classful routes redux

Wed Nov 9 04:19:24 UTC 2005

Thus spake <Michael.Dillon at btradianz.com>
>> ... which is why I specifically said "no intention to ever connect to,
>> or communicates with nodes on, the global network". In which case
>> overlaps in adressblocks are irrelevant, as are any mention of NAT and
>> firewalls as there is no connection (direct or indirect) between the
>> networks.
>
> The only case that I am aware of where there is truly
> *NO* intention to ever connect to the global Internet
> is military networks. When I was referring to other
> internets I did not have military networks in mind.
>
> In every other case that I am aware of, the partcipants
> in the internet also maintain connectivity to the Internet
> via alternate paths.

I've personally dealt with private networks that had no intent of ever 
connecting to the Internet, though they were connected to other internal 
networks that did have such connectivity and to business partners (over 
private links) that probably did as well.

One I still have nightmares about was a mess of eight (yes, eight) instances 
of 10/8 which were dynamically NATed to class B addresses to reach common 
servers and for communication to various partners, with a few tens of 
thousands of static NAT entries for devices that needed to be polled.  I 
suppose if those private networks had had a default route (they didn't) and 
there were no firewalls in the way (there were) they could have reached the 
Internet, but at the time it was designed there was no intent to ever allow 
such.

Too bad the equipment we had to support didn't understand IPv6, or we could 
have gotten away with using the site-local prefix (or, later, ULAs) and no 
NAT at all.

S

Stephen Sprunk        "Stupid people surround themselves with smart
CCIE #3723           people.  Smart people surround themselves with
K5SSS         smart people who disagree with them."  --Aaron Sorkin 