Networking

XE is a fully peer-to-peer network with no central servers. All node communication -- block propagation, consensus voting, synchronization, marketplace negotiation, and peer discovery -- happens over direct connections between nodes using libp2p.

Components

Component

Purpose

Protocol / Mechanism

Host

TCP transport, connection management, persistent identity

libp2p core

GossipSub

Broadcast blocks, votes, marketplace, statechain, directory

libp2p GossipSub

Sync

Frontier-based block synchronization

/xe/sync/1.0.0 stream

Messaging

Request-response over streams

/xe/msg/1.0.0 stream

DHT

Kademlia peer discovery

/xe prefixed DHT

Architecture Overview

┌──────────────────────────────────────────────────────────┐
│                       Node                               │
│                                                          │
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────────┐  │
│  │   Ledger    │  │ State Chain │  │   Directory     │  │
│  └──────┬──────┘  └──────┬──────┘  └───────┬─────────┘  │
│         │                │                  │            │
│  ┌──────┴────────────────┴──────────────────┴─────────┐  │
│  │              Network Layer (net package)            │  │
│  │                                                    │  │
│  │  ┌──────────┐ ┌──────┐ ┌──────────┐ ┌───────────┐ │  │
│  │  │ GossipSub│ │ Sync │ │Messenger │ │    DHT    │ │  │
│  │  └────┬─────┘ └──┬───┘ └────┬─────┘ └─────┬─────┘ │  │
│  └───────┼──────────┼──────────┼──────────────┼───────┘  │
│          │          │          │              │           │
│  ┌───────┴──────────┴──────────┴──────────────┴───────┐  │
│  │           libp2p Host (TCP transport)              │  │
│  └────────────────────────┬───────────────────────────┘  │
└───────────────────────────┼──────────────────────────────┘
                            │
                       TCP / Internet

How Data Flows

Block Propagation

1. A node creates a new block (send, receive, claim, lease, etc.)
2. The block is added to the local ledger
3. The block is published via GossipSub on the xe/blocks topic
4. All subscribed peers receive the block, validate it, and add it to their ledgers
5. If the block triggers a conflict, votes are broadcast on xe/votes

Synchronization

When a new node joins or reconnects after downtime, it uses the sync protocol to catch up:

1. On connection to a peer, the node sends its current frontiers (latest block per account)
2. The peer compares frontiers and streams back any missing blocks
3. A periodic re-sync every 10 seconds catches blocks missed during gossip

Peer-to-Peer Messaging

The messaging protocol provides request-response semantics for targeted communication:

• Marketplace negotiation (resource requests and offers)
• State chain synchronization
• Any typed message exchange between specific peers

Discovery Mechanisms

Peers find each other through three mechanisms:

1. mDNS -- Automatic local network discovery. Nodes on the same LAN find each other without configuration.
2. Bootstrap peers -- Explicit peer addresses passed via the -dial flag. The node retries failed connections every 10 seconds.
3. Kademlia DHT -- Distributed hash table for discovering peers by their peer ID. Used by the Messenger to locate peers not already in the peerstore.

[!INFO] No Central Infrastructure XE has no tracker servers, seed nodes, or central coordination points. Any node can bootstrap from any other node. The DHT protocol prefix /xe isolates the XE network from public IPFS DHT traffic.

Security Properties

• Transport encryption: libp2p provides encrypted connections by default (Noise or TLS 1.3)
• Peer identity: Each node has a persistent Ed25519 identity key, giving it a stable peer ID across restarts
• Message validation: GossipSub pre-validates field lengths before accepting messages
• Rate limiting: Sync protocol enforces a 5-second cooldown per peer to prevent abuse
• Size limits: All protocols enforce maximum message sizes to prevent memory exhaustion

Source Code

The networking layer lives in the core/net/ package:

File

Contents

host.go

Host creation, mDNS discovery, peer dialing

gossip.go

GossipSub for all broadcast topics

sync.go

Frontier-based block synchronization

msg.go

Request-response messaging protocol

dht.go

Kademlia DHT setup

messages.go

Wire format types for all message types