Entrouter Line

Zero-loss cross-region packet relay network.

Adaptive FEC, encrypted UDP tunnels, real-time latency-mesh routing, and QUIC 0-RTT edge termination. Written in Rust.

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What This Does

Relays packets between globally distributed PoP (Point of Presence) nodes with:

• Zero packet loss up to 10% link loss adaptive Reed-Solomon FEC absorbs all loss with zero throughput impact
• Zero relay overhead measured loss exactly matches simulated network loss, the relay adds nothing
• Optimal routing via real-time latency mesh with Dijkstra shortest-path (not BGP)
• Instant connections via QUIC 0-RTT + TCP splitting at edge
• Always-encrypted tunnels with ChaCha20-Poly1305

Benchmarks

Tested on London ↔ Sydney (273ms RTT) over Vultr shared VPS, one of the longest internet routes on Earth, on budget infrastructure.

FEC Loss Recovery

Link Loss	Throughput vs Baseline	Status
0%	100%	Baseline
5%	100%	Perfect recovery
10%	99%	Perfect recovery
20%	87%	Matches theoretical prediction within 1%
22%	83%	Graceful degradation
25%+	FAIL	QUIC control plane limit (see below)

Relay Overhead

Link Loss	Relay Added Loss
1%	0%
5%	0%
10%	0%
20%	0%

The relay introduces zero additional packet loss at any tested loss level. Encryption, header routing, and tunnel forwarding add no measurable overhead.

Infrastructure Limits (Not Code Limits)

• ~140 Mbps throughput cap: Vultr VPS NIC/bandwidth allocation, not the relay. On bare metal or higher-tier VPS, throughput scales with the NIC.
• 25%+ loss failure: At 25% unidirectional loss over 273ms RTT, each QUIC round-trip faces ~44% compound loss. No QUIC implementation (Quinn, quiche, msquic) survives this. This is a physical link constraint, not a relay limitation. On shorter routes or better infrastructure, the operational ceiling is higher.
• Real-world context: Internet backbone loss between major cities is typically 0.01–2%. This relay handles that range with zero visible loss. Even 10–20% loss (damaged undersea cable territory) still delivers 87%+ throughput.

Full benchmark methodology and raw data: BENCHMARK-RESULTS.md

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Quick Start

1. Build

cargo build --release

2. Configure

Copy the example config and edit for your nodes:

cp config.example.toml config.toml

node_id = "us-east-01"
region = "us-east"

[listen]
relay_addr = "0.0.0.0:4433"
tcp_addr   = "0.0.0.0:8443"
quic_addr  = "0.0.0.0:4434"
admin_addr = "127.0.0.1:9090"

[[peers]]
node_id    = "eu-west-01"
region     = "eu-west"
addr       = "1.2.3.4:4433"
shared_key = "base64-encoded-32-byte-key"

Generate a shared key:

openssl rand -base64 32

3. Run

./target/release/entrouter-line --config config.toml

The admin API is available at http://127.0.0.1:9090:

• GET /health liveness check
• GET /status peer connections, latency matrix, routing table

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Architecture

User → [QUIC 0-RTT] → Edge PoP → [UDP + FEC + ChaCha20 Tunnel] → Edge PoP → Origin

Project Structure

src/
├── main.rs              # Entry point
├── config.rs            # Node & peer configuration
├── relay/               # Core relay engine
│   ├── tunnel.rs        # Encrypted UDP tunnels
│   ├── fec.rs           # Adaptive Forward Error Correction
│   ├── forwarder.rs     # Packet forwarding & routing
│   ├── crypto.rs        # ChaCha20-Poly1305 encryption
│   └── wire.rs          # Binary wire protocol
├── mesh/                # Routing mesh
│   ├── probe.rs         # Latency probing
│   ├── router.rs        # Dijkstra shortest-path routing
│   └── latency_matrix.rs
└── edge/                # Edge termination
    ├── tcp_split.rs     # TCP connection splitting
    └── quic_acceptor.rs # QUIC 0-RTT acceptor

Build

cargo build --release

Contributing

Issues and pull requests welcome. If you're reporting a bug, include:

• Your config (redact keys)
• OS and Rust version
• Steps to reproduce
• Relevant logs

License

MIT — see LICENSE