MCoA Issue: Simultaneous Usage of Home and Away interfaces

Hi!

I had posted an email to the Monami6 mailing list proposing
the adoption
of Section 7 of draft-wakikawa-mip6-no-ndp-00 as a working
solution to
resolve the issue of simultaneous usage of home and away
interfaces.

See:-
 http://www1.ietf.org/mail-archive/web/monami6
/current/msg01051.html

A month has passed and there has been no negative responses.
Some small
amount of support has also been expressed.  As such, I'm
submitting the
following suggested changes to
draft-ietf-monami6-multiplecoa-02.txt for
discussion and action.  The actual text has been heavily
plagiarized
from draft-wakikawa-mip6-no-ndp-00.txt. (Apologies to
authors)    

Changes:-

3.3.  Returning Home
"
   In the above two cases, a mobile node cannot use
interfaces attached
   to both home and foreign links simultaneously.
<cut>
   If this is what a
   mobile node wants, a home agent can set up another link
other than
   home link and uses the link for the mobile node to return
virtually
   to home network.  Even though packets from and to the
mobile node are
   routed via the home agent, the hop count is kept in one. 
The
   overhead should be negligible since it is only for an
additional IPv6
   header and processing tunnel (encapsulation and
decapsulation) per
   packets.  The detail can be found in Figure 7
</cut>

<paste>
   This restriction is
   related to the Proxy NDP operation on a Home Agent.  The
Home Agent
   needs to defend a mobile node's home address by the proxy
NDP for
   packet interception, while the mobile node defends its
home address
   by regular NDP to send and receive packets at the
interface attached
   to the home link.  Two nodes, Home Agent and Mobile Node,
compete ND
   state.  This will causes address duplication problem at
the end.

   This document recommends not to use the Proxy NDP for
this scenario.
   When one of the Mobile Node's interface is attached to
the home link
   and the other is attached to the foreign link and it
decides to
   utilize both interfaces, it notifies the Home Agent using
the H flag
   which means the Mobile Node is attached to the home link.
If the
   proxy NDP is disabled, the main problem can be solved. 
In the
   Multiple Care-of Address Registration case, the
elimination of Proxy
   NDP enable that Mobile Node and Home Agent maintain
multiple
   bindings, one of the Mobile Node's interface is attached
to the home
   link and the other is attached to the foreign link.
</paste>
"

4.2.1.  Binding Unique Identifier sub-option
"
<replace>
                      1                   2                 
 3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
6 7 8 9 0 1
                                      
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                       |   Type = TBD  |    
Length    |
      
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
+-+-+
       |     Binding Unique ID (BID)  
|Priority/Status|C|H|Reserv
ed |
      
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+---------------------------
----+
       +                                                    
          +
       +                    care-of address (CoA)           
          +
       +                                                    
          +
      
+-----------------------------------------------------------
----+
</replace>

<paste>
   Home Binding (H) flag
      When this flag is set, a home agent stores a Home
Address in the
      Care-of Address field of the binding cache entry. 
This flag must
      be used only for binding de-registration.  This flag
is not used
      in the bulk registration mode.
</paste>

   Reserved

<replace>
      5 bits Reserved field.  Reserved field must be set
with all 0.
</replace>
"

5.6.  Returning Home
"
   no longer receives packets at the interface attached to
the home
   link.  All packets are routed to other interfaces
attached to a
   foreign link.

<paste>
   Alternatively, the Mobile Node may choose to activate
both the
   interfaces attached to the home link and the foreign
link, and
   communicates with all of the interfaces.  The Mobile Node
notifies
   the Home Agent using the H flag which means the Mobile
Node is
   attached to the home link. The Home Agent then no longer
   uses Proxy Neighbor Advertisement to intercept packets
and the Mobile
   Node can utilize both of interfaces attached to the home
link and the
   foreign link simultaneously.  The Home Agent can
intercept packets by
   IP routing, but not by proxy Neighbor Discovery.

   When the Mobile Node returns home, it de-registers a
binding for the
   interface.  While the bindings for the interfaces
attached to the
   foreign link are still active.  Intercepting packets, the
Home Agent
   can decide whether it tunnels to the foreign interface or
routes to
   the home interface of the Mobile Node.  To do so, the
Home Agent must
   know that the Mobile Node is back to the home link. 
However, if the
   binding is deleted according to [2], there is no way for
the Home
   Agent to know that the Mobile Node is at the home, too. 
The Home
   Agent SHOULD invalidate the binding for the interface
attached to the
   home link and MAY NOT delete it.  It can alternatively
mark that the
   Mobile Node is at the home link, too.  As an
   example, the Home Agent inserts the Home Address of the
Mobile Node
   in the Care-of Address field of the Mobile Node.  The
binding is
   named "Home Binding" in this doc.  The Home
Agent MAY manage this
   home binding as same as the other binding entry in terms
of lifetime
   validation, etc.  The Mobile Node MAY send multiple
binding de-
   registration to keep this home binding active. 
Alternatively, the
   Home Agent can use infinity lifetime for the lifetime of
the home
   binding.  When the Mobile Node leaves the Home Link, it
can update
   the home binding to the normal binding.  Before that, the
Home Agent
   believes the Mobile Node is at the home and may route
packets for the
   Mobile Node to the Home Link.
</paste>
"

6.3.  Processing Binding Update
"
   o  If the Lifetime field of the Binding Update is zero,
the receiver
      node deletes the binding entry which BID is same as
BID sent by
      the Binding Unique Identifier sub-option.  If the
receiver node
      does not have appropriate binding which BID is matched
with the
      Binding Update, it MUST reject this de-registration
Binding
      Update.  If the receiver is a Home Agent, it SHOULD
also return a
      Binding Acknowledgment to the mobile node, in which
the Status
      field is set to [not Home Agent for this mobile node,
133].  If O
      flag is set in the deregistering Binding Update, the
receiver can
      ignore this flag for deregistration.
<paste>
      If the H flag is set, the home agent stores a Home
Address in the
      Care-of Address field of the binding cache entry.  The
home agent
      no longer performs proxy NDP for this mobile node
until this
      entry is deleted.
</paste>
"

Appendix A.  Example Configurations
"
<cut>
   Figure 7 depicts the scenario where interfaces of MN are
attached to
   the foreign links.  One of foreign link is managed by the
home agent.
   The HA and CN have the binding entries listed in Figure 7
in their
   binding cache database.  The home agent advertises a
prefix which is
   other than home prefix.  The mobile node will generate a
care-of
   address from the prefix and registers it to the home
agent.  Even if
   the mobile node attaches to a foreign link, the link is
managed by
   its home agent.  It will tunnel the packets to the home
agent, but
   the home agent is one-hop neighbor.  The cost of tunnel
is
   negligible.  If the mobile node wants to utilize not only
an
   interface attached to home but also interfaces attached
to foreign
   link, it can use this foreign link of the home agent to
return a one
   hop foreign link on behalf of a home link.  This is
different from
   the general returning home, but this enable the
capability of using
   interfaces attached to both home and foreign link without
any
   modifications to Mobile IPv6 and NEMO basic support.

                    +----+
                    | CN |
                    +--+-+
                       |
                   +---+------+          +----+
            +------+ Internet |----------+ HA |
            |      +----+-----+          ++-+-+
        CoA2|           |                 | |   Home Link
         +--+--+        |             ----|-+------
         |  MN +========+                 |
         +--+--+ CoA1                ---+-+------
       CoA3 |                           |  Foreign Link
            +---------------------------+

     Binding Cache Database:
        home agent's binding (Proxy neighbor advertisement
is active)
              binding [a:b:c:d::EUI  care-of address1 
BID1]
              binding [a:b:c:d::EUI  care-of address2 
BID2]
              binding [a:b:c:d::EUI  care-of address3 
BID3]
        correspondent node's binding
              binding [a:b:c:d::EUI  care-of address1 
BID1]
              binding [a:b:c:d::EUI  care-of address2 
BID2]
              binding [a:b:c:d::EUI  care-of address3 
BID3]


    Figure 7: Emulating to Utilize Interfaces Attached to
both Home and
                               Foreign Links
</cut>
"

Regards,
Ben


-- 


/<<<<<<<<<<<<<<<
;<<<<<++>>>>>>>>>&
gt;>>>>>>>>>>
| Benjamin Koh Tien-Ming                   |
| R & D Engineer                           |
| Panasonic Singapore Laboratories Pte Ltd |
| Tel: (65)6550 5481 Fax: (65)6550 5459    |
| E-mail: benjamin.kohtmsg.panasonic.com  |
>>>>>>>>>>>>>>>
;>>>>>--<<<<<<<<<&
lt;<<<<<<<<<</


_______________________________________________
Monami6 mailing list
Monami6ietf.org
https:
//www1.ietf.org/mailman/listinfo/monami6

Hi All,

Thanks for Benjamin.
I am revising the MCoA draft for the IETF Chicago now.
It looks there is no objection on this changes, i plan to
include  
this option.

regards,
ryuji



On 2007/06/14, at 21:57, Benjamin Koh Tien-Ming wrote:

> Hi!
>
> I had posted an email to the Monami6 mailing list
proposing the  
> adoption
> of Section 7 of draft-wakikawa-mip6-no-ndp-00 as a
working solution to
> resolve the issue of simultaneous usage of home and
away interfaces.
>
> See:-
>  http://www1.ietf.org/mail-archive/web/monami6
/current/msg01051.html
>
> A month has passed and there has been no negative
responses. Some  
> small
> amount of support has also been expressed.  As such,
I'm submitting  
> the
> following suggested changes to draft-ietf-monami6- 
> multiplecoa-02.txt for
> discussion and action.  The actual text has been
heavily plagiarized
> from draft-wakikawa-mip6-no-ndp-00.txt. (Apologies to
authors)    
>
> Changes:-
>
> 3.3.  Returning Home
> "
>    In the above two cases, a mobile node cannot use
interfaces  
> attached
>    to both home and foreign links simultaneously.
> <cut>
>    If this is what a
>    mobile node wants, a home agent can set up another
link other than
>    home link and uses the link for the mobile node to
return virtually
>    to home network.  Even though packets from and to
the mobile  
> node are
>    routed via the home agent, the hop count is kept in
one.  The
>    overhead should be negligible since it is only for
an additional  
> IPv6
>    header and processing tunnel (encapsulation and
decapsulation) per
>    packets.  The detail can be found in Figure 7
> </cut>
>
> <paste>
>    This restriction is
>    related to the Proxy NDP operation on a Home Agent. 
The Home Agent
>    needs to defend a mobile node's home address by the
proxy NDP for
>    packet interception, while the mobile node defends
its home address
>    by regular NDP to send and receive packets at the
interface  
> attached
>    to the home link.  Two nodes, Home Agent and Mobile
Node,  
> compete ND
>    state.  This will causes address duplication problem
at the end.
>
>    This document recommends not to use the Proxy NDP
for this  
> scenario.
>    When one of the Mobile Node's interface is attached
to the home  
> link
>    and the other is attached to the foreign link and it
decides to
>    utilize both interfaces, it notifies the Home Agent
using the H  
> flag
>    which means the Mobile Node is attached to the home
link. If the
>    proxy NDP is disabled, the main problem can be
solved.  In the
>    Multiple Care-of Address Registration case, the
elimination of  
> Proxy
>    NDP enable that Mobile Node and Home Agent maintain
multiple
>    bindings, one of the Mobile Node's interface is
attached to the  
> home
>    link and the other is attached to the foreign link.
> </paste>
> "
>
> 4.2.1.  Binding Unique Identifier sub-option
> "
> <replace>
>                       1                   2            
      3
>         0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
4 5 6 7 8 9  
> 0 1
>                                       
+-+-+-+-+-+-+-+-+-+-+-+-+-+- 
> +-+-+
>                                        |   Type = TBD 
|      
> Length    |
>       
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

> +-+-+
>        |     Binding Unique ID (BID)  
|Priority/Status|C|H| 
> Reserved |
>        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 
> +-------------------------------+
>         
> +                                                      
        +
>        +                    care-of address  
> (CoA)                      +
>         
> +                                                      
        +
>         
>
+-----------------------------------------------------------
----+
> </replace>
>
> <paste>
>    Home Binding (H) flag
>       When this flag is set, a home agent stores a Home
Address in the
>       Care-of Address field of the binding cache entry.
 This flag  
> must
>       be used only for binding de-registration.  This
flag is not used
>       in the bulk registration mode.
> </paste>
>
>    Reserved
>
> <replace>
>       5 bits Reserved field.  Reserved field must be
set with all 0.
> </replace>
> "
>
> 5.6.  Returning Home
> "
>    no longer receives packets at the interface attached
to the home
>    link.  All packets are routed to other interfaces
attached to a
>    foreign link.
>
> <paste>
>    Alternatively, the Mobile Node may choose to
activate both the
>    interfaces attached to the home link and the foreign
link, and
>    communicates with all of the interfaces.  The Mobile
Node notifies
>    the Home Agent using the H flag which means the
Mobile Node is
>    attached to the home link. The Home Agent then no
longer
>    uses Proxy Neighbor Advertisement to intercept
packets and the  
> Mobile
>    Node can utilize both of interfaces attached to the
home link  
> and the
>    foreign link simultaneously.  The Home Agent can
intercept  
> packets by
>    IP routing, but not by proxy Neighbor Discovery.
>
>    When the Mobile Node returns home, it de-registers a
binding for  
> the
>    interface.  While the bindings for the interfaces
attached to the
>    foreign link are still active.  Intercepting
packets, the Home  
> Agent
>    can decide whether it tunnels to the foreign
interface or routes to
>    the home interface of the Mobile Node.  To do so,
the Home Agent  
> must
>    know that the Mobile Node is back to the home link. 
However, if  
> the
>    binding is deleted according to [2], there is no way
for the Home
>    Agent to know that the Mobile Node is at the home,
too.  The Home
>    Agent SHOULD invalidate the binding for the
interface attached  
> to the
>    home link and MAY NOT delete it.  It can
alternatively mark that  
> the
>    Mobile Node is at the home link, too.  As an
>    example, the Home Agent inserts the Home Address of
the Mobile Node
>    in the Care-of Address field of the Mobile Node. 
The binding is
>    named "Home Binding" in this doc.  The
Home Agent MAY manage this
>    home binding as same as the other binding entry in
terms of  
> lifetime
>    validation, etc.  The Mobile Node MAY send multiple
binding de-
>    registration to keep this home binding active. 
Alternatively, the
>    Home Agent can use infinity lifetime for the
lifetime of the home
>    binding.  When the Mobile Node leaves the Home Link,
it can update
>    the home binding to the normal binding.  Before
that, the Home  
> Agent
>    believes the Mobile Node is at the home and may
route packets  
> for the
>    Mobile Node to the Home Link.
> </paste>
> "
>
> 6.3.  Processing Binding Update
> "
>    o  If the Lifetime field of the Binding Update is
zero, the  
> receiver
>       node deletes the binding entry which BID is same
as BID sent by
>       the Binding Unique Identifier sub-option.  If the
receiver node
>       does not have appropriate binding which BID is
matched with the
>       Binding Update, it MUST reject this
de-registration Binding
>       Update.  If the receiver is a Home Agent, it
SHOULD also  
> return a
>       Binding Acknowledgment to the mobile node, in
which the Status
>       field is set to [not Home Agent for this mobile
node, 133].   
> If O
>       flag is set in the deregistering Binding Update,
the receiver  
> can
>       ignore this flag for deregistration.
> <paste>
>       If the H flag is set, the home agent stores a
Home Address in  
> the
>       Care-of Address field of the binding cache entry.
 The home  
> agent
>       no longer performs proxy NDP for this mobile node
until this
>       entry is deleted.
> </paste>
> "
>
> Appendix A.  Example Configurations
> "
> <cut>
>    Figure 7 depicts the scenario where interfaces of MN
are  
> attached to
>    the foreign links.  One of foreign link is managed
by the home  
> agent.
>    The HA and CN have the binding entries listed in
Figure 7 in their
>    binding cache database.  The home agent advertises a
prefix  
> which is
>    other than home prefix.  The mobile node will
generate a care-of
>    address from the prefix and registers it to the home
agent.   
> Even if
>    the mobile node attaches to a foreign link, the link
is managed by
>    its home agent.  It will tunnel the packets to the
home agent, but
>    the home agent is one-hop neighbor.  The cost of
tunnel is
>    negligible.  If the mobile node wants to utilize not
only an
>    interface attached to home but also interfaces
attached to foreign
>    link, it can use this foreign link of the home agent
to return a  
> one
>    hop foreign link on behalf of a home link.  This is
different from
>    the general returning home, but this enable the
capability of using
>    interfaces attached to both home and foreign link
without any
>    modifications to Mobile IPv6 and NEMO basic
support.
>
>                     +----+
>                     | CN |
>                     +--+-+
>                        |
>                    +---+------+          +----+
>             +------+ Internet |----------+ HA |
>             |      +----+-----+          ++-+-+
>         CoA2|           |                 | |   Home
Link
>          +--+--+        |             ----|-+------
>          |  MN +========+                 |
>          +--+--+ CoA1                ---+-+------
>        CoA3 |                           |  Foreign
Link
>             +---------------------------+
>
>      Binding Cache Database:
>         home agent's binding (Proxy neighbor
advertisement is active)
>               binding [a:b:c:d::EUI  care-of address1 
BID1]
>               binding [a:b:c:d::EUI  care-of address2 
BID2]
>               binding [a:b:c:d::EUI  care-of address3 
BID3]
>         correspondent node's binding
>               binding [a:b:c:d::EUI  care-of address1 
BID1]
>               binding [a:b:c:d::EUI  care-of address2 
BID2]
>               binding [a:b:c:d::EUI  care-of address3 
BID3]
>
>
>     Figure 7: Emulating to Utilize Interfaces Attached
to both Home  
> and
>                                Foreign Links
> </cut>
> "
>
> Regards,
> Ben
>
>
> -- 
>
>
>
/<<<<<<<<<<<<<<<
;<<<<<++>>>>>>>>>&
gt;>>>>>>>>>>
> | Benjamin Koh Tien-Ming                   |
> | R & D Engineer                           |
> | Panasonic Singapore Laboratories Pte Ltd |
> | Tel: (65)6550 5481 Fax: (65)6550 5459    |
> | E-mail: benjamin.kohtmsg.panasonic.com  |
>
>>>>>>>>>>>>>>>
;>>>>>--<<<<<<<<<&
lt;<<<<<<<<<</
>
>
> _______________________________________________
> Monami6 mailing list
> Monami6ietf.org
> https:
//www1.ietf.org/mailman/listinfo/monami6


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