Hello, not a big problem but would like to hear your opinion. IPv6 knows the status of "deprecated" addresses, that is an address that still can be used to receive but shouldn't be used for initiating sessions anymore (RFC 2462). On FBSD 4.8 you can configure the deprecated flag manually with the ifconfig command. But some neighbor discovery code kicks in short afterwards and deletes the flag :{ The code is: /* * A new RA might have made a deprecated address * preferred. */ ia6->ia6_flags &= ~IN6_IFF_DEPRECATED; Hmm. Obviously the code writers have a dynamic preferred/deprecated control in mind. I think that having a manual equivalent isn't too bad and perfectly valid when you want to renumber a static setup. Comments? Does a manual setting makes no sense? (why?) Maybe this detail was discussed somewhere else and you can give me a hint? Or is the code above missing something is should cover? Regards, Marc (playing around with all the knobs in place ;) )