PerformanceWiki [the blog]

bash-3.00# db2start
05/15/2007 15:01:59     0   0   SQL5043N  Support for one or more communications protocols failed to start

successfully. However, core database manager functionality started successfully.
SQL1063N  DB2START processing was successful.

look into db2diag.log:

2007-05-15-15.01.58.846394-420 E92034A447         LEVEL: Error
PID     : 405708               TID  : 1           PROC : db2sysc 0
INSTANCE: db2inst1             NODE :
000
FUNCTION: DB2 UDB, common communication, sqlcctcpconnmgr, probe:50
MESSAGE : ADM7006E  The SVCENAME DBM configuration parameter was not
          configured.  Update the SVCENAME configuration parameter using the
          service name defined in the TCP/IP services file.

2007-05-15-15.01.59.901248-420 E92482A1028        LEVEL: Event
PID     : 397514               TID  : 1           PROC : db2star2
INSTANCE: db2inst1             NODE : 000
FUNCTION: DB2 UDB, base sys utilities, DB2StartMain, probe:911
MESSAGE : ADM7513W  Database manager has started.
START   : DB2
DBM
DATA #1 : Build Level, 152 bytes
Instance “db2inst1″ uses “64″ bits and DB2 code release “SQL09012″
with level identifier “01030107″.
Informational tokens are “DB2 v9.1.0.2″, “s070210″, “U810940″, Fix Pack “2″.
DATA #2 : System Info, 224 bytes
System: AIX fnl70 3 5 00CE3A8A4C00

The error is caused by a black SVCNAME in the database manager settings.
You can validate this by running the following command:

bash-3.00# db2 get dbm cfg | grep -i svc
 TCP/IP Service name                          (SVCENAME) =

Find out what’s defined in /etc/services:
bash-3.00# grep -i db2 /etc/services
ibm-db2          523/tcp                #
IBM-DB2
ibm-db2          523/udp                # IBM-DB2
questdb2-lnchr  5677/tcp                # Quest Central DB2 Launchr
questdb2-lnchr  5677/udp                # Quest Central DB2 Launchr
DB2_db2inst1    60000/tcp
DB2_db2inst1_1  60001/tcp
DB2_db2inst1_2  60002/tcp
DB2_db2inst1_END        60003/tcp

To fix this, update the dbm cfg using that value in /etc/services; in this case DB2_db2inst1:

bash-3.00# db2 update dbm cfg using SVCENAME DB2_db2inst1
DB20000I  The UPDATE DATABASE MANAGER CONFIGURATION command completed
successfully.
bash-3.00# db2stop
force
05/15/2007 15:31:57     0   0   SQL1064N  DB2STOP processing was successful.
SQL1064N  DB2STOP processing was successful.
bash-3.00# db2start
05/15/2007 15:32:02     0   0   SQL1063N  DB2START processing was successful.
SQL1063N  DB2START processing was successful.

This SOLVED the SQL5043N problem.

.pw.