»Consul Enterprise Advanced Federation
This feature requires Consul Enterprise with the Global Visibility, Routing, and Scale module.
Consul's core federation capability uses the same gossip mechanism that is used for a single datacenter. This requires that every server from every datacenter be in a fully connected mesh with an open gossip port (8302/tcp and 8302/udp) and an open server RPC port (8300/tcp). For organizations with large numbers of datacenters, it becomes difficult to support a fully connected mesh. It is often desirable to have topologies like hub-and-spoke with central management datacenters and "spoke" datacenters that can't interact with each other.
Consul Enterprise offers a network area mechanism that allows operators to federate Consul datacenters together on a pairwise basis, enabling partially-connected network topologies. Once a link is created, Consul agents can make queries to the remote datacenter in service of both API and DNS requests for remote resources (in spite of the partially-connected nature of the topology as a whole). Consul datacenters can simultaneously participate in both network areas and the existing WAN pool, which eases migration.