Dear Tor developers,

As a PhD student in distributed systems, I am studying onion routing.

We would like to investigate an onion routing system that would run on users devices, i.e. a lot of nodes with crappy bandwidth and intermittent connection.
To compare against Tor, I have been looking for information about how you currently handle the disconnection of relays, but I found no "digest" on the Web. Your code seems to point to the direction of core/or/circuit*, that I need to investigate further. I still would love some first-hand high-level description from you guys.

I have the following questions:

• When an OR disconnects while supporting active circuits, how is the failure detected?
• How are the paths subsequently rebuilt?
  
• To which extent would you say that Tor is resilient to churn? What would be the effects of a massive churn of relays? Where would be the bottleneck?
  

If you have any questions on my work, I will be pleased to answer (though a little ashamed, because I know our system will never hold your security properties so tight)!

With much respect for your work and philosophy,
Adrien Luxey