an anecdotal connectivity problem...

Stefan Savage (savage@cs.washington.edu)
Thu, 29 Apr 1999 08:55:48 -0700

We've always suspected that current routing policies could lead to
non-uniform reachability. With the new simultaneous data collected by Eric
we can try to get some idea of how often this happens. However, for now, I
have an anecdotal report:

At 8:00am on April 29th, I was trying to reach www.acm.org from home (I use
@home). I was unable to make a connection from home, but it worked fine
from school at the same time. Here's what I found:

- acm.org is served by alter.net in NYC
- From UW, the route goes to verio, then to sprint (as per out new policy),
then to alternet (still in seattle)

- From @Home, the route goes down to the @Home's POP in the bay, then
switches to ANS. However, at ANS's MAE-WEST router the traceroute dies (one
hop before alter.net's MAE-WEST router).

Clearly, there is a way to get to acm.org, but that choice isn't available
(or just isn't being made) by @home or by ANS.

- Stefan

P.S. This situation lasted for about 45 minutes and then fixed itself (the
route did not change, but now I actually transit from ANS to alter.net...
although the hop from ANS to alter.net adds about 250ms of delay in SFO...
presumably all queuing/contention)