Call Comcast and have them run a line test from their end. This will
have them also check for too much attenuation (causing lots of retries)
or too much signal (causes problems, too, maybe echoes). The other test
you can do at your end is to check if you have lots of packets getting
lost. Comcast's web site is pingable so run:
ping -n 100
www.comcast.net
When you ping just 4 to 10 times, the connection might look good without
much or no loss. But pinging many times will give a better picture of
how much loss you actually do incur. If there is too many lost packets,
all the retries will slow down file transfers and make e-mail flaky,
too.
Comcast's policies make no guarantee of a minimal service level (i.e., a
minimum speed). They make all sort of claims in their advertising and
back NONE of it in their policies. The best I could wrangle out of
Comcast is that they will try to keep broadband speed (downstream only)
above 256 Kb. With ISDN, you got a minimum service level. With
broadband, you get whatever they feel like giving you and it seems they
do little to monitor their segments to guarantee an average minimum
service level. When my cable broadband provider was local (MediaOne),
they were very well informed and did guarantee a minimum service level.
Then AT&T bought them and the guarantee went away but AT&T still make a
statement as to what you should expect and if you got lower then you
could contact them about too much flooding on your segment. Comcast
doesn't give a damn and just wants your money. I'm stuck with Comcast
because they are the only broadband provider in my area, but I keep
watching to see who else might offer it (although all of them would
simply be contracting with AT&T to provide the actual service in my
area).
