Some truth about Comcast - WikiLeaks style

Lamar Owen lowen at pari.edu
Tue Dec 21 13:08:52 UTC 2010


On Monday, December 20, 2010 06:36:03 pm you wrote:
> Those are all still sub-T1 on the uplink and well below normal CMTS service
> speeds. Low-end CMTS is around 15Mbps/7Mbps.

Yeah, at least with the T-1 you aren't oversubscribed.  One company for whom I consult was going to go from their T-1 to an 11/1 DSL, but they do streaming audio and video, and I was able to talk them out of it.  I've been asking the provider to sell that place a matched pair; give me an 11/1 DSL, and then give me a 1/11 reverse ADSL on a different pair, and I'd be a happy camper.

> The AT&T cable plant in my neighborhood is unable to
> sustain any better than 1.5mbps/384k on ADSL.
 
> > Their copper in my area is nearly new, they have spent the last five years or so refreshing and updating their copper outside plant.  
 
> That helps a lot. It still doesn't compete with CMTS which was my point.

Interestingly enough, we've tried to do H.323 with some folks on a CMTS connection, and have yet to succeed in smooth video.  My testing on my home DSL, back when it was 1.5M/.5M (we got two free upgrades; the first one was to 5/.5 and the second to 7/.5) and our main link was an OC3 to a different provider, went well.  Never really figured out what it was causing the problems with the CMTS users; the effect was that the H.323 session would start up and negotiate at 384Kb/s, and a few seconds of video would traverse fine, and then the link would start dropping more and more frames until it died entirely; my testing on my slower DSL didn't have this problem, and traceroute showed an equivalent number of hops between.  The CMTS connection in use was an 8M down 1M up link.

And I don't have cable available to me at all.  So it's DSL or nothing at home; even Verizon's 3G, which works fairly well at work, doesn't work at all at home, 1,200 feet away (terrain issues).  And I don't have visibility to the most common data satellites on the Clarke Belt. 




More information about the NANOG mailing list