why rtsold ?

[Yuri Pankov]

alan somers wrote:
> On Sat, Sep 29, 2018, 11:24 PM Victor Sudakov <vas at mpeks.tomsk.su> wrote:
> 
>> Alan Somers wrote:
>>>>
>>>> When running FreeBSD as an IPv6 host im SLAAC mode, is
>>>> "rtsold_enable=YES" really necessary? I did not enable rtsold and IPv6
>>>> still works fine only with
>>>>
>>>> fconfig_re0=""
>>>> ifconfig_re0_ipv6="inet6 accept_rtadv"
>>>>
>>>> What would be the point of enabling rtsold then?
>>>
>>> The router may send a router advertisement whenever it wants.  That's why
>>> your machine seems to work even without rtsold.  However, SLAAC addresses
>>> expire after a certain amount of time.  rtsold will ask the router for a
>>> new advertisement before your address expires.  You aren't guaranteed to
>>> have problems if you don't run rtsold, but you aren't guaranteed not to
>>> have problems if you don't.  Best to let it run.
>>
>> I see the point but who on earth sent the initial router solicitation
>> on boot if I never enabled rtsold?
>>
>> I have not found rtsold in /etc/rc.d/netif or similar startup script.
>>
>> --
>> Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
>> 2:5005/49 at fidonet http://vas.tomsk.ru/
> 
> 
> The rtsol command will send a single router solicitation. It's probably
> getting invoked on startup. Or, you might've just gotten lucky and heard an
> unsolicited router advertisement.

Indeed, it's called from /etc/network.subr if rtsold is NOT enabled.