I am new to Cassandra and learning it. 
So question is how communication is done between nodes in Cassandra 

1. Basic communication - failure detection and other
2. Data transmission from node to node and client
3. Any other type of communication

Answer of 1st one is Gossip protocol <http://www.datastax.com/resources/faq>  

But I am little curious about protocol and methodology Cassandra uses to transfer data from one node to another or client.