[Cake] overhead and mpu

Dennis Fedtke dennisfedtke at gmail.com
Tue Sep 5 16:19:40 EDT 2017


Thank you for all answers.
But for me this still makes no sense.
Assuming we have an ethnernet connection running over a docsis line.
docsis is able to transmit full 1500byte ethernet packets.
Lets say it is an 50 Mbit/s Line. (I dont know now how exactly docsis works)
So to reach the 50Mbit/s ethernet speed the docsis link rate needs to be 
higher 50,6 Mbit/s (50*1518/1500 ??)
But when running a speedtest it will still not show the full speed. 
because of other overhead from underlying protocols (tcp/ip for example)
So the ISP will set the sync rate even higher to compensate for that.

But does this matter for the end user?
In case of docsis does it make sense to account for 18 overhead?
The user will enter 50mbit and it will work. If the isp has provided a 
sligher higher syncrate.

and the mpu setting. i don't know how cake handles this in detail.
How the overhead gets added.
lets i enter mpu 46.
And cake we set 18 as overhead.
Will this result in mpu 46 or 64?
Can someone debug the code maybe please? :>
I have the feeling with mpu 46 my pages lot a bit snappier. but could be 

Thank you.

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