Re: IPv6 static addressing

On 17/03/2018 13:44, Richard Hector wrote:
> Hi all,
> 
> Apologies if this is a bit off-topic, but I know there's lots of IPv6
> knowledge here :-)
> 
> If I have an IPv6 ULA block (or several) 

Why mention ULAs? Your question applies equally to normal (globally routeable, GUA)
addresses. ULA and GUA prefixes are treated exactly the same both in SLAAC and in
DHCPv6.

> using SLAAC, and I want to
> additionally give out some static addresses in one or more of those
> blocks, am I right in thinking I can pick anything I like as long as it
> doesn't have the magic fffe in the middle?

As far as I can see you can pick any valid /128 address in the applicable
/64 prefix. The probability of a clash with a SLAAC-generated address
is minimal, and duplicate address detection works.

I don't see where :fffe: comes in any more, we dropped the model of
making up the interface identifier from the MAC address long ago.
Modern operating systems just use a pseudo-random 64 bits. Generally
people seem to use small integer identifiers for servers.
smtp.gmail.com is 2404:6800:4008:c00::6c for example.

> Is there a more formal approach? Is this (SLAAC plus statics where
> required) the normal way of doing things?

I think so, except for True Believers in DHCPv6, or people who pay good
money for APAM software.

Regards
    Brian