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Re: [MEXT] About the flow binding charter item

Hi Marcelo,

Sorry for the late input due to vacation (yes, we have some vacation also in US :-)

> -----Original Message-----
> From: mext-bounces at ietf.org [mailto:mext-bounces at ietf.org] On Behalf Of
> marcelo bagnulo braun
> Sent: Wednesday, May 20, 2009 6:05 AM
> To: mext
> Cc: Jari Arkko; Julien Laganier
> Subject: [MEXT] About the flow binding charter item
> 
> Hi,
> 
> There seems to be some discrepancies about the MEXT charter item
> regarding the work on flow bindings.
> Since the charter is the guide for our work, it would be important to
> clarify it, so we can have a unified interpretation of the charter.
> Please note that what it is in the charter is not cast in stone, but
> it seems to reflect previous consensus and we need good reasons to
> change it.
> 
> So, the current charter item about flow bindings reads:
> 
> - A "Flow/binding policies exchange" solution for an exchange of
> policies from the mobile host/router to the Home Agent and from the
> Home Agent to the mobile host/router influencing the choice of the
> Care-of Address and Home Agent address. The solution involves two
> specifications, one for the policy format and another for its
> transport [both Standard Track].
> 
> The first problem with this text is the use and interpretation of the
> word policy. Since the policy word may have a broad interpretation.
> it would be important to make the charter more explicit about the
> expected work. We understand that it is the WG consensus that what
> need to be exchanged is a solution for the exchange of flow binding
> rules.
> 
> So, we understand that it would be more explicit to replace the usage
> of the expression Flow/binding policies exchange by Flow Binding
> rules exchange. Would that reflect with the WG interpretation?
> 
> Second, the current charter item explicitly mentions that the
> proposed approach must support sending flow binding information from
> the MN to the HA and also from the HA to the MN. Moreover, the
> current charter talks about influencing not only the selection of the
> CoA but also the selection of the HA address. However, our current WG
> document does not supports sending information from the HA and it
> does not cover the possibility of influencing the HA address. So, one
> possible interpretation of the charter would be that the MN sends
> flow binding information to influence the CoA selection and the HA
> sends flow binding information to influence the HA address selection.
> Other interpretation is that both the MN and the HA send information
> regarding both the HA address and the CoA selection.
> 
> So, we would like that the WG express their opinion on both items
> mentioned above:
> 
> 1- whether we should replace Flow/binding policies exchange by Flow
> Binding rules exchange in the charter
> 

Agree

> 2- whether the information should be sent from the MN to the HA only
> or it should also be sent from the HA to the MN and if the
> information exchanged in each direction should affect the CoA and/or
> the HA address.
> 

From a protocol point of view it would be easy to allow both but from an architectural point of view we need to understand if that makes sense. As already commented there is no other entity in the picture which knows about the current application running in the terminal, the accesses available to the terminal and their status and characteristics, the resources available to the terminal than the terminal itself. The HA cannot know any of those elements which are needed to make a consistent flow routing decision. For this reason I think it should be unidirectional from the MN to HA.

What the network can provide are pseudo-static information about how to use different accesses when they are available based on the environment. This kind of information is usually provided as configuration information and should not be carried over Mobile IP (e.g. OMA-DM is a more suitable protocol to configure such kind of policies in the terminal)

Thanks
Gerardo 

> Regards, Julien and marcelo
> 
> 
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