Assuming you can ping, do you see anything different with iptables
turned off?

*sigh* I should have tried turning iptables off -- I can now see both nodes. Thanks :)

That being said, I'm no expert in iptables rules. This is what I added for cassandra, what rules do others use?

-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 9160 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 7000 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 7001 -j ACCEPT
-A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 8888 -j ACCEPT

Cheers,
Chris