Colleen Morrow discusses endpoints and routes in Service Broker:
One of the first questions you might ask when distributing Service Broker solutions across multiple machines is “how does SQL Server know where the other service is?” And that’s where routes come in. When we distribute a Service Broker solution, we use routes to tell SQL Server the server name and endpoint port of a remote service on the network.
For example, in our taxes solution, we would create a route in the Taxpayer database that points to the IRS service, and a route in the IRS database that points to the Taxpayer service
Good stuff. A big part of Service Broker’s value is its ability to communicate across servers, not just databases on the same instance.