MeshCore 2-Byte Path Hash

Switching MeshCore Repeaters to 2-Byte Path Hash

Quick Reference Guide

Choose 2-byte mode () for the best balance of collision prevention and packet payload efficiency. While 3-byte mode offers over 16 million unique IDs, 2-byte mode provides 65,536 IDs—which solves the high collision rate of 1-byte legacy mode without consuming as much overhead or running into minor trace limitations seen in 3-byte implementations. [1, 2, 3, 4, 5]

Comparison of Path Hash Modes

• 1-Byte Mode (): Legacy default, 254 IDs, high collision risk in dense networks.
• 2-Byte Mode (): Recommended sweet spot, 65,536 IDs, efficient payload size.
• 3-Byte Mode (): Over 16 million IDs, but heavier payload footprint and minor tool quirks (like path tracing restrictions). [1, 2, 3, 4]

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See also: Why You Should Switch to 2-Byte Path Hashes in MeshCore (And How Easy It Is) https://tennmesh.com/blog/2byte-path-hashes/

[1] https://nodakmesh.org/blog/meshcore-path-hash-explained

[2] https://blog.meshcore.io/2026/03/06/path-diagnostics-improvements

[3] https://github.com/meshcore-dev/MeshCore/blob/main/docs/faq.md

[4] https://github.com/meshcore-dev/MeshCore/issues/2735

[5] https://www.reddit.com/r/meshcore/comments/1uizjk8/is_there_a_plan_to_make_client_apps_default_path/

Switching to multi-byte path hashes is highly recommended once a regional mesh grows beyond 30 to 40 repeaters to prevent routing collisions.

A path hash is a truncated fingerprint of a repeater’s public key.By default, MeshCore uses a 1-byte hash, which limits the network to 254 unique repeater IDs.If two repeaters in the same region share the same 1-byte hash, packets can be routed in the wrong direction, causing dropped direct messages and failed acknowledgments.

Because the path data in a MeshCore packet is capped at 64 bytes, increasing the size of the hash directly reduces the maximum number of hops a packet can take:

Mode	Size	Max Hops	Unique IDs	Collision Risk
0 (Default)	1-byte	64	254	High in dense meshes
1 (2-byte)	2-byte	32	65,536	Effectively zero
2 (3-byte)	3-byte	21	16,777,216	Zero

Prerequisites

• Repeater Firmware:Must be running MeshCore v1.14.0 or newer.
• Companion App: Must be updated to v1.41.0 or newer to properly parse multi-byte hashes in the receive log.

How to Switch via CLI

The most reliable way to change this setting is through a serial command line interface directly to the repeater.

1. Establish a serial CLI connection to your repeater over USB.
2. Run the following command to set the hash mode to 2-byte:
   Bashset path.hash.mode 1
3. (Optional) If you ever need to revert to 1-byte hashes, run set path.hash.mode 0. For 3-byte hashes, use set path.hash.mode 2.

Once enabled, the repeater will automatically encode its 2-byte prefix into the path field of all forwarded packets.

Compatibility Note: It is perfectly safe to enable path.hash.mode 1 on any repeater running firmware 1.14+.Because the hash size is encoded directly into the upper bits of the packet’s path_length byte, receiving nodes instantly know how to parse the route—no network-wide negotiation is required.

See also: Why You Should Switch to 2-Byte Path Hashes in MeshCore (And How Easy It Is) https://tennmesh.com/blog/2byte-path-hashes/

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