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Comment by richbhanover | Hacker News Reader

Yes, but... A "bottleneck" occurs wherever there is a high speed link going to a lower speed link. In your case, the 100 Mbps Ethernets in your home feed through the router to the 1 Mbps upstream your ISP provides. That's another bottleneck.

At this point in a conversation, I always recommend people measure their actual network, to see if they're happy with the situation. If it's good, then everyone's happy.

What results to you get from the DSLReports Speed Test (www.dslreports.com/speedtest)? It measures latency (lag) during the download and upload parts of the test, and will show if your router (or your ISP's router) is buffering too much data, and giving you undesired latency. Best regards.

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The 100 Mbps is from the router to the modem. There is no such thing as a 1 Mbps "link" to an ISP. That bottleneck is imposed by traffic shaping on the ISP's router and nowhere else. (An exception would be something like ADSL, where the uplink truly is the bottleneck. But even then, the queue builds up in the modem, NOT the router!)

Here's a picture, since you seem to be ignoring my words:

     150 Mbps WiFi
           |
      home router
           |
    100 Mbps Ethernet
           |
         modem
           |
    152/81 Mbps DOCSIS
           |
    +-ISP router-----------------+
    |      |  <-- QUEUE          |
    | 3.5/1 Mbps traffic shaping |
    |      |  <-- QUEUE          |
    +------|---------------------+
           |
     10 Gbps fiber (or whatever)

Or, in the case of ADSL:

     150 Mbps WiFi
           |
      home router
           |
    100 Mbps Ethernet
           |
         modem
           |  <-- QUEUE
     8/1 Mbps ADSL
           |
    +-ISP router-----------------+
    |      |                     |
    | 3.5/1 Mbps traffic shaping |
    |      |  <-- QUEUE          |
    +------|---------------------+
           |
     10 Gbps fiber (or whatever)

In either case, neither queue builds up in the home router -- that is exactly the problem, since we can't control the queue size in the modem or ISP! But by traffic shaping to 3.25/0.85 Mbps in the home router (either manually or automatically with fq-codel), we force the queues to build up there, thus giving us control.

> In either case, neither queue builds up in the home router -- that is exactly the problem, since we can't control the queue size in the modem or ISP! But by traffic shaping to 3.25/0.85 Mbps in the home router (either manually or automatically with fq-codel), we force the queues to build up there, thus giving us control.

YES! I understand what you're saying. (I had been treating the cable/DSL links and their terminating equipment as a black box; your description was being far more specific. Thanks for sticking with me to make yourself clear.)

And as you point out, the fix in all cases (at least, until our ISPs get serious about solving bufferbloat) is to force the home router to take control of the buffering by shaping the traffic a bit below the actual link speed. Thanks.

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