Comcast Cheating On Bandwidth Testing?

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?"

Comments

Wouldn't it help with browsing speeds?

[Tranvisor]

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.

Re:Powerboost

[IndustrialComplex]

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:This is an advertised feature I believe

[jandrese]

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

[arivanov]

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.