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New Comcast Throttling System 100% Online
Comcast tells us new network management system live in all markets
by Karl Bode 12:27PM Monday Jan 05 2009 Tipped by FFH5 See Profile
In line with their traffic management website Comcast has confirmed to us they've installed their new broadband throttling system across all markets. The system, which we first profiled back in September, throttles a user's connection if a particular CMTS port is congested, and if that user has been identified as a primary reason why. This two-condition throttling system replaces Comcast's old, FCC-criticized system of using forged TCP packets to throttle upstream P2P services for all users, regardless of consumption.

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According to Comcast's filings (pdf) with the FCC, they've deployed new hardware and software close to the company's Regional Network Routers (RNRs). This hardware will flip a user from the standard "Priority Best-Effort" traffic (PBE) to lower quality of service (QoS) "Best-Effort" traffic (BE) for fifteen minutes if they're a major reason congestion exists.

While certainly a slightly more transparent system to those paying attention, the new system is probably going to confuse the American public, many of whom don't even know what a gigabyte is. Comcast used a bus metaphor to explain the difference between best effort and priority best effort traffic to the FCC:
If there is no congestion, packets from a user in a BE state should have little trouble getting on the bus when they arrive at the bus stop. If, on the other hand, there is congestion in a particular instance, the bus may become filled by packets in a PBE state before any BE packets can get on. In that situation, the BE packets would have to wait for the next bus that is not filled by PBE packets.
Comcast says that sustained use of 70% of your up or downstream throughput triggers the BE state, at which point you'll find your traffic priority lowered until your usage drops to 50% of your provisioned upstream or downstream bandwidth for "a period of approximately 15 minutes." A throttled Comcast user being placed in a BE state "may or may not result in the user's traffic being delayed or, in extreme cases, dropped before PBE traffic is dropped."

Note that upstream and downstream bandwidth are managed separately. Also note that the differentiation between PBE and BE traffic occurs in two millisecond increments. According to Comcast, even if the packets for a best effort throttled user missed 50 "busses," the delay would only be about one-tenth of a second.

In addition to the new throttling system, Comcast has also a 250GB monthly usage cap for all users. As we mentioned last Friday, Comcast has confirmed that a web portal-based bandwidth tracker is currently in beta among Comcast employees -- but has yet to give an official launch date. A Comcast insider had previously given us leaked screenshots of the monitor, and said it was originally scheduled to go live on January 5 (today).

Comcast has confirmed to us that they've completed the upgrade to the new system.

163 comments .. click to read

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Yarmouth Port, MA

2 recommendations

reply to hottboiinnc

Re: WOW, Cheap bastards

said by hottboiinnc:

They never had this until people started bitching about the invisible cap that they had. And one person thought they should sue Comcast well that person posts on here and you can thank them for all their hard work because now you're getting hit by it.

Don't like it.Take it up with that person and not with Comcast.
Yep, who is that asshat, anyway? Damn him!
Robb Topolski -= funchords.com =- Hillsboro, Oregon -- KJ7RL
What you do at Christmas does not matter so much; What counts are the Christmas things you do all year through.

Got Helix?
Putnam, CT

2 recommendations

reply to Matt3

Re: Can't wait...

said by Matt3:

said by dadkins:

said by swintec:

Can't wait to see the Comcast forums filled with folks who can not figure out why there speeds are so up and down.
Porn in waves?

I'm sure most people will still be finished before the Powerboost time limit is reached.
Leave Dadkins out of this.
"So, Lone Star, now you see that evil will always triumph because good is dumb."

Have you been touched by his noodly appendage? »www.venganza.org


Rockville, MD

2 recommendations

reply to Lazlow

Re: Why both?

so you can't get your video from the internet. they don't want competition with their video offerings.

it would appear the throttling makes continuous viewing of streaming HD video potentially painful, if not impossible (what is the "sustained use" time period?).

the caps take care of things if you like to download your HD for later viewing.

it's preemptive, anti-competitive behavior to discourage people from getting their video from the internet instead of paying comcast.

Philadelphia, PA

2 recommendations

Yup, We're Done...

We've contacted Comcast and are awaiting confirmation that the system has been 100% implemented across all markets, and will update this entry.
Yup, we sure did finish. It was a huge amount of work in 90 days, but it's all done.



Saint Louis, MO

2 recommendations

Why both?

Why both this throttling and the cap? Assuming the throttling works the way it is supposed to, I really do not have much of a problem with it (mostly just the principle of the thing). They have always said that the caps were to prevent one user from slowing down the rest of the users on the node. This type of throttling should prevent that. So why the cap?