On 17/03/18 15:36, Brian E Carpenter wrote:
On 17/03/2018 13:44, Richard Hector wrote:
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
Fair call - I had more or less assumed that, and was contemplating doing
the same thing for the GUA addresses assigned by Vodafone (FibreX) -
except that prefix is dynamic. But I know my knowledge is incomplete,
and the general rule of asking questions on lists is to provide whatever
info might be useful.
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.
is 2404:6800:4008:c00::6c for example.
Ok - I clearly need a better source of current IPv6 info than arbitrary
web search results :-) Any tips? Hmm, perhaps
is a good start.
I notice that all my addresses do have fffe in them though, and at a
quick glance are based on the MAC address (Linux - debian stretch).
Maybe there's a feature I need to enable.
net.ipv6.conf.eth0.use_tempaddr looks like it; presumably it won't argue
with my static allocations.
What happens with the duplicate address detection? The SLAAC one tries
again, and my static one stays put?
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.
Great, thanks a lot :-)