Path Hash Modes (MeshCore)

Path Hash Modes (MeshCore)

Path hash modes control how repeaters identify themselves in routing path headers within MeshCore packets. This feature is available in recent MeshCore firmware versions. Check your firmware release notes for version-specific availability.

Mode Comparison

Mode	Bytes per Hop	Max Hops	Unique IDs	CLI Setting
1-byte	1	64	254256	set path.hash.mode 0
2-byte	2	32	65,536	set path.hash.mode 1
3-byte	3	21	16,777,216	set path.hash.mode 2

Mode 0 (1-byte) is the default.

Recommendation

Use 2-byte mode (set path.hash.mode 1) for most North American community meshes.meshes (a common community recommendation, e.g. NodakMesh).

• 1-byte mode supportsprovides up256 topossible 254 uniquehash IDs. WithBy the birthday paradox the chance of a collision reaches ~50% at only about 19 repeaters in range (well below 256), so with more than ~30 repeaters in range,range hash collisions become likely, causing routing errors and ambiguous path attribution.
• 2-byte mode supportsprovides 65,536 uniquepossible hash IDs, eliminatingmaking collisioncollisions riskvanishingly unlikely for any realistic community mesh while keeping per-hop overhead to 2 bytes.
• 3-byte mode is future-proof but reduces maximum hop count to 21, which may be limiting in networks with long routing chains.

Mixing path hash modes within a single mesh requires all in-path repeaters to be running firmware ≥ 1.14. On networks where some repeaters run older firmware, keep every device on the same (default) mode.

Configuration Steps

1. Connect to the repeater via USB serial (115200 baud) or Bluetooth
2. Set the desired mode:

   set path.hash.mode 1

3. Broadcast updated hash to the network:

   advert

App Access

PathIn recent companion-app versions (around v1.41.0+; check current release notes, as the menu location may change between versions), path hash mode can also be adjusted in the companion app (v1.41.0+) under:

Settings → Experimental Settings

Note that "Experimental Settings" must be enabled in the app before this option appears.

Network-Wide Consistency

All repeaters and nodes on the same network segment do not need to use the same path hash mode - mode is a per-device setting affecting how that device encodes its own ID in path headers. However, for consistent diagnostics and network analysis, aligning all devices to the same mode simplifies troubleshooting.troubleshooting, and mixing modes requires all in-path repeaters to be on firmware ≥ 1.14 (see above).