Re: [MEXT] Removing bindings for IPv4 only - please comment

[<[e-mail]>]

I understood the text as a useful clarification.  I understood it
this way.  When a mobile node moves to an IPv6 foreign network,
and there obtains the v6CoA address, it sends a binding update

    BU
        src = v6CoA
        Destination Option with v6HoA
        lifetime > 0
        Alternate Care-of Address v6CoA
        IPv4 Home Address v4HoA

to the home agent, and the home agent will in its binding cache insert
two entries

    (1) v6HoA -> v6CoA
    (2) v4HoA -> v6CoA

The clarification to me was then, that the mobile node, while at this
foreign IPv6 network, could ask the home agent to remove both of the
bindings by sending

    BU
        src = v6CoA
        Destination Option with v6HoA
        lifetime = 0

or could ask the home agent to remove the IPv4 binding (retaining
the IPv6 binding) by sending

    BU
        src = v6CoA
        Destination Option with v6HoA
        lifetime > 0
        Alternate Care-of Address v6CoA

I'll go back to the situation where the binding cache has entries (1)
and (2).  If the mobile node moves to an IPv6-only link where it gets 
only the v6HoA address, and wants to continue using v4HoA, then the
home agent's binding cache should be provided with the entry

    (a)  v4HoA -> v6HoA

Or the other situation, the mobile node moves to an IPv4-only link 
getting only v4HoA, the binding cache should be provided with the entry

    (b)  v6HoA -> v4HoA

Maybe you could help me sorting out: what is the contents of
the binding updates to be sent to the home agent in the two
situations?  And are both situations covered with the DSMIP
specification?

Christian
 

> -----Original Message-----
> From: Hesham Soliman [mailto:[e-mail]] 
> Sent: 12. december 2008 13:37
> To: Kaas-Petersen Christian; [e-mail]
> Cc: [e-mail]; [e-mail]
> Subject: Re: [MEXT] Removing bindings for IPv4 only - please comment
> 
> 
> > Fine with the addition.  The original suggestion of Karen, now 
> > described in draft-premec-mext-extended-home-link, is something 
> > different, namely maintaining both IPv4 and IPv6 home 
> addresses on a 
> > home link which gives native support for either IPv4 or IPv6.
> > Suppose the home link supports only IPv4.  The home agent 
> will remove 
> > the entry for the v4HoA address, retaining the entry for the v6HoA, 
> > and this entry will indicate packets for v6HoA will have to be 
> > IP-in-IP tunneled to v4HoA.
> 
> => Right, but this is what the text I sent does. It removes 
> the v4 binding and keeps the IPv6 binding. If the link is 
> IPv4 only then it will bind the
> v6 HoA to that IPv4 address.
> 
> Hesham
> 
> > 
> > Christian
> > 
> >> -----Original Message-----
> >> From: [e-mail] [mailto:[e-mail]] 
> On Behalf 
> >> Of Hesham Soliman
> >> Sent: 12. december 2008 07:28
> >> To: [e-mail]
> >> Cc: Jari Arkko; Julien Laganier
> >> Subject: [MEXT] Removing bindings for IPv4 only - please comment
> >> 
> >> Hi all,
> >> 
> >> Gerardo requested that we consider the issue of removing 
> an IPv4-only 
> >> bindings in the spec. We discussed this with the chairs 
> and it seemed 
> >> like a simple add-on to the spec. I'm still wondering if 
> this is the 
> >> same thing that Karen asked for earlier and we decided to do it 
> >> separately. If it is, then I don't understand why we 
> didn't consider 
> >> the following solution (can't remember if I suggested it before).
> >> 
> >> I've added the following text to the draft, please let me 
> know if you 
> >> have any comments ASAP. I want to submit this version on 
> the weekend 
> >> if possible.
> >> All the IESG comments have been included. It's pretty straight 
> >> forward and follows standard MIPv6 logic.
> >> 
> >> <section title="Removing Bindings">
> >>                 
> >> <t>Mobile nodes will remove bindings from the home agent's binding 
> >> cache whenever they move to the home link, or simply when mobility 
> >> support is not needed.</t>
> >> 
> >> <t>De-registering the IPv6 home address is described in <xref 
> >> target="RFC3775"/>. The same mechanism applies in this 
> specification. 
> >> Mobile nodes may remove the binding for the
> >> IPv4 home address only, by sending a binding update that does not 
> >> include the IPv4 home address option. Upon receiving this binding 
> >> update, the home agent will replace the existing cache 
> entries with 
> >> the content of the new message. This ensures that the
> >> IPv4 home address binding is removed, while maintining an
> >> IPv6 binding.</t>
> >> 
> >> <t>Note that the mobile node cannot remove the IPv6 home address 
> >> binding while maintaining an IPv4 home address binding.</t>
> >>                 
> >> <t>A binding update message with a lifetime of zero, will 
> remove all 
> >> bindings for the mobile node.</t> </section>
> >> 
> >> Hesham
> >> 
> >> 
> >> _______________________________________________
> >> MEXT mailing list
> >> [e-mail]
> >> https://www.ietf.org/mailman/listinfo/mext
> >> 
> 
> 
> 
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