Subject: Re: [MOBILE-IP] MIPv6 address conflict checking?

From: Thomas Eklund <[email-masked]>
Date: Mon, 13 Dec 1999 10:10:30 +0100

> -----Original Message-----
> From: Francis Dupont [mailto:[email-masked]]
> Sent: Saturday, December 11, 1999 5:56 PM
> To: [email-masked]
> Subject: Re: [MOBILE-IP] MIPv6 address conflict checking?
>
>
>  In your previous mail you wrote:
>
>    What about the case when you get an indication from the
> lower layer,
>    e.g., if your wavelan driver notifies that you have
> changed access point?
>
> => my WaveLAN doesn't notify this... If you have a reliable indication
> from the lower layer you MAY do a DAD. There is a thread about what
> to do in such a case in the IPng mailing list.

You can add filters to your move detection algorithm and base the filtering
on the field strength for instead. Then you must advertise you router prefix
in every radio cell so basically you get a new CoA from every AP, but a
better approach would be to have a couple of AP connected to a router that
would announce the same subnet. So basically you have local L2 handover and
when you move from the area that the router cover you do a handover in
mobileipv6.

Basically you must be able to handle several active CoA binding and only
have one active at the time and base it on several policy decision like
network load, field strength, operator etc.

/Thomas Eklund
>
>    > Then the speed of handover is not an issue for me.
>
>    I agree that link layer mechanisms is preferred if you want a fast
>    handover, but that requires the access points to be on the same
>    IPv6 subnet?
>
> => yes and access points should be interconnected with a LAN
> (WaveLAN access points are in fact an Ethernet + two WaveLANs bridge
> and can/should be used this way).
>
>    If you also want to provide IPv6 multicast, you will probably want
>    to limit the number of access points per subnet.
>
> => you can limit multicast traffic using MLD spoofing (as we do
> for IPv4 multicast with IGMP spoofing).
>
> [email-masked]
>

---

From: Francis Dupont <[email-masked]>
Date: Mon, 13 Dec 1999 11:07:25 +0100

You can add filters to your move detection algorithm and base the filtering
   on the field strength for instead.

=> this doesn't give a reliable L3 movement detection (ie. it is a typical
L2 trick).

   Then you must advertise you router prefix in every radio cell so
   basically you get a new CoA from every AP,

=> same concern.

   but a better approach would be to have a couple of AP connected to
   a router that would announce the same subnet. So basically you have
   local L2 handover and when you move from the area that the router
   cover you do a handover in mobileipv6.

=> I agree, on cellular radio links we need both L2 and L3 mechanisms.
My concern is about to use L3 mechanisms when obviously a L2 one is
far better suit for.

=> you can have only one active CoA home registration (ie. today the home
agent deals only with one CoA) then I believe you'd like to play with
correspondent bindings, ie. be able to handle a different CoA per
correspondent? (this is not the 10.9 idea which is for in transit
packets for a previous CoA)

[email-masked]

PS: I think IPv6 movement detection should be based on prefixes announced
by router advertisements as described in Solomon's book page 259 but
there should be a protection against configuration errors where a router
annonces a set of random prefixes (ie. the mobile should send some router
solicitations in order to get more informations: the whole set of prefixes,
more routers, ... it can be a good idea to do DAD at the same time).