Unicast Discovery


I am new to Elastic search. I am using ElasticSearch-0.90.3 for my search application. I am having 20 nodes in my cluster with multicast disabled and unicast enabled by giving all 20 machine's IP in "discovery.zen.ping.unicast.hosts".

Suppose in near future i want to add new node to the cluster. In such a case how to add the new node's IP to old 20 nodes? Is there any API available for this?? else how to overcome this situation..

Thanks in advance

Ranjith Venkatesan