3 ms·

They ignore QoS tagging from non-Comcast devices, FYI. I've tried that trick of tagging all my traffic as DSCP 30 (Flash High), and it gets reset to 0 (Best Ef

They ignore QoS tagging from non-Comcast devices, FYI. I've tried that trick of tagging all my traffic as DSCP 30 (Flash High), and it gets reset to 0 (Best Effort) as soon as it crosses the head-end. This is unfortunately also commonplace for providers and an annoyance to businesses in our new post-pandemic world where they need to appropriate tag collab/voip traffic and it gets reset along the way. Lumen (formerly Level 3) often resets to best effort as soon as you cross into their transit edge from your ISP. These values often do not get carried across peering relationships. QoS across the Internet is not guaranteed. In the case I'm talking about, it really only matters how Comcast's network treats their direct customers, not how you get treated after, and they absolutely ignore customer QoS (at least on residential links).

jandrese 3y ago
That makes me wonder how it can distinguish between a Comcast and non-Comcast device on the network. If this were built into the Cable Modem it would be reasonably doable, but if it's a separate box entirely I'm not sure.
- tristor 3y ago
  The CPE (Customer Premise Equipment) /is/ the cable modem, as well as a WiFi router. Another thing it does is provide an authenticated SSID for WiFi that is available to other Comcast customers and utilized to boost coverage for Comcast's mobile offerings, via built-in WiFi profiles. The basic understanding I have is that you get free "unlimited" with the Comcast CPE, because they got sued and lost due to the provided authenticated WiFi being used by other customers to utilized what would otherwise be part of your data cap, so they had to lift the cap when they provided the equipment. Since your own equipment doesn't provide the Xfinity WiFi SSID, you must pay to lift the cap. I did a quick search and couldn't find what I was looking for, but it looks like in 12 states they were prevented until 2022 for enforcing the data cap, and there's a pending class action suit in California related to the WiFi impact on data caps: https://topclassactions.com/lawsuit-settlements/lawsuit-news/comcast-hit-class-action-xfinity-public-wi-fi/ https://topclassactions.com/lawsuit-settlements/lawsuit-news... Anyway, that's my understanding. The net-net is I coughed up the $30/mo because I have no alternatives to Comcast (even at lower speeds) because my landlord has an exclusivity contract with them, and I don't want their shit-tier CPE anyway, especially throttling my traffic and broadcasting a WiFi SSID I don't control. My entire network is proper SME enterprise-grade rackmount gear and I have WiFi 6E throughout my house that is secured to only allow devices I control/allow to connect.
  - mindslight 3y ago
    So correct me if I've misunderstood, but you originally said "customer hostile QoS" which would imply traffic shaping being done on the CPE router, say perhaps with the goal of decongesting the cable segment. This comment you've seemed to walk it back saying the problem with their CPE is that it facilitates service to other customers. If that second thing is really the only problem, then couldn't you just stick their CPE in a Faraday cage and/or unplug its antennas? Also if they are doing traffic shaping, where does the default unclassifiable (eg VPN) traffic fall? It should be easy enough to get an unlimited VPS at a close enough data center and relegate Comcast to a dumb pipe (as they should be).
    - jandrese 3y ago
      I don't think it does sophisticated traffic classification. It's just a way for Comcast to say "you've used more than 10GB of traffic this month, all of your packets get sent down to the best effort Thunderdome until the next billing cycle".
      - mindslight 3y ago
        That conflicts with OP's description saying their Steam downloads were 20% slower, which presumably was tested before hitting any soft transfer cap. I'd guess the goal of traffic shaping on CPE would be to keep upload bandwidth on the cable segments less congested. Or perhaps conntrack is easier to do in a distributed manner?
      - seanp2k2 3y ago
        I wonder how Hulu streaming traffic is QoS'd on Comcast. Someone should check that out and file a lawsuit.
    - tristor 3y ago
      I haven't walked anything back, thank you. There's more than one bad thing Comcast does to their customers, we haven't got close to enumerating the full list. The two issues with the CPE are orthogonal to one another. Whether or not they lift the cap, they still perform traffic shaping when using their CPE (they also perform shaping /without/ their CPE, but it's much cruder).

jandrese 3y ago

That makes me wonder how it can distinguish between a Comcast and non-Comcast device on the network. If this were built into the Cable Modem it would be reasonably doable, but if it's a separate box entirely I'm not sure.

tristor 3y ago
The CPE (Customer Premise Equipment) /is/ the cable modem, as well as a WiFi router. Another thing it does is provide an authenticated SSID for WiFi that is available to other Comcast customers and utilized to boost coverage for Comcast's mobile offerings, via built-in WiFi profiles. The basic understanding I have is that you get free "unlimited" with the Comcast CPE, because they got sued and lost due to the provided authenticated WiFi being used by other customers to utilized what would otherwise be part of your data cap, so they had to lift the cap when they provided the equipment. Since your own equipment doesn't provide the Xfinity WiFi SSID, you must pay to lift the cap. I did a quick search and couldn't find what I was looking for, but it looks like in 12 states they were prevented until 2022 for enforcing the data cap, and there's a pending class action suit in California related to the WiFi impact on data caps: https://topclassactions.com/lawsuit-settlements/lawsuit-news/comcast-hit-class-action-xfinity-public-wi-fi/ https://topclassactions.com/lawsuit-settlements/lawsuit-news... Anyway, that's my understanding. The net-net is I coughed up the $30/mo because I have no alternatives to Comcast (even at lower speeds) because my landlord has an exclusivity contract with them, and I don't want their shit-tier CPE anyway, especially throttling my traffic and broadcasting a WiFi SSID I don't control. My entire network is proper SME enterprise-grade rackmount gear and I have WiFi 6E throughout my house that is secured to only allow devices I control/allow to connect.
- mindslight 3y ago
  So correct me if I've misunderstood, but you originally said "customer hostile QoS" which would imply traffic shaping being done on the CPE router, say perhaps with the goal of decongesting the cable segment. This comment you've seemed to walk it back saying the problem with their CPE is that it facilitates service to other customers. If that second thing is really the only problem, then couldn't you just stick their CPE in a Faraday cage and/or unplug its antennas? Also if they are doing traffic shaping, where does the default unclassifiable (eg VPN) traffic fall? It should be easy enough to get an unlimited VPS at a close enough data center and relegate Comcast to a dumb pipe (as they should be).
  - jandrese 3y ago
    I don't think it does sophisticated traffic classification. It's just a way for Comcast to say "you've used more than 10GB of traffic this month, all of your packets get sent down to the best effort Thunderdome until the next billing cycle".
    - mindslight 3y ago
      That conflicts with OP's description saying their Steam downloads were 20% slower, which presumably was tested before hitting any soft transfer cap. I'd guess the goal of traffic shaping on CPE would be to keep upload bandwidth on the cable segments less congested. Or perhaps conntrack is easier to do in a distributed manner?
    - seanp2k2 3y ago
      I wonder how Hulu streaming traffic is QoS'd on Comcast. Someone should check that out and file a lawsuit.
  - tristor 3y ago
    I haven't walked anything back, thank you. There's more than one bad thing Comcast does to their customers, we haven't got close to enumerating the full list. The two issues with the CPE are orthogonal to one another. Whether or not they lift the cap, they still perform traffic shaping when using their CPE (they also perform shaping /without/ their CPE, but it's much cruder).