[tor-relays] Opt-In Trial: Fallback Directory Mirrors

Sun Dec 20 20:56:58 UTC 2015

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Thanks for the information. The load should be no problem at all,
great to hear ;)

On 20/12/15 14:37, Tim Wilson-Brown - teor wrote:
> 
>> On 20 Dec 2015, at 23:42, NOC <noc at babylon.network 
>> <mailto:noc at babylon.network>> wrote:
>> 
>> Signed PGP part Good to hear the criteria will be reviewed. As
>> far as I am aware there are under-utilised resources on these two
>> exit relays so that is why I am opt-ing in these relays.
>> 
>> If there is any more information on the expected resources for
>> the fallback directory mirrors that will be used I am all ears
>> ;)
>> 
> 
> With 100 fallback directory mirrors, up to an extra 50 GB per
> fallback per month. (This is my estimate of the maximum extra load,
> averaged across 100 fallbacks. But client consensus downloads will
> actually be distributed by the fallback's consensus weight, so
> larger relays may use more.) I suspect most fallback directories
> won't notice the extra load.
> 
> Here are the details:
> 
> At the moment, new Tor clients contact a directory authority to
> download their initial consensus.
> 
> After we release the fallback directory feature, new clients will 
> contact a fallback directory mirror to download their initial
> consensus. (Bridges will also contact fallback directory mirrors,
> as they are designed to behave like clients. Most relays will
> contact an authority.) Clients will choose a fallback using at
> random, weighted based on their consensus weight.
> 
> If a client is on a slow, unreliable, or censored connection, they
> may contact several mirrors before they get a successful
> connection. (However, regardless of the number of connection
> attempts, the consensus download only happens once.) After the
> initial consensus download, clients will choose from the full set
> of directory mirrors in the consensus.
> 
> We expect that most clients will already have a consensus, it will
> only be the new installs that use a fallback directory mirror. So
> if you take the download counts for the new version of Tor Browser,
> multiply by about 1.5MB (the size of a microdesc consensus), then
> distribute that by consensus weight over the fallback directory
> mirrors, that's the extra load we expect to place on each fallback
> directory mirror.
> 
> Alternately, if you take the bandwidth that a directory authority
> uses to serve consensuses to clients, and divide by 11, then that's
> how much we expect a fallback directory mirror to handle on
> average. (There are 9 authorities, and we hope to have 100 fallback
> directory mirrors.)
> 
> Unfortunately, I don't know the number of Tor Browser downloads.
> And while I can see that the authorities use 110 - 230 KB/s of
> bandwidth[0], I don't know how much of that is client consensuses.
> 
> If we assume that the entire authority bandwidth is used for
> client consensuses, then I would expect that a fallback directory
> mirror would use: 110 - 230 / 11 = 10 - 21 KB/s additional
> bandwidth, or an extra 26 - 54 GB per month on average, distributed
> by consensus weight.
> 
> It's worth noting that the entire Tor network already uses 1Gbit/s
> to serve directory documents[1], and first-time downloads for new
> clients are only a fraction of that. So I suspect most fallback
> directory mirrors won't notice the extra load.
> 
> If you're interested in some further background, the original
> proposal is at [2].
> 
> Tim
> 
> [0]: https://globe.torproject.org/ [1]:
> https://metrics.torproject.org/dirbytes.html [2]:
> https://gitweb.torproject.org/torspec.git/tree/proposals/210-faster-he
adless-consensus-bootstrap.txt
>
> 
> 
>> 
>> On 12/20/2015 01:31 PM, Tim Wilson-Brown - teor wrote:
>>> 
>>>> On 20 Dec 2015, at 02:55, NOC <noc at babylon.network
>> <mailto:noc at babylon.network>
>>>> <mailto:noc at babylon.network>> wrote: The initial message
>>>> states that the relays should be non-exit replays. All these
>>>> relays are exit relays with enough resources to spare so I
>>>> would love to see them added. ...
>>>> 
>>>> -- Tim Semeijn
>>>> 
>>> 
>>> Hi Tim,
>>> 
>>> Thanks for opting-in these relays.
>>> 
>>> I didn't realise that there are under-utilised exit relays in
>>> the Tor network. (I was the one who added "not an exit relay"
>>> to the fallback directory criteria.) We'll review the criteria
>>> before we select the final list.
>>> 
>>> Please feel free to opt-in other under-utilised exit relays.
>>> 
>>> Tim
>>> 
>>> Tim Wilson-Brown (teor)
>>> 
>>> teor2345 at gmail dot com PGP 968F094B
>>> 
>>> teor at blah dot im OTR CAD08081 9755866D 89E2A06F E3558B7F 
>>> B5A9D14F
>>> 
>>> 
>>> 
>>> _______________________________________________ tor-relays
>>> mailing list tor-relays at lists.torproject.org
>> <mailto:tor-relays at lists.torproject.org>
>>> https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays
>>
>>> 
> 
>> 
>> -- Tim Semeijn Babylon Network
>> 
>> PGP: 0x2A540FA5 / 3DF3 13FA 4B60 E48A E755 9663 B187 0310 2A54
>> 0FA5
>> 
>> 
>> _______________________________________________ tor-relays
>> mailing list tor-relays at lists.torproject.org
>> <mailto:tor-relays at lists.torproject.org> 
>> https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays
> 
> Tim Wilson-Brown (teor)
> 
> teor2345 at gmail dot com PGP 968F094B
> 
> teor at blah dot im OTR CAD08081 9755866D 89E2A06F E3558B7F
> B5A9D14F
> 
> 
> 
> _______________________________________________ tor-relays mailing
> list tor-relays at lists.torproject.org 
> https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-relays
> 

- -- 
Tim Semeijn
Babylon Network

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