[tor-dev] Per-transport bridge bandwidth and bridge counts

[David Fifield]

On Sat, Jul 11, 2015 at 12:18:07PM -0700, David Fifield wrote:
> I made some graphs that show the count and total bandwidth of all
> bridges, broken down by transport.
> 	https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-11/pt-bandwidth.png
> 	https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-11/pt-count.png
> The top part of the graph is non-default bridges, and the bottom is
> default bridges (the ones that ship with Tor Browser). Note the varying
> vertical scales. Source code and data are here:
> 	https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-11.tar.gz
> 	https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-11/pt-bandwidth.csv
> 
> I have a question about getting bandwidth numbers. What I want is
> something like available bandwidth capacity; i.e., how much headroom
> transports have given their level of use. I think that the bandwidth
> numbers I'm using are partially conflated with usage. Notice how parts
> of pt-count.png are flat while pt-bandwidth.png has a weekly pattern.
> 
> Yet another option is the speed of serving consensuses, the
> "dirreq-v3-tunneled-dl" line in a bridge-extra-info document:
> 	dirreq-v3-tunneled-dl complete=13624,timeout=1456,running=4,min=1938,d1=21008,d2=43181,q1=53397,d3=63519,d4=88911,md=117048,d6=146982,d7=180109,q3=199979,d8=223313,d9=298860,max=1558627
> You can take the "md=" field, for example, to get median B/s for serving
> consensuses.

I tried extracting extracting the rate of serving consensuses as a
proxy for bridge bandwidth. The "bandwidth" one is the one you saw
before, summing observed bandwidth of bridges. "dl.md" is the median
download rate of consensuses, and "dl.max" is the maximum.

https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-20/pt-count.png
https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-20/pt-bandwidth.png
https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-20/pt-dl.md.png
https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-20/pt-dl.max.png

Source code:
https://people.torproject.org/~dcf/graphs/pt-bandwidth-2015-07-20.tar.gz

These plots omit all bridges that did not have a "dirreq-v3-tunneled-dl"
line.

The new graphs have a different shape than the observed-bandwidth one,
at least. They still seem somewhat tied to usage. It looks like there is
a weekly cycle in the dl.max one--it could be simply that with more
users connecting during the week, the bridge has a higher chance of
seeing a fast one that pushes up the maximum.