From Zaki in: Sentry Node Architecture Overview - #33 by gkrizek
I’ve been thinking that validators should consider adding another type of node to their Architecture- Relay Nodes.
Here is the definition of a Relay node. A Relay Node is a full node that only make connections to sentry nodes of other validators that the operator of the Relay Node. it runs with pex disabled. The firewall on the Relay node blocks all connections from ip address other than what is on a white list.
The Relay node operator will white list the ip addresses of other validators sentries on the relay node firewall and the validators will add the Relay node’s id & ip address to persistent peers.
The presence of a small number of relay nodes could help ensure that consensus operates at maximum efficiency.