No outbound load spreading in IPMP on Solaris 11

Hi,

I have an active-active IPMP group setup on my server, defined with 4 interfaces and 3 additional IP addresses (deprecated) for inbound connections.

ipmpstat -na  shows the following (which looks as I would expect)

ADDRESS                   STATE  GROUP       INBOUND     OUTBOUND

::                        down   ipmp0       --          --

10.24.0.7                 up     ipmp0       net3        net5 net4 net3 net2

10.24.0.6                 up     ipmp0       net5        net5 net4 net3 net2

10.24.0.5                 up     ipmp0       net4        net5 net4 net3 net2

10.24.0.4                 up     ipmp0       net2        net5 net4 net3 net2

There is also the persistent route defined:  (shown with route -p show)

persistent: route add 10.24.15.0/24 10.24.0.10

The inbound load appears evenly spread on all interfaces, but the outbound load is all on one interface.  The data sources send from the network 10.24.15.0 to one of the above 4 IP addresses, and the system on this server sends back acknowledgements to the same IP address.