> > > echo add 12.0.1.1 255.0.0.0 12.0.0.0 > /net/ipifc/1/ctl > > > echo add 11.0.1.1 255.0.0.0 11.0.0.0 >/etc/ipifc/1/ctl ... > 12 works fine. Pings to 11 don't make it to the medium code. I'm puzzled.
How well does plan9 do multiple IP addresses on the same interface? Could it be that since you added 12.0.1.1/8 *first* by default the source address will be 12.0.1.1? When you ping 11.x.x.x (presumably node1's ip address), your system sends an ARP request to map the ip address to a mac address. Now if the address where ARP response should be sent to is 12.0.1.1, node1 wouldn't know what to do. Can you snoop to see the arp request? What happens if you add addresses in the reverse order? Then 12.x.x.x pings should fail.
