Subject: Re: [RRG] Renumbering...

From: Iljitsch van Beijnum <[email-masked]>
Date: Thu, 14 Aug 2008 11:30:32 +0200

On 14 aug 2008, at 6:49, Dino Farinacci wrote:

>> Are we talking v4 or v6? For v6, we've always tried to project the
>> idea that renumbering, or rather adding and dropping prefixes, should

> I was referring to both. Renumber in both cases is still a pain.  
> Stateless auto-configuration in IPv6 doesn't help renumber routers,  
> switches, and firewalls at the site.

Some years ago I did some testing with a Cisco router as a DHCPv6 PD  
client. The delegated prefix is stored in a variable of sorts which  
can then be used to number _some_ things on the router. This makes  
renumbering the router very easy. Also remember that routing protocols  
work on link local addresses in IPv6, so interior routing shouldn't  
care, but BGP would still be somewhat problematic. I guess it would be  
possible to use ULA addressing for iBGP and of course eBGP would have  
to be renumbered manually anyway.

The problem with firewalls are the rules that allow/disallow remote  
entities based on their address, so local renumbering doesn't matter  
but remote renumbering does. The only workable solution here would be  
to move away from address based access control.

> But staticly addressed servers will need planned outage.

Renumbering a server isn't much harder than renumbering a client  
(stateless autoconfig works for those, too), but unfortunately  
software may react badly to being renumbered so a small interruption  
may indeed be necessary. Back in the day the authoritative DNS servers  
were always the most time consuming to get renumbered in all the  
registries but I gather that's easier these days.

But renumbering does get easier the more often you do it.  :-)

So either avoid it completely or make it a routine thing, the middle  
ground is where the most pain is.

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