Diffserv service classes

Sun Nov 21 19:54:16 UTC 2004

Hi,

#There are certainly applications and users out there that would
#like to use all of the bandwidth possible, but do not need
#to step on other, more bit sensitive, services.

They might want to, but unfortunately we (the Internet2 community
as a whole) have had limited success in helping them routinely achieve
higher throughput for bulk transfers. 

Again refering to http://netflow.internet2.edu/weekly/20041108/ see Table 1:

-- The median throughput for bulk TCP flows is still less than 3Mbps.

-- The 95th percentile for bulk TCP flows is still less than 15Mbps. 

There is an I2 end-to-end performance initiative designed to improve those
numbers, but at root, because most of the PCs that scientists and
students work from are not shipped from the vendor pre-tuned for high 
throughput, average throughput numbers remain low. When PC vendors begin 
to read http://www.psc.edu/networking/perf_tune.html or http://www.web100.org
and offer higher education special SKU's preloaded with OS's tweaked per 
those approaches, then, maybe, we'll see average performance routinely 
increase and congestion become a pragmatic issue.

Until then, it will be routine to see most Abilene connectors run at 
only a fraction of their potential capacity, e.g., see:
http://stryper.uits.iu.edu/abilene/aggregate/html/report-2004-11-20.html

Shrug.

Regards,

Joe