What is block propagation?
- Author
- CRYPTO PORT Editorial
- Published
- Updated
- Reading time
- 5 min
In short
Block propagation is how a newly mined block spreads to every node on the network. Slow propagation means two blocks at the same height can appear at once, and one of them ends up discarded. That waste is why most chains implement tricks to cut the amount of data that must travel.
Key points
- How a new block reaches the rest of the network
- Delays make competing blocks at the same height likelier
- Compact relay schemes cut the data that must be sent
- Block size and propagation speed trade off against each other
Definition
The process by which a newly mined or proposed block travels from peer to peer across the network, and by which each node validates and accepts it.
A blockchain has no central server; each node connects to only a few dozen peers. A new block spreads hand to hand from there, and because every node validates before relaying, verification time adds to propagation time.
If another miner finds a block at the same height while the first is still spreading, the network briefly splits in two. One of the blocks is eventually discarded and the work behind it earns nothing. Propagation speed directly determines how much of this waste occurs.
Bitcoin's answer is to send short transaction identifiers first and skip re-sending anything the receiver already holds in its mempool. Other approaches relay while still receiving, or route blocks through dedicated relay networks.
Watch out for
- · Bigger blocks carry more transactions but propagate slower and cause more competition
- · Nodes on slow connections sit at the tail of propagation and are disadvantaged
- · Leaning too hard on relay networks turns them into a single point of failure