Chris's Wiki :: blog/sysadmin/NetworkUpWhatWeMean Commentshttps://utcc.utoronto.ca/~cks/space/blog/sysadmin/NetworkUpWhatWeMean?atomcommentsDWiki2020-12-08T23:51:09ZRecent comments in Chris's Wiki :: blog/sysadmin/NetworkUpWhatWeMean.By Tony Finch on /blog/sysadmin/NetworkUpWhatWeMeantag:CSpace:blog/sysadmin/NetworkUpWhatWeMean:260aeb0182b7192e6146716887a33f2164c52855Tony Finchhttps://dotat.at<div class="wikitext"><p>Yes, I have also had some issues with IPv6 duplicate address detection. There was a “fun” failure where my DNS server recovered from a power outage faster than its switch, so DAD delayed IPv6 address configuration and BIND failed to listen on IPv6. (I think DAD timed out so the address was never configured.)</p>
<p>My servers have static addresses, so I have now configured them to skip DAD so IPv6 works without an active link in a similar way to IPv4.</p>
</div>2020-12-08T23:51:09ZBy AlanW on /blog/sysadmin/NetworkUpWhatWeMeantag:CSpace:blog/sysadmin/NetworkUpWhatWeMean:83535558714d6ba711623f74a4bc431380d564d9AlanW<div class="wikitext"><p>It's even worse with IPv6 SLAAC addresses. I believe, though haven't yet confirmed, that Duplicate Address Detection causes a delay in the address being set, after the interface is up. This is after "systemd-networkd-wait-online.service" becomes ready. I haven't found anything else provided by systemd to wait for. Some daemons, e.g. ntpd by default and bind/named if the automatic-interface-scan config option is set will scan for interfaces becoming ready.</p>
</div>2020-12-08T08:23:51Z