[tor-bugs] #2536 [Tor Relay]: Disable outgoing token bucket and reduce token bucket refill interval

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#2536: Disable outgoing token bucket and reduce token bucket refill interval
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 Reporter:  karsten      |          Owner:                    
     Type:  enhancement  |         Status:  needs_review      
 Priority:  normal       |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Relay    |        Version:                    
 Keywords:               |         Parent:                    
   Points:               |   Actualpoints:                    
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Changes (by Flo):

 * cc: tschorsch@… (added)


Comment:

 > Removing the outgoing token bucket entirely is not okay with me, for the
 reasons discussed on the or-dev thread, so I'm going to treat this as
 preliminary.

 In order to meet Nick's comments, here a round-up of a modification
 (http://archives.seul.org/or/dev/Feb-2011/msg00038.html) of our original
 proposal (http://archives.seul.org/or/dev/Jan-2011/msg00004.html) that we
 posted some time ago on or-dev:

 We propose to continue using a token bucket on the incoming side to limit
 the incoming rate anyway. It will also be easy to monitor (not limit!) the
 outgoing rate. We might make use of these two mechanisms to proceed as
 follows: Every time traffic is generated in our relay we remove a
 corresponding amount of tokens from the bucket on the *incoming* side.
 Thereby slowing down the rate at which data flows into the router.

 It is easy to see that it will limit the outgoing traffic to the
 configured limit -- while at the same time it does not need any rate
 limiting mechanism on the outgoing side (it therefore avoids any double-
 door effects). It is also reasonably simple and will thus (hopefully) not
 cause undesired side effects.

 If you agree with this modification, I would love to implement the
 changes.



 > Is it possible to separate the more frequent refill interval part of
 this from the double-door part?  They seem like they should be logically
 separable.

 Both enhancements are sperated in our implementation already.  They can be
 configured by two new parameters: DisableOutgoingTokenBucket and
 TokenBucketRefillInterval. Nevertheless we recommend to use both, since
 using smaller refill intervals only will amplify the double-door effects.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/2536#comment:2>
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