Re: [bitcoin-dev] [BIP Proposal] New "sendheaders" p2p message

[Peter Todd via bitcoin-dev]

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Hash: SHA512



On 24 September 2015 14:56:23 GMT-04:00, Suhas Daftuar  
wrote:
>I considered that as well, but it seemed to me that other software on
>the
>network (say, different wallet implementations) might prefer the option
>of
>being able to bump up their protocol version in the future to pick up
>some
>other change, without having to also opt-in to receiving
>headers-announcements for blocks.
>
>In particular, inv-based block announcements aren't going away (even in
>my
>implementation of headers announcements, there are some edge cases
>where
>the code would need to fall back to an inv announcement), so forcing
>all
>software on the network to upgrade to supporting headers announcements,
>whether now or in the future, seems too drastic -- I could imagine some
>software not being very concerned about optimizing block relay in this
>particular way.

Block headers are so small - 80 bytes - that it may be reasonable to just stop 
using the inv mechanism for them in favor of always sending headers. IIRC a inv 
is 32 bytes of digest and another four bytes or something of the inv string 
itself - that's already nearly half of the header.

Meanwhile reducing the amount of state in the protocol does have some value, 
and decreasing overall latency for headers to get around the network certainely 
isnt a bad thing.
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Re: [bitcoin-dev] [BIP Proposal] New "sendheaders" p2p message

[Suhas Daftuar via bitcoin-dev]

I considered that as well, but it seemed to me that other software on the
network (say, different wallet implementations) might prefer the option of
being able to bump up their protocol version in the future to pick up some
other change, without having to also opt-in to receiving
headers-announcements for blocks.

In particular, inv-based block announcements aren't going away (even in my
implementation of headers announcements, there are some edge cases where
the code would need to fall back to an inv announcement), so forcing all
software on the network to upgrade to supporting headers announcements,
whether now or in the future, seems too drastic -- I could imagine some
software not being very concerned about optimizing block relay in this
particular way.

On Thu, Sep 24, 2015 at 2:41 PM, Peter Todd  wrote:

> -BEGIN PGP SIGNED MESSAGE-
> Hash: SHA512
>
>
>
> On 24 September 2015 14:37:40 GMT-04:00, Suhas Daftuar via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
> >On Thu, Sep 24, 2015 at 2:17 PM, Tier Nolan via bitcoin-dev <
> >bitcoin-dev@lists.linuxfoundation.org> wrote:
> >
> >>
> >> Is there actually a requirement for the new message?  New nodes could
> >just
> >> unilaterally switch to sending headers and current nodes would be
> >> compatible.
> >>
> >
> >I don't believe that unilaterally switching to headers announcements
> >would
> >work for all network participants -- both for users running older
> >Bitcoin
> >Core versions (anything before 0.10, which I believe all ignore headers
> >messages) and for non-Bitcoin Core software that participates on the
> >network (which may ignore headers messages too, I'm not sure what all
> >is
> >out there).
>
> You can enable the behaviour based on advertised p2p network version.
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>
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Re: [bitcoin-dev] [BIP Proposal] New "sendheaders" p2p message

[Tier Nolan via bitcoin-dev]

On Thu, Sep 24, 2015 at 7:02 PM, Suhas Daftuar via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> Hi,
>
> I'm proposing the addition of a new, optional p2p message to help improve
> the way blocks are announced on the network.  The draft BIP is available
> here and pasted below:
> https://gist.github.com/sdaftuar/465bf008f0a4768c0def
>
> The goal of this p2p message is to facilitate nodes being able to
> optionally announce blocks with headers messages rather than with inv's,
> which is particularly beneficial since the introduction of headers-first
> download in Bitcoin Core 0.10.  In particular, this allows for more
> efficient propagation of reorgs as it would eliminate a round trip in
> network communication.
>

Is there actually a requirement for the new message?  New nodes could just
unilaterally switch to sending headers and current nodes would be
compatible.

It looks like the only DOS misbehaving penalty is if the header is invalid
or if the headers don't form a chain.
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Re: [bitcoin-dev] [BIP Proposal] New "sendheaders" p2p message

[Peter Todd via bitcoin-dev]

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Hash: SHA512



On 24 September 2015 14:37:40 GMT-04:00, Suhas Daftuar via bitcoin-dev 
 wrote:
>On Thu, Sep 24, 2015 at 2:17 PM, Tier Nolan via bitcoin-dev <
>bitcoin-dev@lists.linuxfoundation.org> wrote:
>
>>
>> Is there actually a requirement for the new message?  New nodes could
>just
>> unilaterally switch to sending headers and current nodes would be
>> compatible.
>>
>
>I don't believe that unilaterally switching to headers announcements
>would
>work for all network participants -- both for users running older
>Bitcoin
>Core versions (anything before 0.10, which I believe all ignore headers
>messages) and for non-Bitcoin Core software that participates on the
>network (which may ignore headers messages too, I'm not sure what all
>is
>out there).

You can enable the behaviour based on advertised p2p network version.
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