Proposal: remove down routers from consensus

Nick Mathewson nickm at
Fri Jun 13 01:08:56 UTC 2008

On Thu, Jun 12, 2008 at 10:28:41PM +0200, Peter Palfrader wrote:
> This is a pretty low hanging fruit and part of the job to make tor
> bootstrap faster even if your bandwidth is really small.
> Filename: xxx-remove-down-routers-from-consensus

Added as proposal 138.

This proposal looks simple enough and right enough to me.  I lean
towards accepting.  Any objections?

> 2. Current status
>   At a typical bootstrap a client downloads a 140KB consensus, about
>   10KB of certificates to verify that consensus, and about 1.6MB of
>   server descriptors, about half of which it requires before it will
>   start building circuits.
>   Another proposal deals with how to get that huge 1.6MB fraction to
>   effectively zero (by downloading only individual descriptors, on
>   demand).  Should that get successfully implemented that will leave the
>   140KB compressed consensus as a large fraction of what a client needs
>   to get in order to work.
>   About one third of the routers listed in a consensus are not running
>   and will therefor never be used by clients who use this consensus.
>   Not listing those routers will safe about 30% to 40% in size.

Two related proposals I'd like to see:
  - It would be perhaps be good if clients could download "diffs" for
    consensuses to get only the parts that change from cycle to cycle.
    Of course, the data would need to be signed, and there are issues when 
    a client skips a cycle.  Are you still interested in writing a proposal
    for this? 

  - It's dumb how v3 the v3 directory protocol still depends on the
    existence of v2 directories.  We should fix that.


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