[arin-ppml] ULA-C and reverse DNS

Michael Richardson mcr at sandelman.ca
Mon Mar 22 15:15:38 EDT 2010

Hash: SHA1

>>>>> "michael" == michael dillon <michael.dillon at bt.com> writes:
    >> 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.

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

I think that this is something to repeat multiple times.

I think that a lot of people regard address space as so valuable that it
would be crazy to "waste" it by having two IPs addresses on a single

This is where I think the notion that people will pay $$$$ to have their
address space routed by ISPs. It won't happen --- getting new PA will be
almost free, and getting PI address space is a nominal charge given that
you have $$$$ for that bribe.

    michael> Everybody has a link local adddress. Things that are only

Alas, link-local addresses are not as easy to use as you might think.
They are specific to a link, and IPv6 implementations insist that you
tell the kernel which link they are specific to, so applications
actually need to grow additional mechanisms to set that.
Some OSes have included textual representations in their pton routines
to set this properly, not it's not universal in the APIs.

It's a rare organization (or even residential home with a wifi router)
that has only one physical link --- many do extensive amounts of L2
bridging (and then filtering of broadcasts) to deal with scarcity of
IPv4, and lack of mobility. 

In IPv6 it really makes no sense to do this --- make them seperate L3
subnets and use properly scoped multicast to do service locating.

- -- 
]       He who is tired of Weird Al is tired of life!           |  firewalls  [
]   Michael Richardson, Sandelman Software Works, Ottawa, ON    |net architect[
] mcr at sandelman.ottawa.on.ca http://www.sandelman.ottawa.on.ca/ |device driver[
   Kyoto Plus: watch the video <http://www.youtube.com/watch?v=kzx1ycLXQSE>
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