P2P Networking

Savitri Network uses libp2p 0.55 for all peer-to-peer communication.

Transport Stack

Layer	Technology
Transport	TCP
Encryption	Noise protocol
Multiplexing	Yamux
Discovery	Kademlia DHT
Pub/Sub	Gossipsub
Identity	Ed25519 peer keys

Gossipsub Topics

Topic	Publisher	Subscriber	Purpose
/savitri/tx/1	Lightnodes	Lightnodes, Masternodes	Transaction broadcast
/savitri/block/1	Lightnodes	All nodes	Block broadcast
/savitri/consensus/cert/1	Lightnodes	Masternodes, Observer	Block acceptance certificates
/savitri/peer_registry/1	All nodes	Masternodes	Peer keepalive / registration
/savitri/lightnode/group/announce/1	Masternodes	Lightnodes	Group assignments
/savitri/group/{id}/election	Group members	Group members	Per-group elections

Gossipsub Configuration

Parameter	Lightnode	Masternode
mesh_n	8	8
mesh_n_high	12	12
mesh_n_low	4	4
mesh_outbound_min	3	3
connection_handler_queue_len	50,000	50,000
max_transmit_size	256 KB	256 KB
flood_publish	false	true (all subscribers)

Message Compression

Format	Status	Use Case
snap	Enabled	General P2P messages
lz4	Enabled	High-throughput paths
zstd	Disabled on MSVC	Not used on Windows

Peer Liveness

Lightnode

• PoU score sharing: Publishes via gossipsub every 60 seconds
• Latency probes: Every 30 seconds via direct P2P
• Heartbeat: Gossipsub publish on /savitri/peer_registry/1

Masternode

• last_seen refresh: Updated on ANY gossipsub message from a peer
• Inactivity timeout: 600 seconds (configurable per MN config)
• cleanup_inactive(): Removes nodes that exceed timeout
• SlowPeer handler: Disconnects peers with saturated send queues

Observer

• 30-second heartbeat: Publishes on /savitri/peer_registry/1
• Subscribes to: /savitri/consensus/cert/1 and /savitri/block/1

Bootstrap

Bootstrap peers are configured in config/bootstrap_nodes.json:

[
  {
    "peer_id": "12D3KooW...",
    "address": "/ip4/3.120.x.x/tcp/4001"
  }
]

Nodes connect to bootstrap peers on startup and discover additional peers via Kademlia DHT.

Direct P2P (Request-Response)

Some operations use direct peer-to-peer communication instead of gossipsub:

Operation	Protocol
Latency probes	Direct request-response
PoU ACK	Point-to-point response
Election candidates	Direct P2P

This avoids O(N^2) broadcast overhead for operations that only need to reach specific peers.

Network Ports

Port	Protocol	Service
4001	TCP	P2P (libp2p) default
8333	TCP	P2P (alternative)
8545	HTTP	RPC (JSON-RPC 2.0)
8546	WS	WebSocket
9090	HTTP	Prometheus metrics

Configuration

config/development.toml

[network]
max_peers = 10
block_time_secs = 2
max_tps = 100
group_size = 3

config/production.toml

[network]
max_peers = 50
block_time_secs = 5
max_tps = 1000
group_size = 7
slashing_enabled = true

Log Filtering

To reduce verbose gossipsub logs:

RUST_LOG=info,libp2p_gossipsub::behaviour=error

This suppresses Send Queue warnings that include full message payloads (1-2KB each, causing 120MB+ logs).