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Date: Mon, 19 May 2014 14:15:54 +0200
Message-ID: <CANEZrP28PQNwuLYTgzyaTDUY-Sg2fEijiPZ26k3NbwvgYoqLww@mail.gmail.com>
From: Mike Hearn <mike@plan99.net>
To: =?UTF-8?B?QmrDuHJuIMOYaXZpbmQgQmrDuHJuc2Vu?= <bo.bjornsen@gmail.com>
Content-Type: multipart/alternative; boundary=089e01184b2894680004f9bfb92e
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] About the small number of bitcoin nodes
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>
> As an interested party not intimately familiar with the bitcoin codebase
> who also spent some time setting up a node a while ago, I would like to
> add one thing to the above list - network rate limiting.


The problem is that this is easier said than done. Bitcoin Core won't
notice a remote peer is working but slow and switch to a faster one, and
even if it did, it'd just mean throttling your connection would cause all
remote nodes to give up and hit the other unthrottled peers even more.

The best way to implement this is to do chain pruning, so your node will
still try and shovel bytes as fast as possible, but it's limited by how
many bytes it has to shovel. Remote nodes that are pulling down the block
chain can then switch between nodes depending on what they have available
in order to try and avoid hitting one node too hard. Nodes that were
offline for a while and just catching up would prefer nodes that have less
of the chain.

It'd be great if someone could experiment with this. The first step is
extending the p2p protocol so addr broadcasts and version messages include
how much of the chain (counting blocks from the head?) the peer is willing
to serve, and then updating the downloading code so it tries to be smarter
about peer selection. Unfortunately all this work is sort of backed up
waiting for sipa to finish merging in headers-first downloading.

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<div dir=3D"ltr"><div class=3D"gmail_extra"><div class=3D"gmail_quote"><blo=
ckquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #c=
cc solid;padding-left:1ex">As an interested party not intimately familiar w=
ith the bitcoin codebase<br>

who also spent some time setting up a node a while ago, I would like to<br>
add one thing to the above list - network rate limiting.</blockquote><div><=
br></div><div>The problem is that this is easier said than done. Bitcoin Co=
re won&#39;t notice a remote peer is working but slow and switch to a faste=
r one, and even if it did, it&#39;d just mean throttling your connection wo=
uld cause all remote nodes to give up and hit the other unthrottled peers e=
ven more.</div>
<div><br></div><div>The best way to implement this is to do chain pruning, =
so your node will still try and shovel bytes as fast as possible, but it=
9;s limited by how many bytes it has to shovel. Remote nodes that are pulli=
ng down the block chain can then switch between nodes depending on what the=
y have available in order to try and avoid hitting one node too hard. Nodes=
 that were offline for a while and just catching up would prefer nodes that=
 have less of the chain.</div>
<div><br></div><div>It&#39;d be great if someone could experiment with this=
. The first step is extending the p2p protocol so addr broadcasts and versi=
on messages include how much of the chain (counting blocks from the head?) =
the peer is willing to serve, and then updating the downloading code so it =
tries to be smarter about peer selection. Unfortunately all this work is so=
rt of backed up waiting for sipa to finish merging in headers-first downloa=
ding.</div>
</div></div></div>

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