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Dev Docs: Add Section About Headers-First IBD #736

merged 2 commits into from Feb 20, 2015


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@harding harding commented Feb 5, 2015


This adds a short section describing headers-first Initial Block Download (IBD) to the developer guide. This was originally part of pull #660, but it has been substansially rewritten. (And, I hope, improved.) Specifics:

  • Add flowchart illustration to blocks-first section to match new headers-first flowchart
  • Add new headers-first (IBD) section
  • Revise Block Broadcasting section to describe non-IBD block transmission workflow
  • Add paragraph about how headers-first avoids handling orphan blocks to the Orphan Blocks section

* Add flowchart illustration to blocks-first section to match new
  headers-first flowchart

* Add new headers-first initial block download (IBD) section

* Revise Block Broadcasting section

* Add paragraph about orphan block handling in headers-first to the
  Orphan Blocks section
{% include helpers/ %}

{% autocrossref %}

At the start of a connection with a peer, both nodes send `getblocks` messages containing the hash of the latest known block. If a peer believes they have newer blocks or a longer chain, that peer will send an `inv` message which includes a list of up to 500 hashes of newer blocks, stating that it has the longer chain. The receiving node would then request these blocks using the command `getdata`, and the remote peer would reply via `block`<!--noref--> messages. After all 500 blocks have been processed, the node can request another set with `getblocks`, until the node is caught up with the network. Blocks are only accepted when validated by the receiving node.
Bitcoin Core 0.10.0 uses a initial block download (IBD) method called
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@harding s/a initial/an initial/ maybe?

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saivann commented Feb 19, 2015

@harding Very clear, thanks!

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harding commented Feb 19, 2015

@saivann thanks! I fixed the typo you found.

In the absence of critical feedback, this pull will be merged around 13:00 UTC Friday.

@harding harding merged commit 3d7ba83 into bitcoin-dot-org:master Feb 20, 2015
@harding harding deleted the headers-first branch February 25, 2015 01:49
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2 participants