Comcast and Net Speed Tests

JimDaGeek writes "I recently moved to Columbia, SC where I have Time Warner as my cable ISP and pay for an 8 Mbps connection and have been very happy with the service, speed, and reliability. In contrast I have heard bad things about Comcast. So now that I am up in the Philadelphia PA area visiting my parents, I decided to test out the speed and reliability using the Speakeasy speed test. The results surprised me. Here are the reported download speeds in Kbps: New York, 18,946; Washington, 15,821; Atlanta, 11,257; Chicago, 10,042; San Francisco, 4,230. What is going on? I know my father is not paying for a 10+ Mbps connection. Is Comcast giving priority to popular speed-test sites?" From Comcast's site, in the Philadelphia area they seem to offer download speeds of 6 or 8 Mbps, with an option for a "PowerBoost" to 12 Mbps on large files. This wouldn't explain the results JimDaGeek got of almost 19 Mbps down.

Update: 07/10 12:07 GMT by KD : A friend in Massachusetts had a tree fall on his house. The Comcast guy who reconnected the lines told him that they are boosting the line speed to 20 Mbps down / 2 Mbps up in certain areas to be more competitive with Verizon FiOS.

Comments

SpeedTest.net

[ragnarok]

The Speakeasy speed test is just a re-branded version of speedtest.net. They have a lot more test locations to choose from there.

Re:SpeedTest.net

[Lumpy]

and it's a worthless test.

One big transfer != bandwidth capabilities.

Give me 100-500 smaller files with smaller ACK going back. that gives you a real test that will show latency and jitter.

also check many different ports. Port 80 get's priority. Ports above 8000 get lower priority. Ports for Voip are screwed with hard.

Re:SpeedTest.net

[Anonymous Coward]

bandwidth != latency. You want both (high bandwidth and low latency, that is), but that doesn't make them equal.

Time of day?

[carlivar]

Since cable bandwidth is shared, wouldn't the time of the test matter? I've noted (very unscientifically) that my Internet seems slower between roughly 7-9pm (on Charter in Los Angeles area).

Re:Time of day?

[catwh0re]

It also makes me think of how complicated the simple "bandwidth test" will be should net neutrality get thrown out the window.

Already we juggle the factors of location, "paid for speed", shared bandwidth issues with daytime or peak traffic.. but then without some kind of neutrality we'd also be juggling whether or not the interconnects between yourself and the test site are all on a higher priority or lower priority pipe.(something we could never know)

Today your ISP can blame a bit of the slowdowns on network conditions, but ultimately it's obvious if your ISP is a slower provider.. but in the future they'll be able to knowingly serve you slow speeds while claiming it's just the low-priority sites you may be visiting.

Re:Time of day?

[MrShaggy]

Since cable bandwidth is shared, wouldn't the time of the test matter? I've noted (very unscientifically) that my Internet seems slower between roughly 7-9pm (on Charter in Los Angeles area). I look at the difference between cable and dsl as 2 different ways of getting to a train-station.


Cable might be like taking a bus to the station. There might be other people there. However, its not that significant.


Dsl is like taking your car or a cab to the station. It definitely is not a shared ride into the station.


The one thing that happens is that everyone gets off of there rides, and they all take the train out. Pretty much at the same speed.

Of course during that time of the day there are many people on the internet, so it won't matter what you are using. Its somewhat insignificant how 'slow' it is. The only thing that kills the dsl is how far away you are from the office. Thats pretty wild. The thing is that you can get speed tests from eith side of the country or even planet. So even if it isnt the rush hour here, it will be elsewhere.


Thats why I think most dsl ads are so misleading.

Re:Time of day?

[Matey-O]

Oh, what I wouldn't do for a personal T3...

What, short of paying money for it?

Re:Time of day?

[ivan256]

Yes, and your cable connection uses a shared upstream connection once it reaches the CO too. The difference is that the "last-mile" connection is also shared. Either can become a bottleneck depending on traffic.

Of course the internet traverses shared lines. That's practically the point of the internet.

Re:Time of day?

[CopaceticOpus]

What, short of paying money for it?

Dude, a T3 would be almost as expensive as just buying all those CDs and movies.

:)

PowerBoost

[the_cowgod]

The Speakeasy test regularly reports over 20Mbps on my Comcast connection. The "PowerBoost" feature allows basically uncapped speeds for the first ~15MB of a transfer, then it drops down to the normal 6Mbps. I can easily see this effect when doing large downloads with my UsenetServer account. It does inflate speed test results, but Comcast does not appear to be favoring the test sites in any way.

Download a linux distro

[Raleel]

Someone above mentioned using jigdo to get all of debian, but even using wget to get a full dvd or cd set of some distro will provide you with a good data point. That's been my standard test for quite a few years now.

20 Meg Cable Modems Practical Since 1999.

[Dave Burstein]

19 megabits on an unloaded cable modem node is quite practical, especially for brief speed tests.The U.S. cable modem architecture is based around nodes that share 35 megabits or so downstream. RCN even sells a 20 megabit service, which David Reed buys and reports gives him the promised 20 megabits most of the time. In practice, most nodes run with 5-10 megabits typical load, as only a fraction of the time multiple users on one node simultaneously download megabits and fill the pipe. Statistical multiplexing (sharing) works much better than people expect on cable modem networks, especially on well managed nets that split nodes and otherwise expand capacity when needed because a node gets frequently congested.

Comcast and cable suppliers are working on several techniques to allow customers to get more than the 6 or 8 meg typically allocated, while not causing undue congestion. "Speed burst" technology tests the network load, and if uncongested temporarily raises the speed of an individual modem making a fast download for a brief period. While that's marketed as "doubling" speeds to 12 and 16 megabits, bursts to 20 and 25 megabits are also practical.

The new technologies require upgraded equipment and are typically being tested first and then rolled out market by market. So it would be no surprise if a subscriber in Philadelphia (Comcast's home town) is benefiting from a test or early deployment of faster speeds than Comcast customers elsewhere.

100 megabit+ (shared) cable modems are being deployed in Japan, Quebec, and France, bonding 3 or 4 35 megabit channels for higher speeds. These are early "DOCSIS 3.0" products, unlikely to be widely deployed in the U.S. until 2009. Comcast's CEO, Brian Roberts, demonstrated 100 megabits at the cable show in Las Vegas this spring, and will probably test widely in 2008 and go into deployment (especially where Verizon is building FIOS) the following year. DOCSIS 3.0 requires a new cable modem unit, however, so this customer is unlikely to be an early tester.

That doesn't explain why the test to San Francisco only ran at 4 megabits, which could be explained by node congestion a few minutes later, inferior Comcast backbone connections to Speakeasy's host in San Francisco, or other circumstances. For more details on coming faster cable modems, google DOCSIS 3.0.

Dave Burstein

Editor, DSL Prime

REAL BANDWITH TEST

[logik3x]

http://miranda.ctd.anl.gov:7123/ Can't stand seeing people using speedtest.net, MOD THIS UP!