So we all have 4 channels going by wikipedia thats 122.88 (108) Mbit/s let say Docsis does its best evenly balancing the traffic over the channels and that the area is in good health for everyone at QAM64.
Lets talk TCP it helps that it slows down when going to fast this is a good thing what harms the network is a DoS its not going to say ooh sorry was I going to fast? Let me slow down.
Let say VM QoS/BWM after Docsis for the upstream at 80Mb let say only four people on them channels are uploading with a upto limit of 50Mb each would be limited to 20Mb and this works fine add another person thats 16Mb. But lets say four people plus a DoS from a fifth at 50Mb and this I where things get messy you see the QoS/BWM takes the five people traffic as 16Mb each limiting with the DoS being dropped hard but this does not stop Docsis from trying get the Data from the modems causing the thing we hate over utilisation as it buffers.
So in short QoS/BWM needs to be done at the Docsis level but does QoS/BWM after docsis help? Yes does it solve the issue No.
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