The other end of the tunnel is fubar, who's also a 2.0 kernel on that segment, and has a normal IP address of 192.168.2.23. The result of these gyrations is that copper can send traffic to 192.168.3.1 as 192.168.3.2, and vice versa, without using those addresses on the network. The next step is to set up a similar tunnel between fubar and ozzy. The 2.2 kernel includes both IPv6 over IPv4 tunneling and GRE tunnelling as well as the 2.0 compatible ipip tunnelling. And here's where I am frankly confused at present.
Network is unreachable returns the same kind of error.
This is not correct, however. The point of the excersize for me is to route one subnet across another without allowing the two to actually interact. Now, unlike the 2.0 kernel the 2.2 kernel does install a route automatically upon the address configuration of an interface. The interface address is still reachable without requiring an explicit route as in fubar's setup above. Which will allow fubar to respond to the correct place once I get figured out how to set up ozzy's tunnel end.