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Date: Mon, 1 Jun 2015 09:15:18 -0400
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From: Gavin Andresen <gavinandresen@gmail.com>
To: Alex Mizrahi <alex.mizrahi@gmail.com>
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Subject: Re: [Bitcoin-development] Fwd: Block Size Increase Requirements
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--089e013d101005e33e0517749e4e
Content-Type: text/plain; charset=UTF-8
On Sun, May 31, 2015 at 6:55 PM, Alex Mizrahi <alex.mizrahi@gmail.com>
wrote:
> Yes, if you are on a slow network then you are at a (slight) disadvantage.
>> So?
>>
>
> Chun mentioned that his pool is on a slow network, and thus bigger blocks
> give it an disadvantage. (Orphan rate is proportional to block size.)
>
You said that no, on contrary those who make big blocks have a disadvantage.
> And now you say that yes, this disadvantage exist.
>
>
Did you just lie to Chun?
>
Chun said that if somebody produced a big block it would take them at least
6 seconds to process it.
He also said he has nodes outside the great firewall ("We also use Aliyun
and Linode cloud services for block
propagation.").
So I assumed that he was talking about the "what if somebody produces a
block that takes a long time to process" attack -- which doesn't work (the
attacker just increases their own orphan rate).
If the whole network is creating blocks that takes everybody (except the
person creating the blocks) six seconds to broadcast+validate, then the
increase in orphan rate is spread out over the whole network. The
network-wide orphan rate goes up, everybody suffers a little (fewer blocks
created over time) until the next difficulty adjustment, then the
difficulty drops, then everybody is back in the same boat.
If it takes six seconds to validate because of limited bandwidth, then he
should connect via Matt's fast relay network, which optimize new block
announcements so they take a couple orders of magnitude less bandwidth.
If it takes six seconds because he's trying to validate on a raspberry
pi.... then he should buy a better validating machine, and/or help test the
current pending pull requests to make validation faster (e.g.
https://github.com/bitcoin/bitcoin/pull/5835 or
https://github.com/bitcoin/bitcoin/pull/6077 ).
If Chun had six seconds of latency, and he can't pay for a lower-latency
connection (or it is insanely expensive), then there's nothing he can do,
he'll have to live with a higher orphan rate no matter the block size.
--
--
Gavin Andresen
--089e013d101005e33e0517749e4e
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote">On S=
un, May 31, 2015 at 6:55 PM, Alex Mizrahi <span dir=3D"ltr"><<a href=3D"=
mailto:alex.mizrahi@gmail.com" target=3D"_blank">alex.mizrahi@gmail.com</a>=
></span> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0px=
0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);bor=
der-left-style:solid;padding-left:1ex"><div dir=3D"ltr"><div class=3D"gmail=
_extra"><div class=3D"gmail_quote"><span class=3D""><blockquote class=3D"gm=
ail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left-width:1px;border-l=
eft-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div d=
ir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><div><div>=
<div><span style=3D"color:rgb(34,34,34)">Yes, if you are on a slow network =
then you are at a (slight) disadvantage. So?</span></div></div></div></div>=
</div></div></blockquote><div><br></div></span><div>Chun mentioned that his=
pool is on a slow network, and thus bigger blocks give it an disadvantage.=
(Orphan rate is proportional to block size.)=C2=A0</div></div></div></div>=
</blockquote><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px =
0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-=
style:solid;padding-left:1ex"><div dir=3D"ltr"><div class=3D"gmail_extra"><=
div class=3D"gmail_quote"><div>You said that no, on contrary those who make=
big blocks have a disadvantage.</div><div>And now you say that yes, this d=
isadvantage exist.</div><div>=C2=A0<br></div></div></div></div></blockquote=
><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border=
-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;=
padding-left:1ex"><div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D=
"gmail_quote"><div></div><div>Did you just lie to Chun?</div></div></div></=
div></blockquote><div><br></div><div>Chun said that if somebody produced a =
big block it would take them at least 6 seconds to process it.</div><div></=
div></div><div class=3D"gmail_extra"><br></div><div class=3D"gmail_extra">H=
e also said he has nodes outside the great firewall ("<span style=3D"f=
ont-size:12.8000001907349px">We also use Aliyun and Linode cloud services f=
or block</span></div><span style=3D"font-size:12.8000001907349px">propagati=
on.").</span></div><div class=3D"gmail_extra"><span style=3D"font-size=
:12.8000001907349px"><br></span></div><div class=3D"gmail_extra"><span styl=
e=3D"font-size:12.8000001907349px">So I assumed that he was talking about t=
he "what if somebody produces a block that takes a long time to proces=
s" attack -- which doesn't work (the attacker just increases their=
own orphan rate).</span></div><div class=3D"gmail_extra"><span style=3D"fo=
nt-size:12.8000001907349px"><br></span></div><div class=3D"gmail_extra"><sp=
an style=3D"font-size:12.8000001907349px">If the whole network is creating =
blocks that takes everybody (except the person creating the blocks) six sec=
onds to broadcast+validate, then the increase in orphan rate is spread out =
over the whole network. The network-wide orphan rate goes up, everybody suf=
fers a little (fewer blocks created over time) until the next difficulty ad=
justment, then the difficulty drops, then everybody is back in the same boa=
t.=C2=A0</span></div><div class=3D"gmail_extra"><span style=3D"font-size:12=
.8000001907349px"><br></span></div><div class=3D"gmail_extra"><span style=
=3D"font-size:12.8000001907349px">If it takes six seconds to validate becau=
se of limited bandwidth, then he should connect via Matt's fast relay n=
etwork, which optimize new block announcements so they take a couple orders=
of magnitude less bandwidth.</span><br></div><div class=3D"gmail_extra"><s=
pan style=3D"font-size:12.8000001907349px"><br></span></div><div class=3D"g=
mail_extra"><span style=3D"font-size:12.8000001907349px">If it takes six se=
conds because he's trying to validate on a raspberry pi.... then he sho=
uld buy a better validating machine, and/or help test the current pending p=
ull requests to make validation faster (e.g.=C2=A0<a href=3D"https://github=
.com/bitcoin/bitcoin/pull/5835">https://github.com/bitcoin/bitcoin/pull/583=
5</a> or=C2=A0<a href=3D"https://github.com/bitcoin/bitcoin/pull/6077">http=
s://github.com/bitcoin/bitcoin/pull/6077</a> ).</span></div><div class=3D"g=
mail_extra"><div><br></div><div><div class=3D"gmail_extra"><span style=3D"f=
ont-size:12.8000001907349px">If Chun had six seconds of latency, and he can=
't pay for a lower-latency connection (or it is insanely expensive), th=
en there's nothing he can do, he'll have to live with a higher orph=
an rate no matter the block size.</span></div><div class=3D"gmail_extra"><s=
pan style=3D"font-size:12.8000001907349px"><br></span></div></div>-- <br><d=
iv class=3D"gmail_signature">--<br>Gavin Andresen<br></div>
</div></div>
--089e013d101005e33e0517749e4e--
|
