Network Address Translator followup

ISP-TV Main Contact (isptv@access.digex.net)
Wed, 16 Oct 1996 04:22:48 -0400


A better RFC to look at about Network Address Translation (NAT) is
RFC 1631. It claims:

Applications with IP-address Content

Any application that carries (and uses) the IP address inside the
application will not work through NAT unless NAT knows of such
instances and does the appropriate translation. It is not possible or
even necessarily desirable for NAT to know of all such applications.
And, if encryption is used then it is impossible for NAT to make the
translation.

It may be possible for such systems to avoid using NAT, if the hosts
in which they run are assigned global addresses. Whether or not this
can work depends on the capability of the intra-domain routing
algorithm and the internal topology. This is because the global
address must be advertised in the intra-domain routing algorithm.
With a low-feature routing algorithm like RIP, the host may require
its own class C address space, that must not only be advertised
internally but externally as well (thus hurting global scaling). With
a high-feature routing algorithm like OSPF, the host address can be
passed around individually, and can come from the NAT table.

Some NAT vendors have written translators for RealAudio which uses IP
addresses inside the data packet. Does anyone know of a similar translator
for CU-SeeMe, or is NAT not a problem for CU-SeeMe?

-Thomas Edwards
ISP-TV Tech Contact
http://www.digex.net/isptv