direct routes and SLAAC addresses

[George Ross]

> What distribution are you using?

Scientific Linux 7.8 (7.9 soon).

> How do you configure the interfaces?

By adding the relevant lines to the ifcfg-vlanNNN files.

> You can also use a sysctl config file in /etc/sysctl.d to set ...

Yes, we do all that, or at least that's what the init-scripts do.  But as I 
said, there's a race condition.  The interfaces are set so that they 
shouldn't auto-configure, but there's time between the interfaces appearing 
and them being configured not to auto-configure, and that's enough time for 
them to acquire SLAAC addresses, at least sometimes.

As for why we want static addresses when we could just as easily use the 
SLAAC ones, mostly we do just use SLAAC addresses and have our DNS 
provisioning system generate the AAAA and PTR entries for them.  But for 
these particular machines we definitely don't want to have a dependency on 
some other bit of kit to transmit the RAs.  And we definitely don't want to 
have to try to debug routing issues a couple of weeks after some other 
change or breakage.
-- 
George D M Ross MSc PhD CEng MBCS CITP
University of Edinburgh, School of Informatics,
Appleton Tower, 11 Crichton Street, Edinburgh, Scotland, EH8 9LE
Mail: gdmr at inf.ed.ac.uk   Voice: 0131 650 5147 
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The University of Edinburgh is a charitable body, registered in
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