RE: what problem is solved by proscribing non-64 bit prefixes?

[<michael.dillon at bt.com>]

> When managing such a scheme alongside an IPv6 prefix which 
> needs to be assigned to the same set of servers, which are 
> all dual-stack, the *number* of prefixes, their *relative* 
> numbering, and the host *addresses* within the prefixes, it 
> is quickly apparent that use of only /64 prefixes makes for a 
> management nightmare, particularly if renumbering of prefixes 
> and/or servers occurs, e.g. re-balancing the VLSM arrangement 
> itself in IPv4-land.

Given that in IPv6, you can justify allocating a /48 to each
separate site, which gives you 16 bits to mirror the IPv4
subnet hierarchy, while maintaining 64 bit interface sddresses,
I don't see a technical issue here.

And I would really recommend that you upgrade all of your management
systems to fully support IPv6 instead of relying on tricks like
generating an IPv6 address by applying a transform to an existing
IPv4 address. Then you have no technical issue at all.

--Michael Dillon


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