There is no need for a “buffer” of validator nodes waiting to jump in as the unsharded form of Cerberus consensus supporting the Babylon Mainnet 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 (Liquid Stake Unit token holders) 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 are validators on Radix selected?
- How are nodes outside of the top 100 incentivized to “step in” if any of the top 100 validators drop out?
- What happens if a validator node “drops out” or unregisters during an epoch?