[tor-relays] sustained bandwidth drop through noisetor

[Andy Isaacson]

noisetor-01 was pushing 300-400 Mbps of traffic from 2012-02-15
through 2012-04-13.  Since mid-April we've seen traffic decrease
significantly; over the last week, our daily peak has been 260 Mbps
(versus 450 Mbps in March) and our daily trough has been 100 Mbps
(versus 300 Mbps in March).

The traffic levels dropped off in a smooth fashion over a 10 day period,
April 15-25 if I read the graphs correctly.

There's no sign that anything is amiss on the node; CPU and memory usage
are consistently lower, today, than they were in March -- as expected,
given the lower utilization.  The logs are silent.

I've been postprocessing torstatus's Tor_query_EXPORT.csv regularly, and
it appears that the overall exit throughput of the network has gone up
slightly over the last few months; some new significant nodes came
online during 2012Q1 and may have affected the traffic distribution.
However, while noisetor has seen a significant drop, other families of
exit nodes have seen their bandwidth go up or stay steady.

Has there been a change in the routing algorithm, or any other network
changes that might explain this drop?

Thanks,
-andy