Failover IPv6 with multiple PA prefixes (Was: IPv6 fc00::/7 - Unique local addresses)

Karl Auer kauer at
Tue Nov 2 08:25:34 CDT 2010

On Tue, 2010-11-02 at 23:23 +1030, Mark Smith wrote:
> Prefix lifetimes don't work that way - there is no such thing as a
> "flash" renumbering.

The lifetimes are reset with every RA the nodes see. If I reconfigure my
router to start sending out RAs every N seconds, it will take a a
maximum of N seconds for a new preferred lifetime to be established on
all active nodes on the link. If the new preferred lifetime is zero, any
addresses in the prefix will be deprecated immediately, causing other
prefixes on the link to be preferred.

The new valid lifetime will be the remaining valid lifetime (if less
than two hours), the newly advertised valid lifetime (if using SEND), or
two hours in all other cases.

That seems pretty close to "flash renumbering"... at least for SLAAC.
DHCPv6 needs more planning.

Regards, K.

Karl Auer (kauer at                   +61-2-64957160 (h)                   +61-428-957160 (mob)

GPG fingerprint: B386 7819 B227 2961 8301 C5A9 2EBC 754B CD97 0156
Old fingerprint: 07F3 1DF9 9D45 8BCD 7DD5 00CE 4A44 6A03 F43A 7DEF
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
URL: <>

More information about the NANOG mailing list