jfmezeiPremium
join:2007-01-03
Pointe-Claire, QC
kudos:22 Reviews:
 ·ELECTRONICBOX
| How does "Speedboost" actually work ? Does anyone know how the temporary speed increases on DOCIS modems deployed by some cable companies actually works ?
Is this part of the modem's firmware which automatically raises the rate limit for X minutes when it sees you have hit the standard rate limit ?
Or does the CMTS control this by sending some command to the modem to boos the speed and then sending another command later to return speed to normal ?
Or is it done in another way ? |
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| Re: How does "Speedboost" actually work ? I imagine there's different ways to do it. Might not be the same for all cable companies. |
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Reviews:
 ·linode
 ·Cogeco Cable
·Bell Sympatico
| reply to jfmezei
I seem to remember a few config parameters on a CMTS that I played around with like this:
- max-rate was a value in bits/s that is the subscriber's speed (that they pay for).
- max-burst was the value in bits that was the "cap"; any data stream transmitted over this amount would be throttled back to max-rate
- peak-rate the rate limit of the burst speed, could be 0 to allow for max. possible speed
So, for instance, if you paid for 20 Mb/s service that allowed 80Mb of burst up to 50Mb/s, it could be something like this:
max-rate 20000000
max-burst 80000000
peak-rate 50000000
Things may have changed, I'm not sure, but I believe that it's all on the CMTS side. All I could find from a brief look through my Cisco docs was information on upstream bursts, which have to do with the number of time divisions that a modem is allowed to send upstream data to the CMTS for. Nothing on downstream. I'll keep looking. |
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jfmezeiPremium
join:2007-01-03
Pointe-Claire, QC
kudos:22 | Are these CMTS parameters something which are used to build the provisioning profile sent to the modems via TFTP, or is this something which the CMTS uses itself to rate limit traffic for each individual customer ? |
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Reviews:
·linode
·Cogeco Cable
·Bell Sympatico
| said by jfmezei:Are these CMTS parameters something which are used to build the provisioning profile sent to the modems via TFTP, or is this something which the CMTS uses itself to rate limit traffic for each individual customer ?
The latter. The CMTS I worked with (Cisco) had QoS profiles into which these parameters would be saved, and different QoS profiles could apply to different CMs. |
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jfmezeiPremium
join:2007-01-03
Pointe-Claire, QC
kudos:22 Reviews:
·ELECTRONICBOX
| I had always thought that the speed was downloaded onto the modem.
When videotron had begun to mess with me by claiming I was under contract when I wasn't, and wanted to increase my monthly rate by $10, I decided to find another ISP. During this time, I had my subscription reduced to the lowest priced one without contract (which result in net drop in Videotron's revenues from me).
I was able to maintain my old speed for a couple of weeks until a power failure at which point the modem rebooted and I really felt the speed decrease kick in. |
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| Well the speed is downloaded by the modem over TFTP, but I believe the boost is something negotiated between the CM and CMTS. |
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 hm
@videotron.ca | reply to jfmezei
What are the speeds of this few seconds of "speed boost"?
Are they all the same?
Different for each speed tier? |
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 nitzguyPremium
join:2002-07-11
Sudbury, ON
·TekSavvy DSL
| reply to jfmezei
said by jfmezei:I had always thought that the speed was downloaded onto the modem.
When videotron had begun to mess with me by claiming I was under contract when I wasn't, and wanted to increase my monthly rate by $10, I decided to find another ISP. During this time, I had my subscription reduced to the lowest priced one without contract (which result in net drop in Videotron's revenues from me).
I was able to maintain my old speed for a couple of weeks until a power failure at which point the modem rebooted and I really felt the speed decrease kick in.
It is set at the modem. During the provisoning process the modem says "Hey I'm 00:xx:yy:zz:aa:bb, I believe you have a CM file for me" to the CMTS. the CMTS looks it up and goes "Yup, here's what you get" and the file is downloaded to the Cable modem.
Those parameters will be in the cable modem. Typically these will not be pushed to the modem unless as you saw it loses power and is power cycled. In this case though Videotron could have remotely rebooted your modem which I'm surprised they weren't set up to do when they changed your profile.
Perhaps its a manual process to reboot your modem for them, or maybe it was at the time. When I was at Cogeco it was an automated process and the user saw the new speeds instantly as the modem was rebooted and the new config file was pushed down to the modem.
The boost is in the CM file. It may be negotiated simply based on TDMA timeslices that are available from the CMTS to be able to "boost" the speed...in essence if there are free slots available, to simply use all of those slots to move your data down...
HTH. |
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