Hello everyone. I wanted to ask if anyone running DOCSIS3.0 could provide some insight on how they setup 65+Mbps downstream service flows. Typically what I do is provision the CM config file to be ~10% higher than the advertised speeds, so for 50Mbps advertised service I provision 55Mbps. I'm just not sure how well this will scale. Our company want to offer two higher tiers than we do now(our highest is 50Mbps). I've been asked to build 65Mbps and 80Mbps. I have only what's required in the CM config file for the service flow, everything else is default settings. I typically don't have problems getting the provisioned speeds but sometimes I cannot sustain what the SfMaxTrafficRate is configured for. When looking at throughput graphs(in 100ms intervals) I see throughput hit 70Mbps for a few seconds, then drop down to ~20Mbps for a second, then ramp back up to 70Mbps.
DownstreamServiceFlow =
SfReference = 101
SfQosSetType = 7
SfTrafficPriority = 1
SfMaxTrafficRate = 71500000
I use Arris PacketACE for my config files and noticed 3 setting which could impact downstream throughput. SfMaxTrafficRate, SfMaxTrafficBurst and SfDownstreamPeakTrafficRate. PacketACE is pointing me to the DOCSIS specs so I'm about to start reading though that. But, I was wondering how other folks are setting up their high speed DOCSIS tiers? Do you change SfMaxTrafficBurst or SfDownstreamPeakTrafficRate in your config files outside of the defaults?
TIA
-Matt
Hi,
How exactly are you measuring speed? SNMP from DS/MAC interface or...?
We have speeds of 50, 100, and 150 (for testing purposes) and I always change just the MaxRateSustained (SfMaxTrafficRate in your example I guess), but I never ran speed test with such resolution (100ms). Increasing the burst can decrease the overhead but I don't think that any of these parameters should cause the constant drop in speed for that long (1sec).
For downstream, you only need to set the max-rate
For 65Mbps I would set this to be 65 * 1024000 = 66560000
If you want to use "powerboost" functions, then you can use two other settings :
peak-rate (what the burst speed will be) eg 100Mbps
max-burst (how big the bursts can be) eg 4MB
But I reckon these were more useful for slower speed plans (eg 2Mbps burst to 10Mbps), where they would help make bursty traffic like web browsing work much better. Customer could click a URL and page would load at the peak-rate. But if customer downloads a file, the speed would drop back to max-rate soon after the download starts. With these higher speeds 50Mbps+, then I don't think the customer is really going to notice much difference if you provision bursts to say 100Mbps.
If you don't want to allow any bursting then just setting the max-rate should work fine. And customers should be able to achieve these speeds as long as you have sufficient bandwidth / bonding-groups available on the CMTS. No other special tuning needed.
Thanks guys for the clarifications. That helped a lot.