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Re: IPv6 Address Planning

  • From: Iljitsch van Beijnum
  • Date: Wed Aug 10 15:27:53 2005 
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.