<OT> How do ISPs work?

[Tony Alfrey]

Not necessarily linux specific.  But I thought someone might know.

Setup:  Using both SeaMonkey and Firefox on intel Mac.  Using Firefox on 
SuSE.  ISP from home is Comcast cable.

Problem:  Recently, SeaMonkey has slowed to a crawl in accessing a first 
webpage after start-up (three minutes to render the first page). 
Successive pages render OK but not super fast.  Firefox has no such 
problem.  Unfortunately, only Firefox on the SuSE box so can't compare 
apples and oranges.  Now today, magically, the problem disappears.  And 
also, I cannot recall this problem from various free wireless hot spots.

Why do I care?
Because a guy on the SuSE list who uses SeaMonkey for his mail client, 
and Comcast as his smtp server, claims that Comcast has been "blocking" 
the use of SeaMonkey and telling everyone they should be using Outlook 
or Internet Exploder.  Also, one hears rumors that Comcast is somehow 
slowing access to bandwidth hogs, implying that they keep records of 
usage from particular IP addresses.

Question:  Is this actually possible, i.e. that an ISP could give 
selective web access to a particular web browser?  Does a web browser 
somehow encode within its packets some identification?

-- 
Tony Alfrey
tonyalfrey at earthlink.net
"I'd Rather Be Sailing"