RFC 1597 Revisited

In "Live Wire" (August BYTE), I discussed the pros and cons of using non-unique IP addresses to form private corporate networks. Use of the 192.1.1 Class C network for this purpose is an Internet folk tradition, I said. RFC 1597 proposes instead to reserve one Class A network, 16 Class B networks, and 256 Class C networks for non-unique addressing.

Why isn't 192.1.1 one of the Class C networks that RFC 1597 proposes to reserve? Well, you can't always trust folk traditions. As it turns out, 192.1.1 is a registered network. Walter "Doc" Urbaniak, a network engineer with BBN Corporate Telecommunications, contacted me to set the record straight.

For years, 192.1.1 has been registered to Bolt, Beranek, and Newman. Urbaniak says that because 192.1.1 is widely but wrongly believed to be available for testing, BBN doesn't even try to use it anymore. "We even found some instances in which vendors were shipping hardware preconfigured for the 192.1.1 network," he adds.

He agrees that private IP networking can be a useful thing, endorses RFC 1597, and configures his own routers not to accept those networks as sources from the Internet. "However," he says, "I wish people wouldn't just assume that 192.1.1 -- and also 192.1.2 and 192.1.3 [also registered to BBN] -- are test city."