You have to perform the following steps:

(1) Register a wrapper.
   A wrapper is nothing else than a library that implements the glue code
   between the DB2 engine and the remote data source.  In your case, the
   remote data source happens to be the same machine/DB2 instance.
   DB2 comes with wrappers for all DB2 and Informix data sources.  I'll
   have to purchase WebSphere Information Integrator for other systems.
(2) Register a server.
   A server identifies a remote data source.  This is a single database in
   DB2 terminology.  In your case, we're talking about 'DB_1' (or 'TEST1').
(3) Register a user mapping.
   The user connected to the federated server (where you want to create
   the nickname) may not be allowed to access the remote data source.
   Thus, you have to define the credentials that shall be used when
   accessing the data source.  (And those credentials are specific for each
   user connecting the federated server.)
(4) Register a nickname.
   A nickname is just a pointer referring to a table at the remote data
   source.

Here is an example that should work for you, assuming that RMT_DB is the
name of the remote database:

CREATE WRAPPER drda;

CREATE SERVER srv
  TYPE DB2/UDB
  VERSION '8'
  WRAPPER drda
  AUTHORIZATION "stolze" PASSWORD "passwd"
  OPTIONS (DBNAME  'rmt_db');

CREATE USER MAPPING FOR USER SERVER srv
  OPTIONS ( REMOTE_AUTHID 'stolze', REMOTE_PASSWORD 'passwd' );

CREATE NICKNAME n FOR srv.syscat.views;

SELECT * FROM n;