck until you pass out. The rush is amazing! Every AC should try it a few dozen times a day. :-)
Every other first world country has immensely higher population density.
Wrong, unless you're saying that Finland, Sweden, and Norway are not in the first world. http://en.wikipedia.org/wiki/List_of_countries_by_population_density
I live in Finland which has about 5 million persons at a population density of 15.6 per sq.km, while the US has about 300 million at 31 per sq.km, or double Finland's population density. Actually, about half of Finland's population is near the south coast (especially around Helsinki and Turku), while I'm in a rural area 300km north of Helsinki, so our regional population density is a bit lower. The largest town within 200km has about 80,000 people.
I have fiber to the house with 100/10 service available. The service is eur55 per month, including IP TV. If it's possible in the countryside in Finland, then it should be possible in most of US, where local populations and population densities are higher.
In fact, there are substantial areas of the U.S. with quite high population densities and local populations greater than all of Finland. Example: New Jersey, with 8 million persons at 438 per sq.km, and many millions more in adjacent areas. http://en.wikipedia.org/wiki/New_jersey
Your argument based on population density is a load of bollocks. You're just screwed by your ISPs.
Those who can make you believe absurdities can make you commit atrocities. - Voltaire
Well of course.
If they offer a netflix alternative expect that to be a better performer due to shaping as well.
Most people will just think the alternatives suck and choose comcast's service instead, never the wiser.
---- Booth was a patriot ----
We're still not doing congestion control very well. DOCSIS 3.0, the new cable modem/hub standard, has many congestion management features, but they're a collection of features, not an integrated strategy.
Realistically, there are two QoS options a congestion strategy for general IP-based networks can deliver:
There are fancier reservation schemes, where you can reserve bandwidth, but they only work when all the players in the path cooperate, which tends not to happen. But there's no reason not to get the simple mechanisms above right.