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Light Hotspot Impact on Validator Traffic

· 5 min read

With HIP 55 the community approved increasing the scope of work and rewards for Validators. This document includes preliminary estimates to help provide further insight into the changes Light Hotspots have on Validator traffic.

The core developers have tagged a new 1.9.1 release. This release is mandatory for all Validators. To earn additional Challenge rewards, Validator Operators must upgrade to 1.9.1 AND open port 8080.

We request Validator Operators upgrade by 00:00 UTC on 2022-05-11.

This will allow the approved HIP 55 chain variable to be activated and prepare for the activation of Light Hotspots.


Upon activation, Light Hotspots are no longer full blockchain nodes and the work plus the rewards of issuing Proof-of-Coverage Challenges are transferred to Validators. For more information about Light Hotspots check the blog.

Light Hotspots will allow the network to operate more smoothly and continue to scale for Hotspot owners as Light Hotspot activation removes the need to sync or relay to stay updated with the Helium Blockchain.

From HIP 55:

"Validator Challenges move the role of generating Challenges to the Validator pool. This not only allows us to free Hotspots from the burden of following the blockchain but it also moves the entities initiating Challenges to machines with much more stable and predictable networking which reduces the likelihood of connectivity failures. Hotspots can become clients of Validators to learn about blockchain updates in general, whether or not they're currently being challenged, and where to deliver Witness receipts."

For more information about HIP 55 visit here:

Light Hotspot impact on Validator network traffic

The team has provided these estimates to help provide further insight into the changes Light Hotspots have on Validator traffic.

Note these are mathematically derived preliminary estimates which the core team will update with additional data as it becomes available.

Block sizes used in these estimates include the following:

  • Non-reward block size = ~600kb
  • Rewards block = ~2000kb
  • Overall average block size (assuming 32 block epoch) = ~645kb

Validator network traffic types:

  • Block Gossip: the entire blockchain or more likely verified snapshots are “gossiped” (shared) to every blockchain node over a peer-to-peer network. As the blockchain becomes bigger, and the number of nodes increases more resources are needed to share snapshots among peers. Light Hotspots are no longer blockchain nodes and so the number of nodes to gossip snapshots is reduced to Validators.

  • Location Gossip: Blockchain nodes routinely gossip the p2p address-to-ip address translation entries stored in their local p2p peerbooks to other nodes. While peerbook entry gossip is significantly smaller than Block Gossip, Validator peerbooks can grow into several hundred thousand entries and the vast majority of the current network nodes (miners) change addresses semi-frequently, requiring a re-gossip. Light Hotspots don't appear in the peerbook or gossip their locations over the p2p network so the absolute possible size of the peerbook will shrink to less than 5K after activation.

  • PoC Challenges (only applies to Light Hotspots): Upon activation, these Challenges are issued by Validators to Light Hotspot Challengees and sent over gRPC vs the peer-to-peer network. Similar to the original design, Challengees will transmit the Challenge packet and Light Hotspots “hearing” the Challenge will serve as Witnesses. However, instead of submitting their Challengee recipients and Witness reports to peer Hotpots, Light Hotspots will submit them via gRPC to the Validator that issued the Challenge via lookup information provided by their connected Validator.

Before Light Hotspots

The amount of network traffic Validators handles is estimated at approximately 31 - 32 GB per day. This includes traffic required for block gossip and location gossip.

After Light Hotspots

After Light Hotspot activation, the amount of network traffic drops to approximately 3.5 to 4 GB per day.

Validator network traffic still includes Block and Location gossip, but also adds Proof-of-Concept (PoC) traffic.

However, with Light Hotspot activation Block gossip lowers the maximum gossip limit to 4 from 32 and the number of locations to gossip from over 700K to less than 5K. In addition, Validators, ETLs, and others change location much less frequently and require fewer updates.

For the new PoC traffic, assuming approximately 150 Light Hotspots per Validator on average running a PoC Challenge approximately every 4 blocks one of them will be challenged, and challenges currently last 20 blocks.

Using 5 blocks at a time at any given moment, conservatively estimate 100kb per PoC works out to 120kb per minute or .17GB per day

Validator Traffic Summary

Here’s a summary of Validator network traffic before and after Light Hotspots.

Block gossip (averaging 1 block per minute * the number of connections)Overall average block size * 32 (max gossip limit) = --- approx. 30GB/dayOverall average block size * 4 (new max gossip limit, just validators) --- approx. 3.5GB/day
Location gossipUnclear, but using ~700k locations to potentially gossip (although confident not often gossiped).Unclear, but gossip universe has reduced to less than 5K entities (majority Validators), so even with 100% saturation this number will be significantly smaller. Also, Validators, ETLs and etc change less often so fewer updates are required.
PoC costN/AApproximately 150 Light Hotspots per Validator on average running a PoC Challenge every 4 blocks. --- Using 4 blocks at a time at any given moment, conservatively estimate 100kb per PoC. --- 100kb per minute or .15GB per day
Total estimated traffic31 - 32 GB/day3.5 - 4 GB/day