Comment 2 for bug 1447715

I understand that binding to ipv6 addresses that haven't finished Duplicate Address Detection causes the bind() to fail.

http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/ suggests using IP_FREEBIND:

       IP_FREEBIND (since Linux 2.4)
              If enabled, this boolean option allows binding to an IP
              address that is nonlocal or does not (yet) exist. This
              permits listening on a socket, without requiring the
              underlying network interface or the specified dynamic IP
              address to be up at the time that the application is trying to
              bind to it. This option is the per-socket equivalent of the
              ip_nonlocal_bind /proc interface described below.