On each system in the cluster, use the more command to check the file /etc/services.
Remember to perform the following:
Make sure each partition has a port number assigned. The number of reserved ports depends on the number of partitions.
Make sure that no other services use the ports. Manually assign new numbers if necessary.
Make sure all systems in the cluster have the same entries in the /etc/services file.
The following is an example for two DB2 instances: db2inst1 and db2inst2. Both instances have two partitions each. Each instance requires two ports plus one port per partition, hence four lines per instance.
# more /etc/services DB2_db2inst1 60000/tcp DB2_db2inst1_1 60001/tcp DB2_db2inst1_2 60002/tcp DB2_db2inst1_END 60003/tcp DB2_db2inst2 60004/tcp DB2_db2inst2_1 60005/tcp DB2_db2inst2_2 60006/tcp DB2_db2inst2_END 60007/tcp
Inspect the file and verify that no duplicate port numbers exist.