On Friday, April 5, 2002, at 08:42 AM, [EMAIL PROTECTED] wrote: > [I wrote:] >> Also, I think it would be helpful to know how commonly twice-NAT is >> deployed, but I don't have any data there. > > I believe (at least) twice-NAT is fairly common. I have a NATting router > between by cable access modem and my home's local area network, and my > cable access provider has a NATting router between the cable access > network and the public internet. [...]
I should clarify that I was using the term "twice-NAT" as defined in section 4.3 of RFC 2663 "NAT Terminology and Considerations" which actually describes quite a different thing altogether. Begin excerpt: > Twice NAT is a variation of NAT in that both the source and > destination addresses are modified by NAT as a datagram crosses > address realms. This is in contrast to Traditional-NAT and Bi- > Directional NAT, where only one of the addresses (either source or > destination) is translated. [...] Your scenario (which is in the same category as my scenario and the scenario in Appendic C) is not named anywhere I can find. If it has no name yet, I would propose "compound NAT" or something similar. I think it's important to distinguish that we're not talking about a type of NAT here, but rather a way of composing a topology of address realms using multiple instances of potentially different types of NAT. (Ick-- I feel dirty just writing that phrase.) -- j h woodyatt <[EMAIL PROTECTED]>
