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.

DOCSIS 2.0 Plus

[Fallen Kell]

It all depends on the cable modem that you have. Some of the new motorola modems, like the SB5120, do not have the ability for Comcast to limit as much as they sometimes like. Comcast themselves has not been too worried about it as long as the network segment you are a member of is not over-crowded. They see it more like a new benefit which allows better competition against FIOS. Personally I average 25-28mbps on my modem.

Here is a current snapshot:

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.

Lots of factors...

[SuperBanana]

To name a few:

• Router/signal compatibility. Comcast has switched signals several times and in two cases, it caused horrendous performance. There's also a particular cablemodem (has a big blue "sleep" button on top) that has serious problems with high packet rates and connections (ie, BitTorrent crashes it.)
• Interference.
• Local loop, backbone, and uplink utilization. Guess what, guys? Sometimes traffic peaks for strange reasons. Sometimes it's a virus outbreak, a new movie trailer, or a big news story.
• THE INTERNET . It's unreliable, not guaranteed, never has been, and YOU ALL KNOW THIS AND HAVE BEEN TOLD IT OVER AND OVER AND OVER. I work for a university. We have seriously fat pipes. We have a 10Gbit backbone. And some sites I can FTP from at 2MB/sec. Others, I get 40KB/sec. "Speed tester" services compete for bandwidth just like everyone else. Stop holding them up as some pure, holy source of internet traffic that magically flows through every router at maximum speed.
• Some content is akamai-zed. I get Apple's software updates at maximum line speed, for example.

If you're not happy with your service, CALL THEM. My parents were some of the first people to get MediaOne service back around '98-'99, and every time they had problems, we picked up the phone, and it was taken care of.

I've had the same experience elsewhere. Any time I have problem with the service, be it regular disconnects or lousy performance- I pick up the phone, and a few minutes later someone is checking into signal to noise ratios and such. If you lease the modem, they're usually happy to try sending out a tech and swapping out a modem if you're polite but clear there's a problem. They're usually even more amenable if you pick up the modem yourself at a "service center."

In my years as a customer and having friends who were customers, I've seen a)flooded junction boxes b)in-house distribution amps turned up too high c)1 failed modem d)one buggy model e)several incompatible modems after "upgrades" to the area network (usually to support faster speeds.)

In short: call comcast, ask them to look into it. They've almost always been helpful, through all the various company changes: MediaOne, RoadRunner, etc.

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!