One more thing came to my mind overnight: it is important to note, that SC uses regular IP for inter-node communication, the addresses and subnets are pre-defined (may be changed) and are: 172.16.0.0/21.
As you can see the subnet is rather short resulting in large subnet beign used, the subnets behave like any other IP addresses on the system: they pop up in system's routing table and may ,,hide'' other routes. Please refer to:
Private Network (Sun Cluster Software Installation Guide for Solaris OS) - Sun Microsystems