The "secret" performance penalty of third party ISP's

Stefan Savage (savage@cs.washington.edu)
Fri, 30 Apr 1999 09:26:46 -0700

While surfing some academic sites I noticed that I was getting lousy service
from home. Checking the same route from school the path quality was much
better. I was surprised to find the bottleneck in sprintlink since they are
generally our preferred provider. It turns out however, that UW routed via
the vBNS. In retrospect this is obvious, but I hadn't considered this
before as a general issue.

Basically, a big performance perk for accessing the internet from school is
that you can take advantage of the wide-area resources leveraged by the
university (vBNS, NREN, Internet2, etc...). Once you go to a third party
ISP you can't be identified as a university member and you loose that
benefit (you have fewer routing choices). The difference is enormous. For
instance, when fetching freebsd code, its much faster to get it all the way
from MIT rather than from the Walnut Creek site in CA, simply because of the
speed of the vBNS connection. This disparity will increase in the future
with I2. Its entirely likely that using your ISP to tunnel through school
(e.g. PPTP) will be faster for many sites that going through your ISP alone.

- Stefan