Bitcoin Core has published an FAQ section regarding the most recent Bitcoin Improvement Proposal (BIP), we are talking about the BIP 152 named Compact Block Relay, the upgrade is poised to reduce the bandwidth and the time it takes for a block to propagate through the nodes across Bitcoin’s network.
The upgrade contains several techniques to decrease a block’s propagation time across the network. The general idea is to take advantage of the fact that full nodes have similar data in their memory pools, thus, a node can only send a sketch of the block to their peers, which will then recreate it, this will save bandwidth as the full block doesn’t have to be transferred.
The block sketch will contain an 80-byte header of the new block, shortened transaction identifiers, and it may also send some other transactions ID which the sending peer predicts the receiving peer doesn’t have yet.
Bitcoin’s core team said in the BIP152’s FAQ:
The advantage of this approach is that transactions only need to be sent once in the best case —when they are originally broadcast—providing a large reduction in overall bandwidth.
Benchmarks of the Upgrade
The upgrade also has a new feature called high bandwidth mode, in which nodes can request the same block