On one BLE link, a bundle is fragmented to the MTU on the way out and reassembled into the whole bundle at the next hop.

How it works

BLE is passive: devices discover and relay through each other in the background, no pairing, no taps, no setup. That zero-friction meshing is exactly why it's the primary local bearer, and a deliberate trade-off (lower throughput for always-on, invisible reach).
Every node is both BLE central and peripheral; GATT carries discovery, control, and small frames, with a fast L2CAP lane for bulk.
Each bundle is fragmented to the MTUMTU, Maximum Transmission Unit: the largest chunk a link carries in one frame. Bundles are split to fit it and reassembled at the next hop, so message size is never capped by the wire. on the way out and reassembled at the next hop.
BLE is the first bearer, not the only one, the same bundles ride Wi-Fi/LAN and the internet relay too. The network finds many ways.

Why it matters

For developers

Background operation within platform limits, fragmentation, and reassembly are handled for you behind the bearer trait, and because BLE needs no pairing, the mesh forms itself with nothing for users to approve. Choosing which neighbors to hop through is the network layer's job, see hdp.

For business

Runs on the BLE radio already in every phone, no hardware to ship, and because BLE pairs with nothing, the mesh just forms. Nothing for people to configure, connect, or tap through.

Deeper implementation detail is coming in the Hop whitepaper.

← hdp://Direct data channel →

BLE

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