Proposal: remove down routers from consensus

[Nick Mathewson]

On Fri, Jun 13, 2008 at 10:11:02AM +0200, Peter Palfrader wrote:
 [...]
> >   - It's dumb how v3 the v3 directory protocol still depends on the
> >     existence of v2 directories.  We should fix that.
> 
> Agreed.  I wonder if we should just use the vote documents to learn
> about new servers, or if we need a new type of document.

Using the vote _format_ makes sense, but I don't think we want to just
look at the vote documents that we're exchanging now.  Otherwise, it
takes two cycles for authorities to agree.  Here's a timeline of what
would happen if we just looked at the vote documents:

  0:10: A router uploads a descriptor to authority A, but not
        authority B or C.

  0:15: [A starts putting information about the router in its v2
        descriptor, but B and C aren't looking at that.]

  0:50: Voting time!  A, B, and C exchange votes.  A's vote reflects
        the new descriptor, but B and C's votes don't.  B and C
        finally learn about the new descriptor, but since they already
        voted, they can't go back and change their votes to include
        it, even if they did have time to test the new router.

  1:50: Voting time again.  This time, all the authorities now about
        the new router, and things go well.


Perhaps we can have a new value for the vote-status field, for interim
network opinions that authorities can exchange in advance of the
actual voting.

yrs,
-- 
Nick