Cassandra works very well in EC2 environment. EC2 doesn't support broadcast/multicast. So, you should be fine.

Thank you,
  Andrey


On Thu, Jun 20, 2013 at 7:22 PM, Jason Tang <ares.tang@gmail.com> wrote:
Hi

   We are considering using Cassandra in virtualization environment. I wonder is Cassandra using unicast/broadcast/multicast for node discover or communication?

  From the code, I find the broadcast address is used for heartbeat in Gossiper.java, but I don't know how actually it works when node communication and when node start up (not for new node added in) 

BRs