[e2e] Skype and congestion collapse.

[David P. Reed]

The "512 kb limit" upstream on cable plants seems a bit bogus to me, as 
I just ran a test and got sustained 741 kb/s upstream to Los Angeles.

A small correction about cable modem nets (Ran knows a fair bit so he 
may correct me).   Cable modems sit on networks with an architecture 
called HFC, Hybrid Fiber Coax, which is designed so the number of homes 
passed is dependent on where in the cable distribution tree the plant 
turns from fiber to coax.  In advanced operators (Comcast and RCN out 
here) the fiber goes out very close to the users, and has moved closer 
as the upstream demand has increased.   I happen to have a fair amount 
of contact with Comcast execs, and their plan is to move fiber even 
closer to the users, reducing the number of homes per coax segment.   In 
recent conversations with CableLabs execs (my namesake, David P. Reed, 
and Richard Green) regarding the DOCSIS capabilities indicate that they 
are quite aware of the need for more upstream bandwidth, because they 
see the asymmetry going down as more and more bittorrent, etc. is 
deployed.   So while YMMV depending on how sluggish your operator is, 
HFC is generally pursuing a strategic direction to go well beyond the 
current upstream limits.   Thus, the upstream link share level seems 
likely to go down.

Ran may have other data that contradicts this, and I have to admit today 
I've *only* got 784 Kb/s upstream and 7 Mb/s downstream on RCN, so it 
might be a year or so before I get past a megabit upstream for my $50 
per month.  [happening to live in a place where RCN and Comcast compete 
head-to-head has strong benefits... especially since Verizon DSL has so 
far refused to be competitive anywhere in Massachusetts].