10g RAC and firewall

Ave !

One question about application server, firewall and 10g RAC. Can't find exact information from MetaLink :(

So when install RAC in Unix, You should have virtual ip addresses defined
/etc/hosts and You define those also in tnsnames.ora. Right? Then You open a port e.g. 1521 to that virtual ip on firewall.

Question is: Should I open this 1521 on firewall also to primary ip of the RAC node?

             Do RAC use this primary ip e.g. in failover situation or for load balancing?

TIA Jorma

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