Re: IPv6 Address Planning

[Iljitsch van Beijnum <iljitsch () muada com>]

On 10-aug-2005, at 19:32, bmanning () vacation karoshi com wrote:

>     so renumbering out of a /56 into a /48 is harder than renumbering
>     out of a /124 into a /112 how?

Having a /60 or a /48 is better than a /56 or a /48 because:

1. Most people who are going to encounter the problem realize that a / 
60 isn't enough and go for the /48 immediately
2. Going from a /60 to a /48 would happen earlier than from a /56 to  
a /48 so there is less to renumber.

>     renumbering - regardless of version
>     is hard...

Not hard, inconvenient.

>     primarly becuase application developers insist that
>     the IP address is the nodes persistant identifier,

Disagree. There are two issues: the DNS and access restrictions and  
similar based on IP addresses. The DNS can be fixed with some  
searching and replacing and/or dynamic DNS updates, but using literal  
IP addresses, especially in filters and such, isn't easy to solve  
because there are no reasonable alternatives in many cases.

>     renumbering hosts is a breese in either
>     version of predominate IP protocol, DHCP is your friend.

That friend will kill all your sessions when you get a new address.  
DHCP implementations in IPv6 aren't ready for prime time either.

>     Or if you
>     want less robust functionality and semantic overload, you can use
>     the RA/ND stuff in IPv6.

How is that less robust and does it imply a semantic overload?

>   - regardless, renumbering from one address
>     range to another is painful - CIDR -might- be helpful, but  
> artifical
>     constraints e.g /64 only serve to confuse.

I agree. All boundaries between different parts of the address must  
be flexible. That includes the boundary at the end of the address.  
But I guess we have to save something for IPv7.