Re: IPv6 fc00::/7 — Unique local addresses

Fri Oct 22 01:33:56 UTC 2010

On Oct 21, 2010, at 3:15 PM, Mark Andrews wrote:

> 
> In message <E22A56B3-68F1-4A75-A091-E416800C485B at delong.com>, Owen DeLong write
> s:
>>>>> 
>>>> Which is part one of the three things that have to happen to make ULA
>>>> really bad for the internet.
>>>> 
>>>> Part 2 will be when the first provider accepts a large sum of money to
>>>> route it within their public network between multiple sites owned by
>>>> the same customer.
>>>> 
>>> 
>>> That same customer is also going to have enough global address
>>> space to be able to reach other global destinations, at least enough
>>> space for all nodes that are permitted to access the Internet, if not
>>> more. Proper global address space ensures that if a global destination
>>> is reachable, then there is a high probability of successfully reaching
>>> it. The scope of external ULA reachability, regardless of how much
>>> money is thrown at the problem, isn't going to be as good as proper
>>> global addresses.
>>> 
>> _IF_ they implement as intended and as documented. As you've
>> noted there's a lot of confusion and a lot of people not reading the
>> documents, latching onto ULA and deciding ti's good.
>> 
>> It's not a big leap for some company to do a huge ULA deployment
>> saying "this will never connect to the intarweb thingy" and 5-10 years
>> later not want to redeploy all their addressing, so, they start throwing
>> money at getting providers to do what they shouldn't instead of
>> readdressing their networks.
> 
> IPv4 think.
> 
> You don't re-address you add a new address to every node.  IPv6 is
> designed for multiple addresses.
> 
That's a form of re-addressing. It's not removing the old addresses, but,
it is a major undertaking just the same in a large deployment.

>>> For private site interconnect, I'd think it more likely that the
>>> provider would isolate the customers traffic and ULA address space via
>>> something like a VPN service e.g. MPLS, IPsec.
>>> 
>> One would hope, but, I bet laziness and misunderstanding trumps
>> reason and adherence to RFCs over the long term. Since ULA
>> won't get hard-coded into routers as unroutable (it can't),
> 
> Actually it can be.  You just need a easy switch to turn it off.  The
> router can even work itself out many times.  Configure multiple interfaces
> from the same ULA /48 and you pass traffic for the /48 between those
> interfaces.  You also pass routes for that /48 via those interfaces.
> 
If you have an easy switch to turn it off, it will get used, thus meaning that
it isn't hard coded, it's just default.
> 
Owen