>>>I have NetBSD 1.6.1RC3 installed and I noticed following behaviour in
>>> autoconfiguration. The autoconfigured addresses dissapears every once
>>> and a while for a few seconds. What I noticed was that this happens
>>> every time the address has been configured for a valid life time
>>>although the host has received a number of router advertisements during
>>> this time.
>>
>> 	the basic suggestion is, as documented in rtadvd(8), do not have
>> 	rtadvd.conf and let rtadvd(8) determine what prefix to be advertised
>> from interface configuration in the kernel.  use rtadvd.conf only when
>> you are sure really about it.
>
>But if I'll remove the prefix from the rtadvd.conf then the rtadvd will
>advertise the prefix with it default valid life time and with default
>preferred life time which are 2592000 and 604800 seconds although I still
>have a valid life time of 60 seconds and preferred life time of 30 seconds
>in the rtadvd.conf. That's why I have defined the prefix in the
>rtadvd.conf in order to be able to change the valid and preferred life
>time of the prefix.

	ok.  but the values you have chosen are way too short.  i don'
	recommend such a setting.

itojun