Providing Security is mandatory in reliable group communication over open networks in order to prevent intruder attack. To provide privacy and integrity in group communication, the members of the group generates a common secret key called group key for the entire group and it can be used for encrypting the messages in group communication. A distributed key management framework based on dynamic decentralized group key agreement protocol is used for generating the group key. Different Tree based protocols like TGDH, STR can be used for group key generation and group key distribution. For dynamic groups, Rekeying should be done for every new member comes or existing member goes out.