When a route is dropped:
The source Replication Server drops all the system table subscriptions created by the destination.
The source Replication Server sends a drop route protocol message to the destination Replication Server.
After this message is delivered to the destination Replication Server (or to the next site, if the route is an indirect route), the source Replication Server drops the route by deleting the entry from its rs_routes system table and, for direct routes, deleting the outbound queue.
The destination Replication Server receives the drop route message and cleans up its part of the route by deleting the locater for the source Replication Server from its rs_locater system table.
