VIPA considerations with source address selection

If SOURCEVIPA is configured for the outbound interface and the application did not request that SOURCEVIPA is to be ignored (by way of the Ignore Source VIPA socket option), the source address is selected from the addresses of the SOURCEVIPA interface. Otherwise, the source address is selected from the addresses of the outbound interface. Selection of a source VIPA address for IPv6 is done differently from IPv4. It is determined by the SOURCEVIPAINTERFACE parameter that is configured on the outbound interface, rather than the order of the HOME list.

When a socket is used to establish a TCP connection to an IPv6 destination or to send a UDP or RAW IP datagram to an IPv6 destination, the local address of the socket is determined based on the set of rules listed in Table 1:

Table 1. Source address selection
Source address selection for communication to IPv6 destinations		TCP, UDP, and RAW
IPCONFIG6 NOSOURCEVIPA	1. The socket is bound to a local IPv6 address.	Do not change the local address, use it as it is.
IPCONFIG6 NOSOURCEVIPA	2. The socket is unbound; it is bound to the unspecified IP address.	Use the IPv6 default source address selection algorithm (selecting an IPv6 address on the physical interface over which the IP packet is about to be sent).
IPCONFIG6 SOURCEVIPA	1. The socket is bound to a local IPv6 address.	Do not change the local address, use it as it is.
	2. A setsockopt() with the NOSOURCEVIPA option was issued for the socket.	Use the IPv6 default source address selection algorithm (selecting an IPv6 address on the physical interface over which the IP packet is about to be sent).
	3. A SOURCEVIPAINTERFACE parameter is configured on the IPv6 INTERFACE definition for the interface over which the IP packet is about to be sent.	Use the IPv6 default source address selection algorithm to select an IPv6 VIPA address from the IPv6 virtual interface pointed to by the SOURCEVIPAINTERFACE parameter.
	4. A SOURCEVIPAINTERFACE parameter is not configured on the IPv6 INTERFACE definition for the interface over which the IP packet is about to be sent.	Use the IPv6 default source address selection algorithm (selecting an IPv6 address on the physical interface over which the IP packet is about to be sent).