I recently tried installing CRS 10.2.0.1 on Oracle's Enterprise Linux (and therefore this applies to any RHEL 4.x clone). As my private and public interfaces are in the private IP address range (RFC 1918) vipca fails at the end of root.sh - that's expected. What has been unexpected was the errors vipca has thrown about halfway through when trying to start the newly created vip resources:

• CRS-1006: No more members to consider and
• CRS-0215: Could not start resource 'ora.dbtest2.vip'

I checked the logfile in $CRS_HOME and found an entry referring to a script called checkIF which complained it could not find a default gateway. Well, I don't need one and with vipca already in the middle of doing stuff it was quite inconvenient. Enter Metalink note Note:356535.1. 

I am pretty sure all these notes are copyrighted so I am not going to explain it in detail here. Only so much: the solution proposed worked. It also explained that these problems can occur when the system administrators change the default gateway addresses without telling the DBAs - no vip starts, the database can't be brought online.