[6bone] Is minimum allocation /64 now?

[Jeroen Massar]

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ipv6@cuhk.edu.hk wrote:

> I am sorry that I am a little bit outdated.  I notice that 
> min allocation
> of address space is /48 instead of /64 in the past for IXes.  I have
> also read some old messages that /64 is used because of automatic
> configuration.

A /48 is per site, if this site is an IX or an end-user or a big
university. /48's are the minimum for every place where there
is a possibility that there is more than one subnet, now or
in the future. Note that bigger entities can ofcourse request
more than a /48, I'd suggest to pass out a /40 in those cases.

If you are absolutely sure that there will only be one subnet
on a certain place you could ofcourse allocate a /64.
But why bother? There is enough space and it would only cost
you more verifications. What if there suddenly is a second,
then they have to renumber, now they won't ever unless they
swap ISP's where to also will get a /48.

>  But then how about P2P?  Is there a practice to use a
> /64 or /127 for P2P link?  Will it break something if I use prefix
> longer than /64?  Thanks for your advice.

Use a /64 for a P2P link it is, as it implies in the name a link.
You could for example use 1 /48 and allocate 65535 P2P links from
that single /48. Keeping it a nice and clean design.
And that is only 1 /48 from the /32 you receive by default, if
you need more then request more.

/127's are bad and go wrong with the anycast address.
We noticed that quite well when Linux 2.4.21 came out
and people started complaining that their endpoints
didn't ping ;)

Greets,
 Jeroen

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