Subject: Re: [Bitcoin-development] BIP to improve the availability of blocks

From: Peter Vessenes <[email-masked]>
Date: Mon, 30 Apr 2012 13:54:37 -0700

Blocks already checksum; they hash to a low number.

Also inre: block headers, you are furnished with a previous hash in the
first 80 bytes of the block. You can always cut the connection at that
moment if you've already seen the block headers.

Peter

On Mon, Apr 30, 2012 at 1:02 PM, Zell Faze <[email-masked]> wrote:

> Although quite true, I actually agree though that there should be some
> sort of checksum for the blocks.  Bandwidth may not be a bottleneck now (or
> ever), but it may be at some point.  This change will help Bitcoin scale.
>
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> --- On Mon, 4/30/12, Amir Taaki <[email-masked]> wrote:
>
> > From: Amir Taaki <[email-masked]>
> > Subject: Re: [Bitcoin-development] BIP to improve the availability of
> blocks
> > To: "[email-masked]" <
> [email-masked]>
> > Date: Monday, April 30, 2012, 3:11 PM
> > This is optimisation where it isn't
> > needed. Bandwidth is not the bottleneck of the Bitcoin
> > system. It is the immense time needed to validate the
> > blockchain.
> >
> > And clients should never send blocks first. They always send
> > an inv packet, then you request the block. It is a
> > disruptive change and brings little.
> >
> > We don't need to optimise every aspect of Bitcoin :) Just
> > focus on the big bits that matter, while keeping everything
> > working with minimal changes.
> >
> > For instance say we did this and to maintain backwards
> > compatible, we introduced a new message called "hash+block".
> > Now there are 2 code branches that must be maintained -
> > urgh.
> >
> >
> > ________________________________
> > From: Wladimir <[email-masked]>
> > To: Rebroad (sourceforge) <[email-masked]>
> >
> > Cc: [email-masked]
> >
> > Sent: Monday, April 30, 2012 7:26 PM
> > Subject: Re: [Bitcoin-development] BIP to improve the
> > availability of blocks
> >
> >
> > On Mon, Apr 30, 2012 at 6:40 PM, Rebroad (sourceforge)
> > <[email-masked]>
> > wrote:
> >
> >
> > >My proposal is that in addition to the size (which is
> > advertised in
> > >the header), the hash is also advertised in the header
> > (of a block).
> > >This would help nodes to determine whether they wanted
> > to reject the
> > >download. (e.g. if it already had a block matching that
> > hash). This of
> > >course wouldn't prevent a rogue node from sending an
> > incorrect hash,
> > >but this would aid in saving bandwidth amongst behaving
> > nodes.
> > >
> >
> > I suppose it would make sense for clients to be able to
> > reject blocks that they already have, if that's not
> > currently possible.
> >
> >
> > The other part of the proposal is to allow nodes to request
> > upload and
> > >download blocks that have already been partially
> > downloaded.
> > >
> > >This could be done by modifying the existing methods of
> > upload,
> > >download, or by adding a new method, perhaps even using
> > HTTP/HTTPS or
> > >something similar. This would also help nodes to obtain
> > the blockchain
> > >who have restrictive ISPs, especially if they are being
> > served on port
> > >80 or 443. This could perhaps also allow web caches to
> > keep caches of
> > >the blockchain, thereby making it also more available
> > also.
> > >
> >
> > You don't need a BIP if you want to somehow fetch the
> > (initial) block chain
> > outside the bitcoin protocol. You could download it from
> > some http
> > server or even pass it along on an USB stick. Then with a
> > simple client change you can import it:
> https://github.com/bitcoin/bitcoin/pull/883 .
> >
> >
> > Currently, without this functionality, nodes with
> > restrictive (or
> > >slow) internet have some options, such as going via a
> > tor proxy, but
> > >due to the latency, the problem with multiple receptions
> > of the same
> > >block still occur.
> > >
> >
> > If you're behind such a slow internet connection, and
> > concerned about
> > every bit of bandwidth, it is better to run a lightweight
> > node. For example, Electrum.
> >
> > Even if you could reduce the wasted bandwidth a bit by
> > puzzling
> > around with partial blocks, the download will still be
> > substantial (and that's going to get worse before it gets
> > better).
> >
> > Wladimir
> >
> >
> >
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Peter J. Vessenes
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