What happens if a validator node “drops out” or unregisters during an epoch?

There is no need for a “buffer” of validator nodes waiting to jump in as Radix consensus does not actually require 100 validator nodes – that’s just the upper limit.

If a node (or several nodes) stops responding for whatever reason, consensus will see that they have timed out and move on. 

Suppose nodes are missing consensus rounds like this. In that case, their emission rewards will rapidly go to zero, and we expect that stakers will quickly remove their stake and allow other validators to move into the top-100. 

As the Radix Public Network does not require 100 validator nodes, and there are strong incentives for stakers to delegate to nodes with high participation in consensus rounds, there is no need to have a set of validators-in-waiting from the perspective of network liveness.

Further reading:

• How should I choose validators to stake to?
• How can validator nodes minimize disruption if they need to leave the network?
• How do validator nodes unstake or unregister?
• Why not incentivize validators below the top-100 as a “buffer”?
• How are nodes outside of the top 100 incentivized to “step in” if any of the top 100 validators drop out?