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Comcast Cheating On Bandwidth Testing?

kdawson posted more than 6 years ago | from the tuning-for-the-benchmark dept.

Networking 287

dynamo52 writes "I'm a freelance network admin serving mainly small business clients. Over the last few months, I have noticed that any time I run any type of bandwidth testing for clients with Comcast accounts, the results have been amazingly fast — with some connections, Speakeasy will report up to 15 Mbps down and 4 Mbps up. Of course, clients get nowhere near this performance in everyday usage. (This can be quite annoying when trying to determine whether a client needs to switch over to a T1 or if their current ISP will suffice.) Upon further investigation, it appears that Comcast is delivering this bandwidth only for a few seconds after any new request and it is immediately throttled down. Doing a download and upload test using a significantly large file (100+ MB) yields results more in line with everyday usage experience, usually about 1.2 Mbps down and about 250 Kbps up (but it varies). Is there any valid reason why Comcast would front-load transfers in this way, or is it merely an effort to prevent end-users from being able to assess their bandwidth accurately? Does anybody know of other ISPs using similar practices?"

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This is an advertised feature I believe (5, Informative)

vacaboca (691496) | more than 6 years ago | (#22473734)

Doesn't Comcast advertise this "SpeedBoost" as a feature - the language in their ads is something like "get massive super speed for the first 10MB of a download, then it will revert to your provisioned line speed"... So, it actually *is* a good thing rather than something to pad bandwidth tests, and it does generally help your general user, right?

Re:This is an advertised feature I believe (5, Informative)

andawyr (212118) | more than 6 years ago | (#22473806)

I agree - I know that Shaw Cable (Alberta) offers a plan that does exactly this: for 5-20 seconds, you get increased download bandwidth. This is their PowerBoost feature, that costs an extra $2.95 above your regular plan....

Re:This is an advertised feature I believe (1)

mrxak (727974) | more than 6 years ago | (#22474730)

Ohhhh. So that's what it is. I keep seeing it on ads but I've never seen it actually explained. I assumed it was just marketing speak pretending to be some feature that didn't really exist.

Re:This is an advertised feature I believe (4, Insightful)

jandrese (485) | more than 6 years ago | (#22473832)

Yeah, the point is that you can get a webpage down in those first few seconds generally so browsing is much better than it would otherwise be.

Re:This is an advertised feature I believe (4, Interesting)

xSauronx (608805) | more than 6 years ago | (#22474040)

This is it, and it should be amazingly obvious to any "sysadmin" who should know something about general browsing habits. I worked for a wISP for a year and this was a standard feature offered by the company for no extra charge. Max subscriber speeds were 1.5 Mbps, but for about 20 seconds ALL traffic was burst to 2 Mbps, regardless of the subscriber paying for the 500 k/s speed or something higher. For general browsing and light email, it made all the customers quite happy to have things terrifically speedy.

Re:This is an advertised feature I believe (5, Interesting)

Ed Avis (5917) | more than 6 years ago | (#22473862)

So... how can you tweak your Bittorrent client to fool Comcast into thinking it is making lots of small downloads?

Re:This is an advertised feature I believe (5, Insightful)

arivanov (12034) | more than 6 years ago | (#22473892)

Torrents do that anyway. That is the reason why comcast have to beat them on the head. Each segment in the download is small enough to fit its "booster" criteria.

Actually, there is nothing wrong with this approach. This means that interactive services and casual browsing are favoured vs bulk downloads. That is what every ISP wants to do anyway.

Re:This is an advertised feature I believe (1, Insightful)

_KiTA_ (241027) | more than 6 years ago | (#22474196)

Torrents do that anyway. That is the reason why comcast have to beat them on the head. Each segment in the download is small enough to fit its "booster" criteria.

Actually, there is nothing wrong with this approach. This means that interactive services and casual browsing are favoured vs bulk downloads. That is what every ISP wants to do anyway.
Yeah, this is exactly what you want as an ISP. Your real customers aren't the college assclowns on Napster / Animesuki / etc, they're the Grandmas wanting to load fast, and the professors wanting their students to be able to load Wikipedia fast enough to do research. (As some overgeneralized examples.)

Broadband, like dialup, is subsidized by the low use casual customers. Come to think of it, so's World of Warcraft, which I wish more of those "ubers" would realize before it's too late.

Re:This is an advertised feature I believe (1)

nbert (785663) | more than 6 years ago | (#22474656)

Broadband, like dialup, is subsidized by the low use casual customers.
In other words the casual user is paying too much. Dialup was actually more fair in this regard, because the more you used it, the more you paid.

A related note: Mail- and webservers usually don't serve content at more than 1 mbit, so all those speedboost features are not that useful at all. Just monitor your bandwith usage when you are retriving lots of mails...

PowerBoost uses a 30 second average, not filesize (5, Informative)

ben there... (946946) | more than 6 years ago | (#22474216)

Torrents do that anyway. That is the reason why comcast have to beat them on the head. Each segment in the download is small enough to fit its "booster" criteria.
No, that's not right.

PowerBoost only accelerates the connection if the average speed you've been getting over the past 30 seconds* is less than the speed you are rated at/paid for. So if you have a 6 Mbps connection, that's 768 KB/s max. PowerBoost will raise that to up to 2 MB/s for a little less than 15 seconds, making your average for the past 30 seconds equal to 768 KB/s. After that, no matter how many new connections you open, your connection stays at 768 KB/s. But if your connection gets interrupted/throttled for a few seconds, you may get another boost after it resumes, until you are back to 768 KB/s 30 second average again.

*it may be slightly more/less than a 30 second average. Boosts seem to last about 10-15 seconds, which would make sense with that number.

Can't be right (5, Funny)

ultranova (717540) | more than 6 years ago | (#22474496)

That can't be right. From your description, it sounds like a genuinely good and beneficial to the user idea. Where's the catch ?

Re:Can't be right (5, Funny)

Tassach (137772) | more than 6 years ago | (#22474616)

Any actually benefit to the customer is purely coincidental and unintentional.

That nice warm shower feels pretty good until you realize someone is pissing on you.

Re:PowerBoost uses a 30 second average, not filesi (1)

NeoTerra (986979) | more than 6 years ago | (#22474542)

Looks like you are getting your 6 Mbps...

768 KB/s * 8 (bits per byte) = 6144, or 6 Mbps.

Since your PowerBoost goes up to 2 MB/s, it would be as follows...

2048 KB/s * 8 = 16384, or 16 Mbps.

Re:This is an advertised feature I believe (0)

Anonymous Coward | more than 6 years ago | (#22474314)

I have optonline and I actually get sustained download rates around 20Mbit even on large iso images.

Re:This is an advertised feature I believe (1)

LordKazan (558383) | more than 6 years ago | (#22473904)

i don't know if you'd have to... because the typical largest block in a torrent is 4meg.. so if you have to init a new connection to the peer for transfer it may work already.

but it's probably only giving you that boost when you start from idle. so write an azureus plugin that batches your transfer starts appropriately.

Re:This is an advertised feature I believe (2, Insightful)

Anonymous Coward | more than 6 years ago | (#22473922)

Doesn't matter if you do.

1) No peer can upload at those speeds
2) If your speeds were that high, Comcast would just cut your connection due to their 'fair use' policy (trust me I know)

Re:This is an advertised feature I believe (0)

Anonymous Coward | more than 6 years ago | (#22473928)

Better yet, turn sideways and run in place, watching the download progress bar as you do. You get the appearance you're moving faster than light!

Re:This is an advertised feature I believe (3, Interesting)

NickCatal (865805) | more than 6 years ago | (#22474414)

There is a 'cooldown' timer. You need to be at very low bandwidth levels for a specific amount of time (or some other measure) before you can 'burst' again.

In chicago it is 12mbps then down to 6 or 8 depending on your plan. To do a proper speedtest on comcast you need to download a 100-200MB file. Although if you are getting 12mbps easily odds are you are getting your rated line speed.

Re:This is an advertised feature I believe (1)

icsx (1107185) | more than 6 years ago | (#22473950)

How it is good thing? If user pays from "insert speed here" he should get that speed full time and not just for first few seconds or 10MB. Client should get what he or she pays for. On the other hand, there is propably that fine print somewhere, like "max speed is 24/1 Mbit/s but works atleast with 1024/256Kbit/s".

Re:This is an advertised feature I believe (4, Informative)

somersault (912633) | more than 6 years ago | (#22474128)

If you read the whole of the comment (don't strain yourself, now), you'd see that the user is in fact paying for "insert speed here", but for a premium they can also get "insert speed here" for the first $size_limit || $time_limit of their download, which *is* a good thing when browsing webpages or other small files.

Re:This is an advertised feature I believe (1)

192939495969798999 (58312) | more than 6 years ago | (#22473952)

If this were true, couldn't you break up downloads into 10 mb chunks and get the equivalent of the high "sustained" speed numbers?

I do remote support, & COMCAST = F A S T!!! (0, Troll)

Anonymous Coward | more than 6 years ago | (#22474030)

Daily, on the job professionally (fixing folks' computer woes via remote support) I see a lot of folks from various ISP/BSP's nationally in the U.S.A. (continental, & offshore like Canadians & Hawaiians)... & I get to "compare" the performances of each:

COMCAST does rank up there with the fastest, IF NOT CONSISTENTLY the fastest overall!

(Judging just by "feel" though, mind you (& it's the MOST important thing really), with myself as the remote desktop support person doing the job on client systems via WEBEX remotely).

Whatever they're doing, imo & experience, they're doing it RIGHT!

Re:This is an advertised feature I believe (3, Funny)

sm62704 (957197) | more than 6 years ago | (#22474032)

There is an old saying "never attribute to malice what incompetence can explain", but come on guys, this is comcast. A snake doesn't bite by mistake.

Re:This is an advertised feature I believe (1)

strredwolf (532) | more than 6 years ago | (#22474064)

They had been for a while, especially with those "High speed" commercials. Not as of late, though.

Re:This is an advertised feature I believe (5, Informative)

ElizabethGreene (1185405) | more than 6 years ago | (#22474176)

You are correct in your interpretation. The customer briefly receives more than they pay for after a period of inactivity, this throttles down to the 'purchased' bandwidth as the activity increases. For Read-Click-Load-Read web browsing this gets content in front of eyeballs quicker and is a "good" thing. If you are using a tiny file for a bandwidth test it screws up the results. HINT: USE A BIGGER FILE.

People are out with pitchforks and torches over the "bad" thing Comcast does, throttling Torrent downloads, which works completely differently. To throttle a torrent, they forge a "I'm dead" packet from remote host, and send it to the customer. This causes the customer's torrent application to shop elsewhere for a feed. The repeated connect-forge disconnect-search-connect process slows the overall transfer. This only works because of the multi-peer technology underlying torrents, and wouldn't work with web browsing or ftp*.

* technically it would reduce the bandwidth usage, because it terminates the connection. This would result in broken connections and half-downloaded files. Then the pitchforks would REALLY come out.

Re:This is an advertised feature I believe (0)

Anonymous Coward | more than 6 years ago | (#22474446)

Try downloading something from a server that has a good connection: []

Not every server has a huge pipe coming into it. Comcast can only provide so much

Powerboost (5, Informative)

SquierStrat (42516) | more than 6 years ago | (#22473736)

This is because of powerboost. As I understand it, powerboost makes the first 20MB download at a higher rate than your advertised bandwidth. Since bandwidth tests are done on such small files, you get a worthless result. The idea is that people who download lotsa of relatively small files get better performance, where as people downloading a lot of huge files like ISO images, full length movies, et cetera willg et initially good speed but after 20MB will feel like they are getting gipped.

Re:Powerboost (4, Insightful)

IndustrialComplex (975015) | more than 6 years ago | (#22473796)

I suppose it depends on how much it drops for those larger files. If it goes from 10Mbps to 1 Mbps I could see the point, but if it only drops to something lik 7 or 8 Mbps I think that's a reasonable rate. We also have to remember that this is a residential connection. It is designed for the typical residential user. That type of person will download a lot of smaller files regularly. The result is that the web browsing will seem very fast. ISO downloads? Not so much.

I wonder how it deals with P2P or a multi-streams of data. What if I have 10x 30Kbps streams running simultaneously would that aggregate and trigger the throttle down mechanism?

Re:Powerboost (5, Informative)

FritzTheCat1030 (758024) | more than 6 years ago | (#22473828)

I have Comcast's advertised 8 Mbps service and I very consistently get that downloading large files off of Usenet. I get about 25 Mbps for the first 20-30 seconds after I start a download.

Re:Powerboost (0)

Anonymous Coward | more than 6 years ago | (#22474310)

Same here. Im happy overall with the internet service. Not so much with the bundled overpriced TV service.

Re:Powerboost (1)

QuantumPion (805098) | more than 6 years ago | (#22474672)

Same here, although on my connection, late at night, I've gotten powerboost speeds for whole large file downloads. I downloaded one divx game trailer which was 600 mb in about 2.5 minutes! That's an average of 32 mbps! I really dislike Comcast's business practices, but I can't really complain about the service at my location.

Re:Powerboost (1)

morgan_greywolf (835522) | more than 6 years ago | (#22474010)

It's also important to understand that speed varies a lot by traffic, too. If you and thousands and thousands of other people are competing for bandwidth to download the latest Ubuntu ISO the day it comes out, say, in April, using the mirrors rather than a torrent, you're probably not going to get anything close to your 'advertised speed' -- and, in fact, in some cases you may be lucky to get anything at all.

And we know how Comcast deals with P2P data -- it inserts random RSTS to 'shape' their traffic using a man-in-the-middle DoS attack.

Re:Powerboost (2, Interesting)

kvezach (1199717) | more than 6 years ago | (#22473802)

Sounds like that could be tricked... instead of downloading a single ISO file, download 35 20MB files at boosted speed. Write a script to automate it, even. Or am I wrong here? If they disregard connections and turn off the boost after 20MB from when you first connected, then just downloading 21MB and disregarding the results for the first 20 should return the correct results for bandwidth tests.

Re:Powerboost (2, Informative)

petecarlson (457202) | more than 6 years ago | (#22473876)

Imagine it like a bucket with a fill rate of X and a drain rate of 10X. No matter how you work it, you are only going to get data over the long term at rate X although over the short term you could get speeds of 10X till your bucket is full.

Re:Powerboost (0)

Anonymous Coward | more than 6 years ago | (#22474650)

And that concept messes with QOS, well at least the limited QOS that I've messed with on MonoWall and my Linksys router with other firmware. If you set the max bandwidth in the QOS settings to your advertised normal bandwidth rate, you do not get the advantage of Comcasts "Speedboost". Setting your bandwidth to something higher to get some speedboost, the QOS gets jacked when the speedboost bucket runs dry.

Re:Powerboost (2, Insightful)

TheLink (130905) | more than 6 years ago | (#22473964)

Well if I did it, the boosts will be on a per customer IP basis. Not per connection. You would then have to be able to successfully _request_ for a new different and valid source IP address every few seconds, and then do the downloading. Good luck with that.

Comcast might do things differently.

Re:Powerboost (-1, Redundant)

Anonymous Coward | more than 6 years ago | (#22473960)

the first 10MB

Re:Powerboost (2, Informative)

QuietLagoon (813062) | more than 6 years ago | (#22474500)

While I was looking around for into on PowerBoost, I ran into these comments [] :

A Comcast official said the company is not boosting speeds for particular applications or content, a situation that would likely get Comcast into hot water with Net neutrality proponents, who want network operators to provide the same level of service to all content providers on the Net. Instead it's supercharging speeds for all customers downloading any content--whether it's music, e-mail, pictures or movies--when the network is not being used at maximum capacity.

"The Comcast network is really content-agnostic," said company spokeswoman Jeanne Russo. [/quote]

Re:Powerboost (0)

Anonymous Coward | more than 6 years ago | (#22474532)

They should advertise their anti-speed boost competitor option. I use a rival ISP and whenever I download legal torrents, half the time my DSL router not only gets forged rst packets, but also some sort of reboot command.

Re:Powerboost (0)

Anonymous Coward | more than 6 years ago | (#22474592)

feel like they are getting gipped.

People of Romani descent consider "gypped" to be a racist term.

Come on (1, Funny)

Anonymous Coward | more than 6 years ago | (#22473738)

Seriously now, is _anyone_ surprised over _anything_ bad Comcast does to their customers anymore?

HTTP (1)

hesiod (111176) | more than 6 years ago | (#22473744)

Most traffic is HTTP, being very small files. If it starts off very quickly, most web browsing would go extremely fast, while larger files would go at "normal speed"

Easy (2, Interesting)

RalphSleigh (899929) | more than 6 years ago | (#22473746)

Speed up web browsing for their customers while keeping those dirty bittorrent pirates at bay?

SpeedBoost (1)

Fenis-Wolf (239374) | more than 6 years ago | (#22473748)

What you're seeing is expected behavior. Comcast's SpeedBoost technology maxes out your connection for an arbitrary number of seconds at the begining of a transfer, and then reverts to a normal speed. If you watch their commercials advertising SpeedBoost closely you will see the disclaimer at the bottom of the screen.

Makes Web Browsing Seem Faster (1, Redundant)

dleewo (80434) | more than 6 years ago | (#22473752)

The majority of the downloads would be for web pages which are pretty small. I would think that's the reason they do this as it would make the web browsing experience seem faster.

Re:Makes Web Browsing Seem Faster (1)

brusk (135896) | more than 6 years ago | (#22473872)

It could also be good for streaming video/audio: get enough into the buffer to start playing in a couple of seconds, then keep streaming at a more leisurely (but still sufficient) rate.

Re:Makes Web Browsing Seem Faster (1)

sunking2 (521698) | more than 6 years ago | (#22474456)

For anything of length, this would actually be bad. You would quickly fill up your buffer, fooling the player into thinking it can sustain a rate that it can't. The result, 30 seconds into the movie you start clunking along. Reliable streaming depends on a constistent rate.

Compression (1)

sumi-manga (948999) | more than 6 years ago | (#22473754)

They use packet compression and your bandwidth tester reports seeing more data than it truly does.

Gasp! (3, Insightful)

Oxy the moron (770724) | more than 6 years ago | (#22473758)

Comcast? Dishonest? Say it ain't so!

All kidding aside, this wouldn't surprise me too much. Comcast (and probably all other providers) are advertising this super-mega-intarweb speed as "up to x mbps." So, theoretically, as long as *one* site can provide data at that rate, their marketing garbage still stands. Even if 99.9% of the other websites top out at 4kbps, if Speakeasy's speed test says it can transfer a file at 15mpbs, technically Comcast is correct. They are giving you "up to 15mbps."

Re:Gasp! (2, Interesting)

dal20402 (895630) | more than 6 years ago | (#22474462)

The usual Slashdot "assume dishonesty before checking out the facts" attitude...

Except that they only advertise 8Mbps sustained speed, which is what you get. They also advertise PowerBoost, which gets you ~25Mbps for a few seconds.

Comcast needs to be drawn and quartered over their forged packets, but they haven't done anything dishonest in advertising their speeds, at least not where I live. I do indeed get >20MBps for a few seconds and then 8MBps until the cows come home.

Re:Gasp! (1)

Oxy the moron (770724) | more than 6 years ago | (#22474696)

I assumed no dishonesty. I'm not a Comcast customer, and I don't pretend to know how good or bad their service is or know what range of services they offer. I have AT&T U-Verse, so I know that the "three fingers pointing back" rule applies if I were to make fun of them or call them liars/cheaters/etc. I simply pointed out that most people are unaware that they are buying "up to" whatever speed is advertised, and that they are not guaranteed to receive that speed at any point in time. In theory, if the scenario I outlined were in fact true, Comcast would not have over promised because there is at least one scenario where that download speed could be achieved.

But if Comcast (the company that forges/injects content into its subscribers packets without their knowledge) were to do that to hook a few extra customers, it shouldn't exactly qualify as a surprise.

PowerBoost (-1, Redundant)

tepples (727027) | more than 6 years ago | (#22473760)

Comcast has something called PowerBoost [] , which uncaps the modem for a few seconds when it detects that the user is uploading or downloading a large file. That might have something to do with it.

Wouldn't it help with browsing speeds? (4, Insightful)

Tranvisor (250175) | more than 6 years ago | (#22473764)

Most internet browsing is with relatively small amounts of data, so wouldn't front-loading of this nature noticeably increase browsing performance? Since this kind of performance is noticed by the majority of users it would seem to be something that increases their perception of their connections' speed.

I'm not saying that Comcast might not be cheating on purpose for speed tests, I just think that there might be another reason behind it other than just to make their test scores artifically high.

And it's old (1)

Ulrich_Skarsol (746706) | more than 6 years ago | (#22473768)

Comcast has been doing this for at least 8 months (thats how long they've been in my market) so it's not like this is something new...

Web browsing optimisation (5, Informative)

jackhererUK (992339) | more than 6 years ago | (#22473774)

Sounds like they have simply optimised their network to favour "bursty" usage, for example web browsing. This would seem a sensible thing for a consumer ISP to do.

Re:Web browsing optimisation (2, Insightful)

GodCandy (1132301) | more than 6 years ago | (#22473858)

I would have to agree. Most "normal" internet traffic is very bursty. You load the page then you sit there and look for a minute and then you load another. Sometimes you get the wild hair to download something large, at which point the provider limits your connection to prevent there network from becomming saturated. It is a resonable thing to do. I can't argue with it as long as the provider is stating that this is a few secconds at the beginning of a connection and will not sustain for the duration of your download of all 6 Star Wars DVD's.

Front-Load (1, Redundant)

Smidge204 (605297) | more than 6 years ago | (#22473780)

Is there any valid reason why Comcast would front-load transfers in this way

Your average webpage is not 100+MB. If they give you full bandwidth for, say, 2 seconds - most reasonable webpages will download completely within that time. It's not "cheating" exactly since they don't guarantee those speeds, but "up to" those speeds. They're not the only ones who do it, either.

Still a sleezy thing to do...

it's called PowerBoost (0, Redundant)

Anonymous Coward | more than 6 years ago | (#22473782)

Your bandwidth is increased for short periods of time. It's advertised all over the place.

This is most likely "PowerBoost" (2, Informative)

drcagn (715012) | more than 6 years ago | (#22473784) []

All it does is give you short bursts of high bandwidth and is really more talk than usefulness.

My ISP, Cox, does this too, though once the "PowerBoost" thing is off, I steadily get the bandwidth I'm supposed to get. Dunno about Comcast.

SpeedBoost is the thing (4, Informative)

eebra82 (907996) | more than 6 years ago | (#22473788)

Several months ago, New Englanders were the first consumers to experience Comcast Communications' latest high-speed Internet upgrade - PowerBoost Speed Enhancer. The speed upgrade is now being rolled out to Comcast customers nationwide. This new network technology temporarily doubles Internet speeds for consumers subscribing to the company's 6 megabits per second and 8 Mbps services, bringing download speeds to 12 Mbps and 16 Mbps, respectively.

Some consumers may not notice the speed increase when downloading smaller files, such as text-based e-mails and simple Web sites with few graphics. However, customers who frequently download large files, such as software, games, music, photos, and videos will now download at speeds that are faster than ever before. For example, PowerBoost significantly reduces the time it takes to download a one hour television program. Comcast subscribers at the 6 Mbps tier would reduce their wait time in half - from 4 minutes and 29 seconds to 2 minutes and 15 seconds. And MP3 fans will be able to download music files as fast as 2.2 seconds!
See more here []

Token Bucket (5, Informative)

Anonymous Coward | more than 6 years ago | (#22473798)

Um, this isn't a new concept, nor is it particularly sneaky: []

This is advertised (0, Redundant)

bconway (63464) | more than 6 years ago | (#22473800)

It's called PowerBoost [] . It's advertised on TV and radio every 5 minutes. They even have a FAQ about it. Google just might have a hint of it, too. Come on...

Re:This is advertised (0)

Anonymous Coward | more than 6 years ago | (#22474082)

You may be surprised to hear this, but 90% of those comcast ads you see on TV are overlaid on a network ad, so people who aren't on Comcast see something else. People who don't have Comcast will rarely see Comcast ads.

It gives priority to interactive tasks (1, Interesting)

Anonymous Coward | more than 6 years ago | (#22473812)

The total bandwidth for all ISP's is limited and people moving large files can dramatically affect the experience of interactive users. Give priority to the user who is clicking on a lot of small web pages and they will get better response. Non-interactive tasks like downloading don't need that kind of response.

There's only one... (0)

Anonymous Coward | more than 6 years ago | (#22473818)

There's only one kind of bandwidth test- uploading and downloading a large file. I don't know what else the author was doing, but it sure wasn't "bandwidth testing"- "burst-speed testing", maybe?

Advertised xfer speeds seem to be false, in general. This won't change until more people are aware and complain- (i.e., no time soon).

Its not cheating Its great feature.... (1)

jozmala (101511) | more than 6 years ago | (#22473826)

Think typical internet usage, its bursty. For more typical user case of relatively small files you get a nice boost in performance. If you download something bit then its another matter. The quick gives improves web surfer latency without taking much of the bandwith. They have limited bandwith and they probably cannot give that kind of speed up all the time.

Nothing wrong with PowerBoost (1)

EmagGeek (574360) | more than 6 years ago | (#22473854)

Oh come on people. Can you please just stop the witch hunt? Comcast advertises this as a feature, and to me it's actually pretty convenient. I can imagine that most downloads are probably less than 10MB in a single burst, so giving the user the first 5 seconds or so of transfer at a higher rate helps the consumer see a faster internet. Keeping sustained transfers at the advertised cap speed ensures one user can't gobble up all the bandwidth over a prolonged period of time. Everybody wins.

This is not too different than how metered T/OC-x connections are operated. These metered T/OC-x connections bill you based on your sustained bandwidth, so yeah, you can have short bursts without getting a gigantic bill, but if you are pegged at 50% all the time, your bill will be huge.


Re:Nothing wrong with PowerBoost (1)

ampsonic (788883) | more than 6 years ago | (#22473932)

As long as comcast is upfront about how this technology works (which may be unlikely), it seems to be a useful feature. If most users see improved speeds over most of their internet use (ie: webpages, emails) it doesn't seem like a problem.

Are they adveritising there service at the powerboost speed or at the speed it drops to?

Re:Nothing wrong with PowerBoost (1)

EmagGeek (574360) | more than 6 years ago | (#22473974) []

This explains everything about PowerBoost. In short, they do not advertise the maximum speed at which the connection will operate during the burst. They explain clearly that your connection will run at your provisioned speed after the burst is over.

Tin foil bushes. (1, Insightful)

Anonymous Coward | more than 6 years ago | (#22473860)

"Is there any valid reason why Comcast would front-load transfers in this way, or is it merely an effort to prevent end-users from being able to assess their bandwidth accurately?"

The thing I'd like to know is how you all make it through the day seeing conspiracies and evil doers behind every bush? I'd think you'd burnout.

Re:Tin foil bushes. (2, Insightful)

Dimitrii (958525) | more than 6 years ago | (#22474440)

I'd think you'd burnout.
I've worked with quite a few conspiracists and finding a new one seems to invigorate them. It is a positive feedback loop that can be quite entertaining if you don't get as invested in making them see the truth as they are for you.

may be there is no malice here? (1, Interesting)

Anonymous Coward | more than 6 years ago | (#22473868)

If what you say is true, there is a possibility comcast is doing it with good intentions. In mainframes, we have a concept of "period performance objective", the main idea being transactions which complete in short intervals get priority over transactions that take longer. Every transaction (in a group) will start with same priority, if it doesnt complete by a predefined period, its priority gets lowered a notch. if the transactions didnt complete in the next period too, the priority gets lowered even further. the period length, number of periods, and the quantum of reductions are all customizable. This is usually defined for online users. so a user executing a transaction that takes 0.1sec will keep getting faster response, whereas a user executing a 10sec transactions will get sluggish response. so, comcast may be doing the same. it is protecting ordinary browse or chat or email from heavy downloaders.

Not cheating (0)

Anonymous Coward | more than 6 years ago | (#22473906)

This behavior from ISPs is not uncommon and not a trick: []
Comcast may do many fishy things, but this is not one of them. As far as I know, the steady-state rates are as advertised and the burst rate is just an added bonus.

Seems normal (1)

pembo13 (770295) | more than 6 years ago | (#22473934)

I've come to the conclusion that those Speakeasy tests are way too optimistic on my RoadRunner connection as well. Need to find a more reliable way of testing. I wouldn't be surprised if ISPs just simply boost connections to Speakeasy as well -- would at least explain how when browsing all other sites is slow, and then doing the Speakesy test I get a high score.

The only way to determine speeds (1)

nlitement (1098451) | more than 6 years ago | (#22473936)

The only way to determine speeds is by torrent because any amount of latency will reduce bandwidth over TCP, so to compensate for that we need to connect to as many fast clients as possible, that are as close as possible to you. I've gotten 24150kbps down and 2050kbps up on torrent.

Oh, but we're talking about the American ISP Comcast.. that throttles everything.

Comcast this, Comcast that... (0)

Guppy06 (410832) | more than 6 years ago | (#22473944)

What, has Comcast become the new SCO or Sony around here?

Speeds (2, Informative)

Sunar (1100779) | more than 6 years ago | (#22473976)

If you are only getting 1.2Mb sustained on Comcast you have a problem. I can pull 6Mb steady for hours on end using Comcast. Like others have said though...Speed Boost will make tests show different numbers at times.


If those clients are running Windows... (3, Informative)

thejynxed (831517) | more than 6 years ago | (#22473978)

You just might want to check that their connections are properly tweaked as far as RWIN, MTU, etc go. 14/5 compared to 1.2/290 is a vast, vast difference that should never happen if they are paying for a certain tier of service, even if it is advertised as "up to" that higher rate. I'd also do a smoke ping and line quality tests, etc over at BroadbandReports, because there is something definitely not right with those connections if that is the average drop in performance. There may also be mis-configured firewalls, routers, mis-provisioned lines, water leaks, etc causing such issues.

My advertised and provisioned rate via Atlantic Broadband cable is 5/512. I am actually getting closer to 6 or 7 down and 468 up at all times due to some tweaking I did. Even the AtlanticBB tech seemed a bit shocked that I was getting more than 5 down, and said it was unusual, but they wouldn't re-provision the line or anything because of it. I count myself lucky, because Verizon's service here is absolute rubbish - $25.00/month for 1.5/768 DSL that, shall I say in the politest way possible, isn't actually working for more than two weeks per month because they are too cheap to replace lines that were put up in this town sometime in the 1950's at the latest (Not to mention they never actually bother to show up for scheduled appointments to rewire buildings that were constructed pre-1900, such as mine - big old Victorian type home turned into apartments).

Powerboost does mess with speed testing, however those "tests" are very rarely accurate anyhow, as I can rate higher on a test to Seattle or Los Angeles than I do to say Pittsburgh, Toronto or NYC, which are MUCH closer to where I live (by several thousand wire miles). It's more accurate to calculate your average rates by downloading/uploading large files from/to a university/public FTP or something, at least in my experience.

Speakeasy / (1)

shamer (897211) | more than 6 years ago | (#22473990)

I was assuming they where in bed together, Comcast and the 2 top bandwidth speed testers that is. Though Speed boost makes just as much sense.

Weather this is true or not, it's just a revisit to an older /. post []

Re:Speakeasy / (0)

Anonymous Coward | more than 6 years ago | (#22474326)

Do you mean "whether"?

Weather is like rain, or snow...

Charter does it too.. (1)

keepr (613447) | more than 6 years ago | (#22473996)

Charter does this too.. It's standard practice lately for cable providers. It makes them look better and it helps out the end user by allowing them to "burst" small amounts of data (like websites). This is a function of traffic shaping, I dont see any harm in it. Just test your connection speed with real world application instead of these speedtest sites. You will get a lot better picture of how fast and "stable" your clients connection is if you download a 100mb file from an ftp site and then put it back up there. You will be able to see how much jitter they have in their connection and work out an average speed.

Note to ISPs (1)

Bender Unit 22 (216955) | more than 6 years ago | (#22474020)

Internet connections are not just for websurfing and emails anymore.

Of course it depens on the user, the average traffic from my xbox 360 alone (in gaming, demo downloads, movies etc) in one day, is more than my parents have in a month with their just light surfing and email use. And I don't use my xbox that much.

It is an issue they have to face now. Legal traffic alone these days for high tech households internet use, can pass your ISPs secret acceptable use limits.

No Powerboost for Me (1)

jfade (1096961) | more than 6 years ago | (#22474038)

None of the Comcast Lies and Propaganda about this so called "Powerboost" are true for me at all. In fact, last time I ran a speed test I only got 384 kbps up and something like 4-6 mbps down. Hardly an "improvement". In case you were wondering, no, I wasn't running any torrents at the time. In fact, I didn't have anything else going at the time so I have no idea why it was so slow.

Just develope a system (1, Insightful)

LM741N (258038) | more than 6 years ago | (#22474046)

that takes advantage of this by downloading in an on/off switch manner.

Re:Just develope a system (1)

prxp (1023979) | more than 6 years ago | (#22474540)

just develop a system that takes advantage of this
you mean like a distributed peer to peer network of users that would serve tiny parts of a larger file to each other, thus making the download session for each of this part fit the speed bust grace period and as a consequence would make the entire large file be downloaded with the increased bust speed? That's just Genius!

QoS limits (2, Informative)

Sniper98G (1078397) | more than 6 years ago | (#22474062)

This is a result of "burst rate" which is an asignable property in QoS. The idea is to allow small files like web pages to load much quicker then large file transfers. Most ISP's are doing this now as a means to speed up web browsing. The best way to get an acurate speed mesurment for file transfers is to download a large file while using bandwidth monitoring software.

It's Powerboost apparently (-1, Redundant)

Anonymous Coward | more than 6 years ago | (#22474086)

I'm surprised no one's mentioned it yet...

How about an answer? (4, Informative)

WhyMeWorry (982235) | more than 6 years ago | (#22474114)

I know that this is slashdot but I'll try to answer some of the OP's question anyway. Of course I won't do any original research myself, but rather rely on information from the previous posters or make things up as I go.

Q1. Is there any valid reason why Comcast would front-load transfers in this way?

Yes. Most requests from browsers are for short files. By upping the speed for short requests, pages will render faster. This is a plus for the user, as he spends less time idling. Long downloads on the other time are expected to take a while to complete; the user expects to be able to walk away from the computer for a while. Thus Comcast can argue that they have greatly enhanced the experience of the web browser by stealing a few cycles from the downloader. I would welcome such a plan as long as the ISO downloading speed is reasonable.

Q2. Is it merely an effort to prevent end-users from being able to assess their bandwidth accurately?

It would have that effect on a poorly designed bandwidth test. Bandwidth testers try to make the download size long enough to counteract tcp connection costs and to average over variations in download speed. Comcast has just given them another variable to take in to account. Interestingly, there are some test suites that are designed to detect what Comcast is doing and give them extra credit for it. They bill their tests as real world throughput tests. They want to indicate what the effective bandwidth is while browsing web pages that reference many images or javascript files.

Q3. Is Comcast cheating?

If Comcast is just doing this when accessing known test sites then they are cheating. If this is their policy for all connections then the worst that can be said is that they are optimizing their service to a particular class of users (surfers as opposed to downloaders). If you are in this category, then you should be happy.

Frontloading (1)

Galen Wolffit (188146) | more than 6 years ago | (#22474134)

My made-up statistics show that the vast majority of users are downloading relatively small files. When you hit a web page, the browser downloads many small files. When you download anything via a P2P protocol, you're once again downloading very small files (that is, each peer sends you a small chunk of the file). Boosting bandwidth for the first few seconds of a connection can significantly improve the user experience without placing a constant drain on the network.

Unless they advertise it, it's fraud, but it makes sense.

I wish (1)

smartin (942) | more than 6 years ago | (#22474154)

I wish that Verizon did not block ports 25 and 80. I already have FIOSTV and would switch to their internet service in a heartbeat but I don't want to give up my web and mail servers.

Re:I wish (2, Informative)

Ioldanach (88584) | more than 6 years ago | (#22474404)

I wish that Verizon did not block ports 25 and 80. I already have FIOSTV and would switch to their internet service in a heartbeat but I don't want to give up my web and mail servers.
They'd be happy to unblock those for you, and give you a static ip, for $99.99 per month [] with a 2 year agreement.

See link here (2, Informative)

MECC (8478) | more than 6 years ago | (#22474180)

Comcast has been doing this for a while [] now.

Typical for shared bandwidth solutions (0)

Anonymous Coward | more than 6 years ago | (#22474194)

This kind of prioritizing of the first X bytes of a connection or X seconds of traffic over a period of time is a typical way of boosting the user experience on networks which share the last mile bottleneck between clients. Advantages are similar to IP-header based traffic shaping, but without the user-end hassle or complex and changing priority tables.

If a speed test is not suitable to measure this and the ISP company delivers what has been advertised, it's up to you get it right.

Iperf (3, Informative)

MT628496 (959515) | more than 6 years ago | (#22474280)

Iperf [] , or something like it is what you should be using for speed tests. Set up the daemon on a machine that you know you need to access and tell it to send a ton of data a few times. See what the results are. Those speed tests test how quickly you can communicate with some random server that you'll never need to send any presentations or video files to in day to day business.

Remove this story or comment at the bottom. (0, Redundant)

WindowLicker916 (704800) | more than 6 years ago | (#22474318)

As EVERYONE has pointed out, this is an advertised feature so Comcast is not "cheating". Instead of people automatically assuming to Comcast bash I think it only proper of the Moderators to post at the end of the story that this article is inaccurate and is part of a service feature. Most people don't bother reading comments, so Slashdot is feeding false information. I read one users post...I can't believe their cable company makes them pay for powerboost when Comcast offers it free!

It's true (4, Informative)

soren100 (63191) | more than 6 years ago | (#22474422)

I can assure that they do absolutely do this, and it is really annoying.

It's really bad on uploads -- I just ran a test and I got 300 KB/s for the first 5 megs, then it degrades 100 KB/second over the next few megs, so that by the time you have uploaded 14 megs you are getting close to 40 KB/S in upload speed, and the connection is so bad that the shared digital phone line does not have enough bandwidth to have a phone conversation. Stop the upload and start it up again, and you get 330 kb/second, with the same degradation curve.

For downloads they do the same thing, but not so severely -- I downloaded a 67 meg file and it ran at about 750 KB initially, but then dropped to around 350-400 KB/S (according to the FTP app) about halfway through.

So for anyone using the connection for smaller file sizes (like the speed tests) you seem to get "blazing" speeds -- I ran the test at a couple of the internet speed test sites and they both think that I have 12000-14000 kb/s download speed and 2700 kb/s upload speed.

So if I didn't have any other way to measure it, I would think that I was getting way more than I paid for, rather than something that in reality is very pitiful.

Speedburst in networking (1)

wyztix (1078477) | more than 6 years ago | (#22474464)

I didn't read lots of replies so it may already been stated. What comcast is doing is simple network engeneering. Using a "burst" architeture allow to quickly send small files, at the detriments of long one. Why doing so? simple QoS. It's an easy way to create some degre of QoS without having to introduce more complex technologies. Just think about what are "small" vs "long" files: Small: multimedia using UDP (VoIP,streaming), Web Pages, text emails, instant messenger, most games. In fact mostly what people use their connection for. Long: Email attachments, file downloads, "torrents" Most people can wait for their downloads 2-3 minutes more, but you just can NOT wait a second for a multimedia paquet to arrive. So by doing a "burst" strategy, they give "priority" on small files which doesn't congest your network for long, while slowing the long files that congest everything for quite a time. It's about the same as cars vs buses. By giving more speed/priority to the cars vs the buses, you allow more vehicule to use your road over time. Even if the amount of data transmitted is lower, the amount of different data is higher.

The LIES and DAMN LIES they are... (0)

Anonymous Coward | more than 6 years ago | (#22474684)

I was poking through my network,
and I am on comcast, and a lot of funny things happend.
If was using TCP/IP for a traceRT, I was getting one route,
and if I was using regular old UDP, I was getting another.
Bandwidth tests are those same flakey numbers,
Start fast and then crawl

Looks like they are splitting ports at the heads, and
routing diffrent port traffic and profiles in diffrent directions.
If you try chasing routs for either or p2p,
you get the frealing run around, but at least,
after a while requests get rerounted to a faster net.
but the P2p stuff always stays on rediculus routing tables.
Theough 4 or 5 local, 6 or 7 regional...3 or 4 optical gateways before it leave comcasts net for good.

I recently switched to openDNS, and noticed that, the DNS was a first slow, then was fast, and now its the DNS is always fast. They are really profiling everything, and optimizing everything. I want to get something like a multi-port EtherAPE and just profile the sh*t out if all the ports, and see how they respond through time.

F*CK comcast, and the horse they rode in on. I would, as a business optimize for what ever the customer wants, they want to optimize for what ever would 'appear' to be fast, and screw all the rest. People are reporting problems with VIOP on comcast too!

No they aren't cheating. (1)

wolferz (1173471) | more than 6 years ago | (#22474718)

Comcast began providing this feature where I live almost a year ago. Cable providers have always capped their clients. Each cable node often can provide 60 megabits at a time easily, though most end servers don't allow a sustained download at that speed. However If clients are left completely uncapped a hand full of users could possibly soak up all the available bandwidth. If you have even gotten stuck on a 10mbps network with some one who likes to play games or use p2p software you will have seen this in action. For that reason users are given a set limit on their individual downloads and uploads. About a year ago here Comcast began uncapping users for the first 30 seconds of any connection. The concept is that web browsing and streaming media will benefit from the burst of speed (up to 25 mbit in my area) while services that would be capped on the servers end any way (file transfers) will be mostly as they always have been. A best of both world scenario. With the increasing use of active media in web pages it makes sense that short lived connections that wouldn't really take away bandwidth from any one else should be allowed to download as quickly as possible. They aren't the only cable provider that has started doing this ether. Time Warner just told a friend of mine when he moved into a new apartment that they were offering the same thing.

Ummmm, Learn More (0)

nuintari (47926) | more than 6 years ago | (#22474768)

Of course, clients get nowhere near this performance in everyday usage.

Of course not, high bandwidth does not mean that every connection you make will be fast, it is more about capacity. The fastest download you will get from any given host on the internet is determined by the slowest link between those two points. If you have a 10 mbit connection, but the file you want sits on a server behind a T1 line, you will receive that file at a maximum of 1.5 mbit, probably less, as congestion has to come into account as well.

(This can be quite annoying when trying to determine whether a client needs to switch over to a T1 or if their current ISP will suffice.)

1) You do realize that a T1 is a fairly slow connection by modern standards right? It caps out at a flat 1.5 mbit down/up, no burst (which I will come to in a second) If they are getting _anything_ over 1.5 mbit down, it is not in their interests to switch.

2) you have heard of MRTG right, graph their asctual usage, see what they actually use/need.

Upon further investigation, it appears that Comcast is delivering this bandwidth only for a few seconds after any new request and it is immediately throttled down.

This is not some dark hidden secret of Comcast, this is called burstable bandwidth. Almost all last mile technology supports this, and most networks use it. It is great for sending that message with the big attachment, or downloading a decent sized file.

Is there any valid reason why Comcast would front-load transfers in this way, or is it merely an effort to prevent end-users from being able to assess their bandwidth accurately?

God you are paranoid. Burstable bandwidth also has the happy side effect of making sure that no one connection will saturate the link. Connections that take too long are slowed down, freeing up bandwidth on the customer's circuit so they still have nice and fast browsing. This is about improving the quality of service, you have put such a spin on it in your own head, you just cannot see it.

Does anybody know of other ISPs using similar practices?

Yes, mine, your precious speakeasy, time warner, verizon, sprint, earthlink, mom and pop ISP 1, mom and pop ISP 2, mom and pop ISP N. We all do this! It says very clearly in most ISP contracts what your actual service is is rated at. So much down sustained bandwidth, so much burstable for X number of seconds.
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