bitcoin/bitcoin#16401 - package relay
bitcoin/bitcoin#16702 - asmap to improve bucketing
bitcoin/bitcoin#16974 - Walk pindexBestHeader back to ChainActive().Tip() if it is invalid
bitcoin/bitcoin#16856 - Do not allow descendants of BLOCK_FAILED_VALID blocks to be BLOCK_FAILED_VALID
bitcoin/bitcoin#16939 - p2p: Delay querying DNS seeds if addrman is populated
bitcoin/bitcoin#15505 - p2p: Request NOTFOUND transactions immediately from other outbound peers, when possible
bitcoin/bitcoin#16834 - Fetch Headers over DNS
bitcoin/bitcoin#17428 - p2p: Try to preserve outbound block-relay-only connections during restart (hebasto)
approach: bitcoin/bitcoin#15502 - p2p: Speed up initial connection to p2p network
bitcoin/bitcoin#17194
bitcoin/bitcoin#16562