[Bitcoin-development] Squashing redundant tx data in blocks on the wire

Gregory Maxwell gmaxwell at gmail.com
Thu Jul 31 23:18:38 UTC 2014

On Thu, Jul 31, 2014 at 3:27 PM, Kaz Wesley <keziahw at gmail.com> wrote:
>> the FEC still lets you fill in the missing transactions without knowing in advance all that will be missing.
> I don't see why we need to solve that problem, since the protocol
> already involves exchanging the information necessary to determine
> (with some false positives) what a peer is missing, and needs to
> continue doing so regardless of how blocks are transmitted.

False positives, and if you have more than one peer— false negatives.
(or a rule for what you must keep which is conservative in order to
avoid creating huge storage requirements— but then also has false

> As far as I can tell, channel memory sparseblocks achieve most of the
> possible bandwidth savings, and when FEC-based mempool synchronization
> is implemented its benefits can be applied to the sparseblocks by
> resetting the channel memory to the mutual mempool state each time
> mempool differences are exchanged. Am I missing a benefit to doing FEC
> at block forwarding time that can't be realized by FEC-based mempool
> synchronization, implemented separately from channel-memory based
> index-coding?

Yes, minimizing latency in the face of multiple peers.

Otherwise no. And certantly no reason to to implement something simple first.

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