[arin-ppml] ULA-C and reverse DNS

michael.dillon at bt.com michael.dillon at bt.com
Mon Mar 22 12:19:18 EDT 2010

> I think that it makes far more sense to make a liberal GUA 
> policy that allows people to get GUA if they need it 
> regardless of whether they need it for internet or not.  
> Then, if they want it from a prefix set aside as 
> "non-routable", then, that's available, but, it's a purely 
> advisory semantic, not something coded into systems or 
> routers or whatever.

That is as bad as PA addressing. Your address range is
tainted as unroutable, and if you want to change that,
you have to return the addresses and get a new range
and renumber. 

ULA-C allocations are what they are, and are permanent
allocations. You simply do not use them for traffic
which needs to be routable on the Internet.


Printer1     link local, ULA
Printer2     link local, ULA
FileServer1  link local, ULA
FileServer2  link local, Global Unicast
WebServer1   link local, ULA
WebServer2   link local, Global Unicast
MailServer   link local, ULA, Global Unicast

Everybody has a link local adddress. Things that are only
used inside the org, have a ULA address. FileServer2 is
for customers to upload some data. WebServer1 handles
the company intranet webservices, WebServer2 is the external
Internet webserver. And the Mailserver works for everyone,
everywhere, however they may roam.

--Michael Dillon

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