Not Enough Bandwidth Fabric

The mod works in two places on the network path. It replaces the long packet identifiers in CustomPacketPayload encoding with a compact VarInt index, which reduces the header overhead of each mod packet to a fixed three or four bytes. It also gathers many small packets that vanilla often sends into one larger packet, held for up to 20 milliseconds before it is compressed with Zstd.

Chunk data is handled differently as well. A player who walks away from a chunk and back normally receives the full chunk again, so the mod delays forgetting chunks and keeps cached chunk data in a local LevelDB database on the client. The client sends a Bloom Filter of its cached chunk hashes to the server, which then sends only a 20-byte hash in place of a 10 to 20 KB chunk the client already holds. The filter is refreshed after every 64 newly cached chunks, and a false positive falls back to a full data request.

Not Enough Bandwidth Fabric requires Fabric API. It runs on the client and the server, so both need it. Files are published for Fabric only, across 8 release versions 1.20.1 – 26.2, under the GNU General Public License v3.0 only, and the project is open source.