In the sample given on the site is said:
Sample VIPA environment in AIX® 5.2
The following sample VIPA environment with Ethernet connections involves a system with a virtual IP address and two physical connections.
A system has a virtual IP address, vi0, of 10.68.6.1 and two physical connections, en1 with IP address 10.68.1.1 and en5, with IP address 10.68.5.1. In this example, both physical connections are Ethernet, but any mixture of IP interfaces, such as token-ring or FDDI, would be supported as long as the subnets were ultimately attached to the larger corporate network and were known to the corporate routers.
Running the lsattr -El vi0 command produces the following results:
netaddr 10.68.6.1 N/A True
state up Standard Ethernet Network Interface True
netmask 255.255.255.0 Maximum IP Packet Size for This Device True
netaddr6 Maximum IP Packet Size for REMOTE Networks True
alias6 Internet Address True
prefixlen Current Interface Status True
alias4 TRAILER Link-Level Encapsulation True
interface_names en1,en5 Interfaces using the Virtual Address True Running the ifconfig vi0 command produces the following results:
vi0: flags=84000041<UP,RUNNING,64BIT>
inet 10.68.6.1 netmask 0xffffff00
iflist : en1 en5 Running the netstat -rn command produces the following results:
Routing tables
Destination Gateway Flags Refs Use If PMTU Exp Groups
Route Tree for Protocol Family 2 (Internet):
default 10.68.1.2 UG 3 1055 en1 - -
10.68.1/24 10.68.1.1 U 0 665 en1 - -
10.68.5/24 10.68.5.1 U 0 1216 en5 - -
127/8 127.0.0.1 U 4 236 lo0 - -
10.68.6.1 127.0.0.1 UH 0 0 lo0 - - The outgoing packets that do not have a source address set and that are routed via interfaces en1 and en5 will have the source address set to the virtual address (10.68.6.1). Incoming packets are routed to the VIPA address (10.68.6.1) advertised on the network. Because vi0 is virtual (that is, not associated with any device) there should be no entries for it in the system-wide routing table displayed using the netstat -rn command. This means no interface route is added when the interface is configured in SMIT.
If one of the physical interfaces, a network attachment, or a network path fails, the network protocols route to the other physical interface on the same system. If a remote system telnets to the vi0 address, packets to vi0 can arrive using either en1 or en5. If en1 is down, for example, packets can still arrive on en5. Note that routing protocols might take time to propagate the routes.
When using the VIPA, the end systems and intervening routers must be able to route the packets destined for VIPA (vi0) to one of the physical interfaces (en1 or en5).
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Shouldn't you have set the default router you would have for physical interface(s)?