Re: Questions on IPv6 stateless autoconfiguration
Hello,
Michael Richardson a écrit :
> Jan Lühr <ff@jluehr.de> wrote:
>
> > Assuming, that R1, R2 announce global prefixes:
> > Are both of them installed in A's routing table as default routers
> > using their link local address?
I have not tested, but I guess so.
WARNING : SLAAC may have unpredictable effects with multihoming (just
like DHCP).
> > can radvd be configured to
> > provide stateless auto configuration for global prefixes without being
> > considered as a default router?
Yes. Set AdvDefaultLifetime to 0 in radvd.conf for that router.
See man radvd.conf.
> > Does it change when using ULA addresses?
No. ULAs are just another globally unique prefix.
> > What happens, if A fires up a web browser trying to reach
> > http://ipv6.google.com. Afaik A's sender address is chosen randomly,
> > using either R1's or R2's network.
Not randomly. The default source address depends on the chosen route.
> > Is the corresponding router used,
The other way around. By default : select route, then select source address.
> > accordingly - or - may it occur, that R1 is used in conjunction with an
> > IPv6 address from R2's network?
Yes, when you force the source address regardless of the route. A
sending process can select the source address, not the route.
> If later: How can I force A to use the corresponding router?
>
> It ought to be configured this way by default, but you need policy based
> routing using "ip rule from.. table ..."
I would strongly advise not to mix policy routing with SLAAC.
> > Assuming, R1 crashes. Does A detect this? Is R1's default route removed
> > from the routing table, then?
>
> Yes... the route becomes unreachable
But that won't make the host use the other route.
> and expires.
But it may take a long time, depending on the AdvDefaultLifetime sent by
the router and the last time an RA was received.
> > Assuming, that R1 is a wifi hotspot router, and R2 a vpn endpoint
> > (OpenVPN, tap, tls-server).
> -> How can I force the client to use the VPN whenever possible, while
> > using the hotspot network for reaching the VPN-endpoint while using the
> > sender addresses accordingly?
Don't use SLAAC for the VPN. If you cannot avoid it, set
AdvDefaultPreference to high in radvd.conf for the VPN router, in hope
that the hotspot router has a lower value.
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