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It’s only a zero-sum game when their network is at 100% capacity. If they were playing games to optimize usage at peak times I might not care (although they sho

It’s only a zero-sum game when their network is at 100% capacity. If they were playing games to optimize usage at peak times I might not care (although they should increase capacity in that case) but when they do this at 5AM it’s clearly bullshit. I don’t understand why you’re carrying Comcast’s water here. Nobody else does this nonsense. My FiOS connection is a gigabit all day every day. This isn’t a clever bit of network management that gives them an edge. It’s a clever bit of marketing which also allows them to cheat on speed tests. “The tapering is necessary, because PowerBoost uses up that excess capacity.” What the heck!? The network isn’t some kind of battery. There’s no buffer that gets filled up after 20MB on a TCP stream and they have to slow down to let it drain. I know you’re smarter than this.

rayiner 7y ago
> It’s only a zero-sum game when their network is at 100% capacity. If they were playing games to optimize usage at peak times I might not care (although they should increase capacity in that case) but when they do this at 5AM it’s clearly bullshit. I don't know exactly how PowerBoost works. I'm going off the description in the article you linked. The article says that PowerBoost uses up excess capacity on the network when it's available. It follows that you can't PowerBoost everybody, even at non-peak times, without lowering the maximum amount of boost. > I don’t understand why you’re carrying Comcast’s water here. Nobody else does this nonsense. No offense, but to most people on HN the physical network is an abstraction that magically delivers bits from point A to point B, and they say crazy things like "networks shouldn't be oversubscribed." I spent my engineering career sitting around layers 2/3, so reading this stuff tends to put me into rant mode.
- mikeash 7y ago
  The article I linked is a PR piece. Don’t get technical details from it. I linked to it just to show how they’re proud of their bullshit. Here’s some better info: https://www.dslreports.com/faq/14520 https://www.dslreports.com/faq/14520 Relevant quote: “PowerBoost provides bursts for the first 20 MB downloading and the first 10 MB uploading of a file respectively on select Comcast High-Speed Internet services.” Surely you admit that there is no sensible technical reason for a magic 20MB per-file limit on this.
  - rayiner 7y ago
    I can think of one important technical reason: you can do a magic per-file limit without having global knowledge about network conditions. Imagine you're an edge router or switch. It's easy to do rate limiting--you just use a token bucket to drop packets above the rate the user pays for. It's also easy to just push packets into the core network as fast as you can, and let congestion control deeper in the network even things out. Neither of those gets you the behavior you want, which is that even when the relevant route is at capacity, a user who starts a new connection will temporarily get a disproportionate share of the capacity compared to users who are doing downloading or streaming. A per-connection boost with a set limit approximates that behavior. Send packets as fast as you can for the first 20MB, then rate limit to the purchased bandwidth. By contrast, how do you implement your proposal? You could dynamically allow each connection to pump packets as fast as it can unless the network was congested, in which case you transition to allowing each user a burst. But you don't really know the network is congested, especially at the edge, and particularly at layer 2, where this rate-limiting tends to happen.
    - mikeash 7y ago
      Ok, so this is a highly intelligent and definitely user centric improvement to their network, and the only reason nobody else does it is because Comcast patented it. And the fact that the limit matches the amount of data used by popular speed testing services at the time is a total coincidence. Cool, hooray for Comcast! I sure wish Verizon would take some lessons from them!
      - rayiner 7y ago
        It would be one thing if it just helped on speed tests. But it also produced real-world benefits for things like web page downloads, MP3 downloads, PDF downloads, etc. It was an easy to implement hack that delivered real benefits for users. I don't see how it warrants so much sarcasm. Again, I think this goes back to forgetting that networks involve real systems engineering. This is real infrastructure--some guy stringing wires on a poll or stuffing Ethernet switches onto a rack. If you're approaching it from the mindset that it's some abstraction where you can just turn a dial and give everyone a pony, yeah, I understand your position.
- lotsofpulp 7y ago
  I’m not as knowledgeable about technical specifications as you are, but in my experience when I buy and use X Mb symmetric fiber connection, I actually get it all day every day, and I get it with sub 10ms or 5ms pings, and I have no problem streaming high def movies, multiple simultaneous FaceTime video calls, and downloads. When I use Comcast (and I’m sure all other coax internet providers are the same, at least for residential users), what’s advertised is some nonsense like 200Mbit, but the upload is never mentioned because it sucks, and you only end up downloading things at a few Mbit anyway. Ping times are frequently in the hundred milliseconds, and multiple simultaneous streams/Facetime video/video games will slow everyone down. In my mind, the 200Mbit Comcast is advertising is bullshit, at least since I know what a real 200Mbit up and down fiber connection feels like.

rayiner 7y ago

> It’s only a zero-sum game when their network is at 100% capacity. If they were playing games to optimize usage at peak times I might not care (although they should increase capacity in that case) but when they do this at 5AM it’s clearly bullshit. I don't know exactly how PowerBoost works. I'm going off the description in the article you linked. The article says that PowerBoost uses up excess capacity on the network when it's available. It follows that you can't PowerBoost everybody, even at non-peak times, without lowering the maximum amount of boost. > I don’t understand why you’re carrying Comcast’s water here. Nobody else does this nonsense. No offense, but to most people on HN the physical network is an abstraction that magically delivers bits from point A to point B, and they say crazy things like "networks shouldn't be oversubscribed." I spent my engineering career sitting around layers 2/3, so reading this stuff tends to put me into rant mode.

mikeash 7y ago
The article I linked is a PR piece. Don’t get technical details from it. I linked to it just to show how they’re proud of their bullshit. Here’s some better info: https://www.dslreports.com/faq/14520 https://www.dslreports.com/faq/14520 Relevant quote: “PowerBoost provides bursts for the first 20 MB downloading and the first 10 MB uploading of a file respectively on select Comcast High-Speed Internet services.” Surely you admit that there is no sensible technical reason for a magic 20MB per-file limit on this.
- rayiner 7y ago
  I can think of one important technical reason: you can do a magic per-file limit without having global knowledge about network conditions. Imagine you're an edge router or switch. It's easy to do rate limiting--you just use a token bucket to drop packets above the rate the user pays for. It's also easy to just push packets into the core network as fast as you can, and let congestion control deeper in the network even things out. Neither of those gets you the behavior you want, which is that even when the relevant route is at capacity, a user who starts a new connection will temporarily get a disproportionate share of the capacity compared to users who are doing downloading or streaming. A per-connection boost with a set limit approximates that behavior. Send packets as fast as you can for the first 20MB, then rate limit to the purchased bandwidth. By contrast, how do you implement your proposal? You could dynamically allow each connection to pump packets as fast as it can unless the network was congested, in which case you transition to allowing each user a burst. But you don't really know the network is congested, especially at the edge, and particularly at layer 2, where this rate-limiting tends to happen.
  - mikeash 7y ago
    Ok, so this is a highly intelligent and definitely user centric improvement to their network, and the only reason nobody else does it is because Comcast patented it. And the fact that the limit matches the amount of data used by popular speed testing services at the time is a total coincidence. Cool, hooray for Comcast! I sure wish Verizon would take some lessons from them!
    - rayiner 7y ago
      It would be one thing if it just helped on speed tests. But it also produced real-world benefits for things like web page downloads, MP3 downloads, PDF downloads, etc. It was an easy to implement hack that delivered real benefits for users. I don't see how it warrants so much sarcasm. Again, I think this goes back to forgetting that networks involve real systems engineering. This is real infrastructure--some guy stringing wires on a poll or stuffing Ethernet switches onto a rack. If you're approaching it from the mindset that it's some abstraction where you can just turn a dial and give everyone a pony, yeah, I understand your position.
lotsofpulp 7y ago
I’m not as knowledgeable about technical specifications as you are, but in my experience when I buy and use X Mb symmetric fiber connection, I actually get it all day every day, and I get it with sub 10ms or 5ms pings, and I have no problem streaming high def movies, multiple simultaneous FaceTime video calls, and downloads. When I use Comcast (and I’m sure all other coax internet providers are the same, at least for residential users), what’s advertised is some nonsense like 200Mbit, but the upload is never mentioned because it sucks, and you only end up downloading things at a few Mbit anyway. Ping times are frequently in the hundred milliseconds, and multiple simultaneous streams/Facetime video/video games will slow everyone down. In my mind, the 200Mbit Comcast is advertising is bullshit, at least since I know what a real 200Mbit up and down fiber connection feels like.