TCP tunable parameters in Solaris non-global zone

An regular X server requires a display and input devices like a keyboard and a mouse. There are no such devices available on a non global zone and the ones available on the global zone, if any, are likely to be already used and are hardly shareable.

On the other hand, you can either launch a graphic environment on a NGZ with the X server being remote if your goal is to have a desktop running on that zone or you should be able to run one of the virtual X servers available like Xnest, Xvnc, Xvfb and perhaps Xephyr.

My guess is that in the first case, the network stack is sending a ping out on bnx0 and not receiving a reply because bnx1 is not connected to the same network. In the second case, the ping is short-circuited through the network stack so it succeeds immediately.

In general I would not recommend using multiple interfaces on the same subnet in this way. If you need redundancy, use LACP (if your switch supports it) or IPMP. If you need traffic isolation, use a different subnet for bmz1. If you need neither, just add a new virtual interface to bmz0 instead of bmz1.