[arin-ppml] IPv6 Non-connected networks

John Santos JOHN at egh.com
Mon Feb 22 12:19:44 EST 2010

On Mon, 22 Feb 2010 michael.dillon at bt.com wrote:

> > It seems like we're back to ULA again.  It seems that we all 
> > want the same thing, "unroutable" address space for internal 
> > use only.  There are any number of reasons to have RFC 
> > 1918'ish space in v6 and the real difference now is that, 
> > given the size of the v6 address space, we don't have to 
> > allocate blocks to be used by all providers.  Instead, we're 
> > in a position where we *can* give everyone their own block.
> > 
> > We could even do the old multicast thing and auto-assign a 
> > ULA (or whatever it's called) block to each ARIN allocation.  
> > In thinking about it, I do agree that having a defined block 
> > for filtering purposes is preferred.
> GLOP addressing uses the 16-bit ASN to specify a /24 block 
> of multicast addresses, if I remember correctly. So, if we
> used the 32-bit ASN to specify a /48 block of private use
> addresses, we could probably fit it in. 
> I don't believe that this has ever been proposed before
> so it may be worthwhile writing a draft to see what happens.
> And why not also include the "assigned ULA" addresses in 
> the draft as well. If people like one idea better than the
> other, then simplify the draft.
> So we would have
> 16 bits defined prefix for private use IPv6 addresses
> 32 bits ASN number
> 16 bits subnetting space
> 64 bits IIDs
> Total 128 bits of IPv6 address.
> And given that there are some private-use ASNs defined, that
> gives everyone the option to use those private-use addresses
> whether or not they have an assigned ASN. That is essentially
> the same as RFC 1918 addresses in IPv4.
> --Michael Dillon

People with private networks may not/probably don't have ASNs.

Same for people with legacy class "C" addesses that upstreams
refuse to route, but which are extemely useful for private internets
because they can't collide with customer/vendor/peer internal addresses,
unlike RFC1918.

John Santos
Evans Griffiths & Hart, Inc.
781-861-0670 ext 539

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