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Drizew

join:2004-09-17
Los Lunas, NM

2 edits
reply to Daveid

Re: Comcast announces new bandwidth throttling scheme

I guess I just didn't construct that sentence as well as I should have. It should have read something like this. "By the way, there is absolutely no relation between Comcast lowering your speeds by throttling and powerboost."

Excuse me, I am trying to multi task. Things slip by me from time to time.

Edit: I would like somebody from Comcast to chime in and maybe give us a better idea of how this all works. The analogy in the pdf was decent, but I would prefer to see some raw data. One tenth of a second is hardly a delay in delivery, but I doubt the system works as intended 100% of the time.



JohnInSJ
Premium
join:2003-09-22
Aptos, CA

1 edit

1 recommendation

This is how Comcast's congestion management works

said by Drizew:

Edit: I would like somebody from Comcast to chime in and maybe give us a better idea of how this all works. The analogy in the pdf was decent, but I would prefer to see some raw data. One tenth of a second is hardly a delay in delivery, but I doubt the system works as intended 100% of the time.
The pdf explains the system just fine.
When you are identified as a user that is contributing to congestion on a node (and only if you fall into the "if more than 70 percent of your max bandwidth (downstream or upstream) is used for more than 15 minutes" then your packets will be marked as lower priority for the next 15 minutes. There is no throttling.

Here is a simple metaphor:

You and 10 other people have drain pipes. All 10 drain pipes feed into a single sewer line.

Everyone's pipe can drain 10 gallons per second
The sewer can drain 70 gallons per second.

If all 10 users are draining at 7 gps or less, no problems.

If all 10 users are draining at 7gps, and then you start draining at 8pgs, there is now an extra gallon per second that cannot be drained. water backs up. At first, it backs up equally across all 10 of you, so you get 7.9gps, and everyone else gets 6.9gps. After 15 minutes, your water is made to wait so everyone else's water goes first. You get 7gps, and everyone else does too. If another user drops down to 6gps, you'll get 8gps - your water soaks up EXCESS capacity, but no longer GRABS capacity from other users.

It's not a perfect analogy, but hopefully it helps clarify things.

To recap, you can use 100% of your pipe all day and night (for a few days, anyway, then you'll hit the cap - a whole different ball of wax) as long as the nodes you pass through are not saturated. If they become saturated your packets go to the 'bulk' category - you soak up all the excess capacity of the node, but if someone else needs it, your packets wait.
--
My place : »www.schettino.us

Drizew

join:2004-09-17
Los Lunas, NM

Re: Comcast announces new bandwidth throttling scheme

I understand everything they said in the pdf. I was looking for MORE information. I wanted information/data they have collected since this system has been implemented, not theory or estimates. It would be nice to know how long the systems stay overcrowded once the throttling system is activated. How well has it addressed the problem in the top 5 (bottom 5 technically) overcrowded markets? That is the kind of information I was looking to hear from Comcast. I understand the chances of them releasing any real information is small, but it is worth the effort to ask.



funchords
Hello
Premium,MVM
join:2001-03-11
Yarmouth Port, MA
kudos:6

1 edit

said by Drizew:It would be nice to know how long the systems stay overcrowded once the throttling system is activated. How well has it addressed the problem in the top 5 (bottom 5 technically) overcrowded markets? That is the kind of information I was looking to hear from Comcast. I understand the chances of them releasing any real information is small, but it is worth the effort to ask.
Comcast is currently in a period of technical Glasnost (which we love), and they really do like their latest solution for network management. Ask and they very well may provide some kind of answer.

Fixed uneven quote tags. ~sorto'

--
Robb Topolski -= funchords.com =- District of Columbia -- KJ7RL
Test your Broadband connection today! -- »measurementlab.net/


JohnInSJ
Premium
join:2003-09-22
Aptos, CA

1 recommendation

reply to Drizew

said by Drizew:

It would be nice to know how long the systems stay overcrowded once the throttling system is activated. How well has it addressed the problem in the top 5 (bottom 5 technically) overcrowded markets?
The whole point of the method they implemented was that the system now behaves rationally and fairly, so the only people who would notice it at all would be those who were running full out, for long periods of time, and who happen to be on nodes where there were periods of congestion when they were running full out.

In the time I've been monitoring this forum I have seen may people posting complaining about throttling who were in fact experiencing connection issues, or problems upstream. I've yet to see one instance where anyone actually saw deprioritisation of their packets (which is the only "throttling" you'll ever see.)

Based on the algorithm and the general overcapacity of the comcast infrastructure, I'd bet that fewer then 1 in 100 would ever see it.
--
My place : »www.schettino.us