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How to calculate the appropriate value of Maximum Traffic Burst in docsis file

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deividfiguer
How to calculate the appropriate value of Maximum Traffic Burst in docsis file

Hi

I am configuring new bandwidths in the docsis files and I want to know what values ​​you recommend to put in the Maximum Traffic Burst parameter for 50Mb of Downstream and 8Mb of Upstream

Please tell me if you use any formula to calculate the appropriate value to configure of Maximum Traffic Burst

This is an example of the values ​​I am using.

Network Access Control:on
Privacy Enable:on
Upstream Service Flow Encodings
Service Flow Reference:1
Quality of Service Parameter Set:provisioned admitted active
Traffic Priority:0
Upstream Maximum Sustained Traffic Rate:8192000
Maximum Traffic Burst:80000
Downstream Service Flow Encodings
Service Flow Reference:2
Quality of Service Parameter Set:provisioned admitted active
Traffic Priority:0
Downstream Maximum Sustained Traffic Rate:51200000
Maximum Traffic Burst:10000
Maximum Number of CPEs:4

I am awaiting your comments

best regards, happy new year

kwesibrunee
What are your goals for

What are your goals for increasing the Max traffic sustained rate?

1: make speed test results show provisioned speed plus maybe a little extra?

set your peak sustained rate 5-10% over you max sustained rate
size your max traffic burst so that you have ~20 secs of sped up bandwidth

e.g.
DS 50 meg service
max sustained rate 50000000
peak sustained rate 60000000

to get 60 megs for 20 secs with a provisioned speed of 50 megs you need a max traffic burst capable of holding 10 megs for 20 secs

10,000,000 * 20 = 200,000,000

this is in bits so convert to bytes
200,000,000 / 8 = 25,000,000

so to sustain 60 megs on the downstream for the duration of a speed test (I used speedtest.net) you need a max traffic burst of 25 MB

2: get small traffic off the network as fast as possible?

the idea here is to get sporadic traffic (web site visit, email check) through the network as soon as possible

The Average Desktop Website in 2021 is 2038.4 kb per google https://www.google.com/search?q=average+website+size+in+bytes+2021&biw=1...

here you set the max traffic burst to the size you want say lets round up to 3 MB
and you don't set the peak sustained rate

this way when doing sporadic browsing websites will load at the line speed of whatever docsis bonding the modem has, for 4 channel modems this is about 150 megs, 8 channel 300 megs and so on. Obviously, this would only use bandwidth that was available on the shared channel. The idea is to get the traffic to the customer as soon as possible for the casual user. Making the user experience a quick as possible.

this will make speed test show an initial spike while max burst is used up and then will settle at max sustained rate.

If you have a different goal in mind please share and I will try and help you optimize it.

deividfiguer
How to calculate the appropriate value of Maximum Traffic Burst

Hi

My intention is that the user has a fast navigation for all cases (Website, Youtube, Netflix) and when he does the speed test, it shows the assigned speed

Taking your recommendation, I will increase 5% to each of these values of Maximum Sustained Traffic Rate ​​to improve the perception in the speed test.

before:
50Mb = 5.120.0000 KB
8Mb = 8.192.000 KB

after 5% increase:
50Mb = 53.760.000 KB
8Mb = 8.601.600 KB

I want to understand the formula that I must use to calculate the appropriate value of Maximum Traffic Burst to have a fast navigation for all cases and when I do the speed test, have a formula that allows me to calculate the value for future plan configurations

Please help me to have the best and correct configuration of Maximum Traffic Burst depending the value of Maximum Sustained Traffic Rate

I want to create configurations of 20,30,40,50 Mb of Downstream and 5,6,7,8 Mb of Upstream

Thanks for your valuable help

regards

kwesibrunee
Unfortunately, you have to

Unfortunately, you have to pick one or the other or do some very creative things

if you set a max burst of any size and no peak rate, the modem will use up the max burst bytes as fast as possible resulting in a quick burst of speed in seconds/micro seconds, when max burst bytes have been transferred the speed will go down to normal rate. This helps with bursty traffic like Web browsing, email etc... However for sustained file transfers like youtube/netflix or speed tests it does little because the max burst bytes are used very quickly and the connection needs to be idle for them to recharge.

On the other hand if you set a max burst and a peak rate, the modem will transfer data at the higher rate (fixed value) until it uses up all of the max burst bytes. This helps for short duration speed tests as they typically last 20-30 secs in each direction, you can use the formula I provided originally to calculate how much max bytes to set to maintain a higher speed for the duration of the speed test. For large file transfers or Youtube/Netflix this provides 30 secs of fast bandwidth then back to your nominal speed.

there are other alternatives to make things smoother but they all have their downsides too.

1) if you have a locally hosted speedtest you can create a secondary flow and classifier and set up the long duration max burst / peak rate. Down side is people can speed test while doing other things and while they will still get a consistent speed, it cause issues with utilization since they will be using more traffic. i.e. with a secondary service flow you could be watching Netflix at 50 Mbps and speed testing at 50+ megs a sec.

2) You could use a video cache, Netflix has a cache, and you could use a 3rd party one like Qwilt for other services. This works well but has cost and complexity.

3) what a lot of people do is add 5-10% to max sustained rate so that speed tests show advertised rate, works best with a locally hosted speed test, and then set max burst without peak rate so that web browsing is super fast. This works with small 10-15 MB max burst on every speed tier. This is the most likely to keep most people happy and only downside is 5-10% extra potential traffic.

deividfiguer
How to calculate the appropriate value of Maximum Traffic Burst

Hi

Thanks for your answer, according to this I must configure between 10 or 15 Mb the Maximum Traffic Burst

Taking into account that Upstream Maximum Sustained Traffic Rate values ​​between 4 and 8 Mb, what values ​​in this case do you recommend of Maximum Traffic Burst?

regards

mbowe
Good post!

Good post kwesibrunee!

And if on Cisco platform, you must also enter the global command "cable ds-max-burst" to active this DS "powerboost" functionality

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