Network Architecture en

Network architecture (direct topology)

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English · 中文: Network-Architecture

Since 2.0.0 Hassium is back on the direct topology: the historical in-process gateway (network core) / seamless master migration / L1 load balancing / UDP data plane / client failover have all been retired (decision record: docs/handoff/handoff-2026-09-04-vanilla-direct-network.md).

What players actually get

Capability	Effect
Smooth push	Per-player per-tick chunk-send cap + backgrounded encode/compress; joins never saturate the main thread
Entity optimization	Distance tiers / hotspot density / packet-budget backpressure / UUID phase stagger; applies to vanilla clients (replication cadence only)
Channel compression	Dictionary ZSTD inside aggregated packets + chunk-push native compression; the vanilla compression layer is never touched
Cache reuse on reconnect	Chunks reused by chunkHash: unchanged = UNCHANGED, changed = DELTA, missing = full fetch

Details: Features.

Current topology: a single vanilla TCP connection

There is exactly one vanilla TCP connection between client and server (the game port). All custom payloads (chunks / entities / business) travel this channel during Play; the vanilla compression layer is never touched.

Public deployments only need to open the game port; there are no gateway / UDP ports.

When both sides install the mod, login/configuration performs one capability negotiation (internal, invisible to players). Clients without the mod take the vanilla path and can join by default (compat.requireClientMod = false).

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Configuration

Current network-related keys (full table in Configuration):

Key	Default	Description
master.enabled	true	Server network-optimization master switch (compression / aggregation / chunk push / entity pacing)
chunk.enabled	true	Client chunk-core master switch (shadow server / cache / lighting)
master.maxChunksPerTick	5	Per-player per-tick chunk-send cap
master.enablePacketAggregation	true	Packet aggregation
master.aggregationMaxWaitTimeMs	50	Aggregation max wait (ms; ACK timeout 5s auto-downgrades to direct send)
master.compressionBlacklist	[]	Third-party packet compression / aggregation exclusion (Hassium control-plane is always hard-coded excluded)
master.entity*	see Configuration	Entity optimization (9 keys, on by default; benefits vanilla clients too)

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