Filename: set bridge shutdown.txt
Title: Set estimated shutdown time on bridges
Author: Sebastian G. (aka bastik_tor)
Created: 20-JAN-2012
Type: idea

Overview:

   This is about setting the estimated shutdown time of bridges,
   which could be set by bridge operators that don't have
   their bridges run 24/7
      
   It's an rough idea.
   
Motivation:

   Relays should run 24/7, while bridges don't have to.
   Unstable bridges can be a problem in terms of reachability.
   The user experience is bad when two of three bridges go offline.
   
   This should make disappearing bridges more predictable.
   
   It should prevent that one gets bridges that power of 5 minutes
   later.

Design:

   The design assumes:
   - the number of bridges that only run a few hours daily is big enough
   to be a problem.
   
   The bridge operator can set when the bridge will not be available.
   This time should be set farther in the future, when in doubt.
   This can be set for seven days.
   This has to be set in UTC.
   
   When nothing is set full reachability is asumed.
   
   The made settings are passed to the BridgeDB (or it's successor).
   The BridgeDB decides if a bridge will be given out based on
   the time the bridge will be available.
   
   When one appears to be an adversary, he could get only bridges
   that will power off soon.
   
Security implications:

   This idea was not made with security in mind.
   It's not considered harmful.
   
Specification:

   MON_shutdown hh:mm
   TUE_shutdown hh:mm
   WED_shutdown hh:mm
   THR_shutdown hh:mm
   FRI_shutdown hh:mm
   STR_shutdown hh:mm
   SUN_shutdown hh:mm
   
   where hh:mm is UTC   
   
Compatibility:

   Bridges that don't set anything are assumed to be available all
   the time.

Implementation:

   BridgeDB (or it's successor) needs to process the settings and make
   decisions on it.

Performance:

   This should not have any performance impact.
   
Open questions:

    Are there enough unstable relays?
	Do users benefit from it?