no circuit loops?
aas23 at hermes.cam.ac.uk
Fri Oct 24 09:55:25 UTC 2003
> But actually, the path choosing code is old and rickety. It still chooses
> the whole path at the beginning, even though the path is actually built
> incrementally. So if any hop fails to build it just gives up.
> It's tricky because we have constraints, such as who can be our exit
> node, that mean we need to think ahead a little bit, so we don't e.g.
> choose the only valid exit node as our second-to-last hop and then look
> around for an exit node.
Surely, you choose from the "other end", right? Assuming the topology is
not restricted, choose the exit node, then choose all the others uniformly
> > On the other hand, the absence of loops gives information about a
> > circuit. E.g., there is an observer on OR_1's network connections.
> > Alice connects through OR_1, OR_2, OR_3, OR_4, OR_5. OR_4 is bad.
> Remember that for performance and usability our path length is actually
> just OR_1, OR_2 by default. So the whole loop question is a bit moot. :)
Yes, but you need to be able to choose paths sensibly if the user alters
the default and the "shortcutting loops" problem is a real one. i.e. you
do not want under any circumstances your first and last router to be the
Cambridge CB3 9ET
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