Subject: Re: [MOBILE-IP] A practical question...

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Wed, 11 Oct 2000 01:26:02 +1100

Hi Thierry,

Thanks for the quick reply
Please see my comments below.

Cheers,
Hesham

> > I believe your solution is perfect for one case :
> > The devices connected to the MR do not have a MIPv6 implementation.
> > Some people might argue that if you do not have a MIPv6 implementation
> > then you should not be mobile. But that is also debatable I think.
>
> > If the devices have MIPv6 in them (ie. MN's) then they can manage
> > their
> > own mobility. There is a chapter on this in the HMIPv6 draft. In this
> > case
> > the MR advertises itself as a MAP upon entering a foreign network.
> > As a result the MN's attached to it would register with the HA with an
> > alt-CoA which is the MR's (MAP) address.
> >
> > It would be good to get your comments on this solution.
>
> As I understand your draft
> http://ietf.org/internet-drafts/draft-ietf-mobileip-hmipv6-00.txt, the
> MN enters the mobile network and listens to router advertisements.   It
> gets a LCOA and registers with the MAP, i.e the mobile router MR.   It
> adversites the MAP's address to its HA and its CNs.   Fine.
>
        No it doesn't need to get an on link CoA, it keeps the same address,
        ie Home address. The MR (MAP) get a new CoA (topologially correct).
        It registers with the HA. The MNs attached to the MR (MAP) register
        the MAP's address as an alt-CoA with the HA. All packets destined
        to the MNs get routed by the CNs to the MAP which then routes them
        to the MN's on link.

> How packets get routed from the CN to the MN ?  I understand that the
> MAP's address is the home address of the MR.    The MR also gets a
> care-of address at each of its Access Router.    Then, the packets sent
> from CN to MN is sent to the MAP's address and the routing header
> contains the home address of the MN. The packet gets routed to the HA
> of the MR where it is encapulated to the current care-of address of the
> MR as if the final destination was the MR itself.   The final
> destination is transparent to the HA.   The packet is received and
> decapsulated by MR and the desitnation address is switched with the one
> contained in the routing header.  The packet is then forwarded to the
> MN.
>
> Your proposition therefore works for mobile nodes MNs visiting a mobile
> network.  (However, there is no optimal routing between CN and MN, but
> this not the present subject of the discussion)
>
        What do you mean by an optimal route between the CN and MN ?
        Route optimisation is used in this case. Is there a more optimal
route ?

> What about FIXED nodes located in the mobile network ?  This was the
> topic of my draft
> http://www.inrialpes.fr/planete/people/ernst/Documents/draft-ernst-mobilei
> p-v6-network.
> For the same reasons as outlined in my draft, the packet sent from a CN
> to a FIXED host located in the mobile network can not reach its final
> destination.   Packets are routed to the HA of the MR and then the HA
> does not know what to do with them.  Those enters in a loop until the
> TTL expires.   See the explanation in my draft.  As a result, FIXED
> nodes in the mobile network never see the packets sent from CNs. From
> what I understand, your solution does address this issue.
>
        I'll read your draft again, but I don't know what you mean by a
FIXED host ?

> I agree that your solution is fine for MNs that visit the mobile
> network, but one shouldn't forget about those FIXED host located in the
> mobile network.  To me, the issue of routing packet from CNs to the
> FIXED host is more important as this is more likely to happen.
>
> Cheers,
> Thierry.
>
> * mailto:[email-masked]  Tel +33 (0) 4 76 61 52 69
> * INRIA Rhone-Alpes Projet PLANETE       (fax 52 52)
> * http://www.inrialpes.fr/planete/people/ernst/Welcome.html

---

From: Thierry Ernst <[email-masked]>
Date: Tue, 10 Oct 2000 16:59:11 +0200

Hi Hesham,

Thank you for your precisions.

>      route

What care-of address contains the BU sent by the MN to its CNs ?   It
contains the MR 's address, right ?  But the MR is also a mobile node,
then the MR's address is in fact a home address.   Packets from the CN
to the MN therefore get routed to the MR's HA.   There is no true route
optimisation.   It is true that packets do not transit by the MN's HA,
otherwise you would end up  in a double redirection.

>      I'll read your draft again, but I don't know what you mean by a

A mobile network is not only a router, but a mobile router and all its
attached nodes.  Those attached nodes are FIXED relative to the MR.
The Mobile Network might even be composed of several routers (i.e. a set
of subnetworks).

A Mobile Node is a node that is visiting the mobile network by
opposition to the FIXED nodes that always remain located in the mobile
network (let's call them Mobile Network Nodes - nodes from the mobile
network - MNNs).

 Cheers,
 Thierry.