Why does the IPsec Connection fails to establish at bootup in RHEL5 ?

Issue

• IPsec Connection can't be established at bootup.
• IPsec Connection can't be established if the Server is restarted. The racoon process actually is started regarding output of  'ps -ef | grep racoon' . But the connection deosn't work. The connection works perfectly after a 'ifup ipsec0' while server is running .