The Stellar Consensus Protocol (SCP) is defined as the implementation of the Federated Byzantine Agreement (BFA) Protocol. The instances of blocked agreement can be minimized using SCP. They can even be neutralized with the help of a ballot system. The SCP consists of the nomination protocol and the ballot protocol.
Producing candidate values for each consensus slot is a purpose of the nomination protocol. A convergence value for each consensus slot is created by every node at the last. Nodes can’t know about the occurring of convergence. The nomination process can be reset by malicious nodes. If nodes agree that the convergence of the nomination protocol has done, then the ballot protocol will be performed. A ballot and a candidate value are connected in the ballot protocol. A node has to either commit or abort the candidate value in the ballot protocol. If nodes abort certain votes and move further, then agreement blocking will be avoided. A ballot is committed by voting. The candidate value is externalized.
Some highly complex details are contained by the nomination protocol. They aren’t only contained by the nomination protocol, but they are also contained by the ballot protocol. The details are contained by both the protocols for the purpose of splitting votes.
A dispensible set mechanism helps to bypass befouled nodes which depend upon bad nodes at the extreme level. Statements can be ratified without the involvement of the befouled nodes. The befouled nodes don’t have the capacity to undermine a consensus.
The way of treating each consensus slot separately by the SCP at a high-level isn’t different from a single-slot consensus in Paxos. Paxos is defined as a group of protocols designed to solve a consensus in the network of unreliable processors. No blocked states are present with quorum intersection in the SCP. The safety can be guaranteed in the situation where adequate quorum slices are selected by nodes and this is the limitation of the SCP. Widely trusted nodes can take disadvantage of their positions and this is a security issue in SCP.