The CMTS assigns the cable modem a SID during registration. The configuration file may contain addition static service flows as desired by the cable operator. For example one North American MSO assigns a small 10 kbps service flow per cable modem to ensure that digits dialed on eMTAs for phone calls get a quality of service (QoS). But in most cases additional service flows are assigned dynamically through DSC and DSA messages as you suggested. This is often handled by PacketCable to help ensure an added level of security and integration with other devices. The SFIDs are then torn down at the end of the needed activity, say a phone call, so that the SFID and bandwidth can be used later when needed.

-Brady

Always good to hear from you and a Happy New Year to you as well.

You are experiencing a very common symptom that many cable operators see. You provision a speed on your DOCSIS network and your subscriber tests those speeds against a server located somewhere out of your control. There are a couple of things to keep in mind and then one recommendation I will make.

1) When you provision your speeds, say 1MB up and 2MB down, keep in mind that those speeds include the IP and DOCSIS overhead which can be as much as 12% depending upon your CMTS configuration and if you have BPI turned on. So it is recommended that you do an internal speed test and then adjust the actual up and down speeds accordingly (say 2.2MB down and 1.1MB up as an example) to ensure actual usable speed are obtained.

2) You will need to educate your subscriber that when they do a speed test to the Atlanta server they are not only testing the speed of the DOCSIS network, but also the speed of the backbone connection from the Bahamas to the States and then to the IP host that is hosting the server. There is no QoS to the server in Atlanta and congestion can skew the speed test results This is when it is very beneficial to have a piece of test equipment that can perform a DOCSIS-only speed test such as those made by JDSU, VeEX and Sunrise Telecom to show results to the subscriber.

Finally, as my suggestion, you can host your own speed test server locally. Companies sell these or you can even build one on a Linux platform and then advertise the test service to your customers who complain about the “Speakeasy” or “Speedtest.net” throughput. If you do this, you are likely better off with a professional looking service such as Ookla so your customers feel their test is valid. This will demonstrate you are offering the service provided at least to your local backbone.

-Brady

Say we are provisioning a certain service offering for 2.0 megs download and 1.0 megs upload. A customer using that offering is on one of our outer islands, say somewhere in the Abacos. They want to see if they are getting what they are paying for; so off they go to a site like Speakeasy (speakeasy.net) and chose the Atlanta test server. and test their “speeds”.

We provision them here in The Bahamas for 2down/1up; what keeps that provisioning in force so that on a distant connection that throughput could be reasonably determined (our Abaco customer would actually see the 2/1 speeds on a server in Atlanta)? I was under the impression that what we would provision our subs would be more relevant in our domain.
By the way work continues on our upgrade to 3.0!!!

Thanks
Alon

You are absolutely correct. Some cable operators will dedicate a small amount of dedicated static service flows (say 10 kbps) for each eMTA. While this is a bit of extra overhead that cannot be used for anything else, it will always ensure that VoIP subscribers will always have a QoS for dialing phone numbers and setting up calls with the Call Management Server (CMS).

Regards,
-Brady

Would you caveat this with the implementation of Service Flow Admission Control as a way to proportion a percentage of b/w dedicated to specific traffic types (voice) during times of high utilization?