# File lib/mongo/auth/ldap/conversation.rb, line 64
        def start(connection = nil)
          if connection && connection.features.op_msg_enabled?
            selector = LOGIN.merge(payload: payload, mechanism: LDAP::MECHANISM)
            selector[Protocol::Msg::DATABASE_IDENTIFIER] = Auth::EXTERNAL
            cluster_time = connection.mongos? && connection.cluster_time
            selector[Operation::CLUSTER_TIME] = cluster_time if cluster_time
            Protocol::Msg.new([], {}, selector)
          else
            Protocol::Query.new(
              Auth::EXTERNAL,
              Database::COMMAND,
              LOGIN.merge(payload: payload, mechanism: LDAP::MECHANISM),
              limit: -1
            )
          end
        end