How much bandwidth does a user use to bootstrap and maintain dir info? How has that changed over time?
We've gone through a series of iterations on the mechanisms for fetching directory info, culminating in these last two:
iteration n-1: "start by fetching a new consensus and all the microdescriptors, and then fetch a new consensus every few hours plus fetch new microdescriptors as needed"
iteration n: like that but use consensus diffs when possible for the new consensus documents
(and we compress some of these steps on the wire)
How many actual bytes is this right now? For the current network, how much are we saving with 'iteration n' over 'n-1'? It would be awesome to track this number over time, so we put ourselves in a position to be able to notice when the load gets higher than we expected.
I ask because we have a large org asking us about the bandwidth tradeoffs of adding 7 figures, 8 figures, or 9 figures of users into the Tor network, and all I have as an answer is my intuitive guess of "about a megabyte per user per day".
I cc komlo since maybe they already computed this metric as part of analyzing related work for walking onions.
And I choose the Tor component since the metrics folks will be happy to graph numbers if the network team exports the numbers, but probably they have no plans to calculate things themselves.