Raft and the Consul RPC API use TCP, Serf uses both TCP and UDP. While the Consul RCP API may have grown options to use GRPC (I forget now), Raft uses length-p

Raft and the Consul RPC API use TCP, Serf uses both TCP and UDP. While the Consul RCP API may have grown options to use GRPC (I forget now), Raft uses length-prefixed msgpack PDUs.