This feature is new in the Solaris 10 3/05 release.
Virtual IP source address selection enables a system administrator to specify an IP source address to be used for packets that are routed through a particular network interface. This source address can be hosted on the just-introduced virtual network interface (vni), which is immune to hardware failures. Alternatively, the source address can be hosted on the loopback interface.
You can use virtual IP source address selection in conjunction with IP routing protocols to provide multipathing (that is, redundancy) at the network layer, beyond the first router. Currently, this form of multipathing works in conjunction with the RIPv2 routing protocol that is available in the in.routed daemon.