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RE: A use for site local addresses?



Mike Saywell wrote:

> On Tue, Mar 25, 2003 at 12:00:45PM +0100, Jeroen Massar wrote:
> > Leif Johansson wrote:
> > 
> > > Mark Thompson wrote:
> > > 
> > > >  
> > > >
> > > No matter how you capitalize the word, it still needs to 
> run the same
> > > applications! Applications must not know about topology. Period.
> > 
> > I am also *against* Link local.

Not that this meant site local ofcourse as rectified in another message
;)

> > 
> > IP's should be globably unique. Which will overcome many problems
> > like network mergers ('oh we need to NAT now'), e2e problems etc.
> 
> This is very true, but there are certain scenarios (like the 
> network I've described) where we have a need for a large
> number of addresses, which dont require to be globally
> routable (since network is self-contained).

If the network is selfcontained then you neither have to uphold
the rules of the internet relating to address usage. One could
also simply start using 3f00::/8 for your self and nobody should
complain. If you move from your self-contained network to a
internet-connected network then you are bound to renumber anyways.
There is no need to set aside numbering here and as we are talking
about a /10 here that could count up one day.

> If it was possible to use global addresses then I would, however rules
> regarding the IPv6 address space allocation make this a near 
> impossibility for us. :(
> 
> I can't really see the motivations to do NAT under v6 when 
> it's so easy to have multiple addresses on an interface
> anyway. Joining 2 networks which use the same address
> site-local addresses would be nowhere near as painfull
> as before since it's that much easier to re-number one of
> them under v6.

It isn't all that much easier in v6 than in v4 if the site
is using RA or DHCP (IPv4 has DHCP remember :) for configuring
the networks. The 'pain' in renumbering is not the routing nor
making the host get it's new prefix, it's all the databases and
other configuration items that have to renumbered too.
And I won't delve deeper into people using IP addresses in
URL's to 'speed it up a bit' ;)
But fortunatly for IPv6 the guidelines have changed there
and browsers should not support it per default.
Storing IP's in anything but DNS will cause headaches.
One will need it to locate ones nameserver though but
that should be solvable with DHCP and maybe one day
even simple RA's...

And if one is using static IPv4 it has the same pains as static IPv6.
Nothing to work around there either.

Greets,
 Jeroen


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