Oracle Database Discussions

SQL> select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

SQL> 
SQL> 
SQL> show parameter db_name

NAME                         TYPE      VALUE
------------------------------------ ----------- ------------------------------
db_name                      string    Oracle11
SQL> show parameter service_names

NAME                         TYPE      VALUE
------------------------------------ ----------- ------------------------------
service_names                        string      primary
SQL> 
SQL> 
SQL> ho
[oracle@primary admin]$ 
[oracle@primary admin]$ cat listener.ora
# listener.ora Network Configuration File: /u01/app/oracle/product/11.2.0/db_1/network/admin/listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = primary)                        ================> Note Here , i asked this parameter .
      (ORACLE_HOME = /u01/app/oracle/product/11.2.0/db_1)
      (SID_NAME = primary)
    )
  )

LISTENER =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.178)(PORT = 1525))
  )

ADR_BASE_LISTENER = /u01/app/oracle

[oracle@primary admin]$ 
[oracle@primary admin]$ 
[oracle@primary admin]$ exit
exit

SQL> 

in my option , i think the value of GLOBAL_DBNAME equal to the value of DB_NAME . But it's wrong , the remote client can't connect the database .
when its value equal to the value of SERVICE_NAMES , the remote client can connect the database .

what's the value of GLOBAL_DBNAME in the listener.ora ?