M-CMTS Band-sharing ( remaining ratio ) | docsis.org

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M-CMTS Band-sharing ( remaining ratio )

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konkordia
M-CMTS Band-sharing ( remaining ratio )

I have question about Docsis2.0/3.0 traffic sharing.

I have in config ( rest cutted )
-------------------------------

interface Modular-Cable1/0/0:0
cable rf-bandwidth-percent 20 remaining ratio 100

interface Modular-Cable1/0/0:1
cable rf-bandwidth-percent 20 remaining ratio 100

interface Modular-Cable1/0/0:2
cable rf-bandwidth-percent 20 remaining ratio 100

interface Modular-Cable1/0/0:3
cable rf-bandwidth-percent 20 remaining ratio 100

interface Wideband-Cable1/0/0:5
cable rf-channel 0 bandwidth-percent 30 remaining ratio 100
cable rf-channel 1 bandwidth-percent 30 remaining ratio 100
cable rf-channel 2 bandwidth-percent 30 remaining ratio 100
cable rf-channel 3 bandwidth-percent 30 remaining ratio 100

-------------------------------

From this config

Docsis 2.0 on ie Modular 1/0/0:0 :
guaranted 20 % of band
PIR up to 70 % of band because ( 20 + 30 are guaranted ) remaining is 50 % of band

Docsis 3.0 on ie Modular 1/0/0:0 :
guaranted 30 % of band
PIR up to 80 % of band because ( 20 + 30 are guaranted ) remaining is 50 % of band

Am I correct ?
Any comments ?

mbowe
Looks ok to me

I reckon you are correct.

The cisco docs are a bit sketchy on this whole topic. It would be great if they provided a few more examples!

Its possible to just run bandwidth-percent 1 remaining ratio 100 for every interface, which lets the bandwidth be shared around between narrowband/wideband based on demand. But then you can run into trouble if you have any flows that have min-rate or max-latency requirements.

Min-rate type traffic goes into the CIR queue. The total amount of this traffic needs to fit into the "rf-bandwidth-percent x" amount you have nominated. CIR traffic is serviced first and then BE traffic gets access to whatever is left over, shared out by priority.

max-latency traffic goes into the LLQ queue. Again such traffic is dealt with before BE gets a look in.

If you are playing around with these different types of traffic and dynamic bandwidth sharing, here's a couple of useful commands :
"show int integrated|modular|wideband cable x/x/x:x downstream" shows you the total downstream bandwidth plus reserved/reservable. (Reservable is 80% of the total)

"show cr10k cable x/x/x queue" shows you the available/reservable bandwidth, plus also breaks down the queues into BE, CIR, LLQ for each attached integrated|modular|wideband

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