Setting up private Tor network with the real one

[Michael_google gmail_Gersten]

In general, you can't, and don't want, different directory servers
telling you about different nodes. Imagine what would happen if one
directory server was compromised, and told you about a set of attacker
nodes.

Now, one place where this setup becomes interesting is if you have a
separate network -- either the corporate internet, or some variation
of IP V8 (maybe a very large ISP, like China, decides to use their own
network numbering with a translating boarder). Then, you could have
two sets of directory authorities, for two sets of destination IP
ranges -- one set of directory authorities for these IP's, and a
different one for those IP's. Then, you might wind up building two
tunnels, one to get to the gateway, and a second to traverse the
second network on the other side.