Bitcoin's P2P Layer Improvements
Erlay: Bandwidth-Efficient Transaction Relay Protocol
A big boost to the efficiency of Bitcoin nodes, meaning it helps to save a lot of bandwidth. Erlay changes the way transactions are propagated across the network: instead of flooding, it suggests using reconciliation (via minisketch), which allows transmitting much fewer data.
Once deployed, it also allows to increase the security of the network, because we can increase the connectivity while allocating very little extra bandwidth (which was not the case before Erlay). As a side-effect, Erlay also improves privacy at the peer-to-peer layer.
We are working on safely implementing Erlay in the pull request to Bitcoin Core.
asmap: Better Peer Diversification for Bitcoin Nodes
A security improvement for Bitcoin nodes, which allows them to diversify peers they select to connect to, and thus, make attacks harder.
Brought up as mitigation for Erebus attacks, asmap allows choosing nodes based on which Autonomous System they belong to. This forces an attacker to put more effort into creating Sybil entities since now they have to use many Autonomous Systems for their attack.