Subject: [Dime] dime-mip6-integrated and the type of home agent

From: Jouni Korhonen <[email-masked]>
Date: Wed, 18 Jun 2008 23:48:08 +0300

Hi all,

A proposal related to the MIP6-Agent-Info AVP. Currently
the AVP contains only the address information of the HA,
which is OK in the scope of the integrated scenario. However,
having a slight wider look at the possible uses for the
MIP6-Agent-Info AVP it might be beneficial to include an
AVP describing the "flavor" of the HA.  What I am proposing
is to add an enumerated MIP-Agent-Type AVP inside the group.

    <MIP6-Agent-Info> ::= < AVP Header: TBD >
                          [ MIP-Home-Agent-Address ]
                          [ MIP-Home-Agent-Host ]
                          [ MIP-Agent-Type ]
                        * [ AVP ]

The initial values would include:

MIP6_HA (0)
MIP6_LMA (1)
MIP6_DSMIP_HA (2)

As a side note.. this discussion has been gone through at least
once. At that time I thought using FQDN piggypack agent flavor
information would be enough.. but having a separate AVP would
actually be nicer imho.

Cheers,
	Jouni
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From: "Vijay Devarapallli" <[email-masked]>
Date: Wed, 18 Jun 2008 13:59:51 -0700

Hi Jouni,

What is the need to differentiate between a MIPv6 and DS-MIPv6 HA?
Since the DS-MIPv6 HA functionality includes MIPv6 HA, why would
someone deploy separate MIPv6 HA and DS-MIPv6 HA? If the discovered HA
does not support IPv4 Home Address assignment, the mobile node gets to
know about it anyway after the BU/BAck exchange.

> The initial values would include:

What is the MIPv6 HA and PMIPv6 LMA are co-located?

Its not clear to me what the above actually is trying to achieve. For
my benefit, can you please describe the scenario where such an
enumerated AVP would help? I could be missing something.

Vijay

---

From: Jouni Korhonen <[email-masked]>
Date: Thu, 19 Jun 2008 00:25:49 +0300

Hi Vijay,

> someone deploy separate MIPv6 HA and DS-MIPv6 HA? If the discovered HA

Nothing prevents anyone deploying plain MIP6 HA.

> know about it anyway after the BU/BAck exchange.

You could definitely do that in this way. What I was thinking is more  
like
that in DSMIP6 you can manage the IP4-HoA assignment via a  
subscription policy,
where as in MIP6 you just don't have that capability at all. It might be
better to be explicit here..?

Cheers,
	Jouni

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From: "Chowdhury, Kuntal" <[email-masked]>
Date: Thu, 19 Jun 2008 11:25:29 -0400

Jouni,

I agree with you that having an explicit AVP for this is better than
overloading some other parameter.

A few clarifications:

" MIP-Home-Agent-Host" - is this FQDN of the home agent?

If the Agent has more than one function, e.g. DSMIP6 HA and PMIP6 LMA,
how can we encode the type field? Should we encode it as bitmask?

-Kuntal

> -----Original Message-----
> From: Jouni Korhonen [mailto:[email-masked]]
> Sent: Wednesday, June 18, 2008 3:48 PM
> To: [email-masked]
> Cc: Julien Bournelle; Hannes Tschofenig; Chowdhury, Kuntal
> Subject: dime-mip6-integrated and the type of home agent
> 
> Hi all,
>

---

From: "Vijay Devarapallli" <[email-masked]>
Date: Thu, 19 Jun 2008 11:28:11 -0700

> overloading some other parameter.

I am not too comfortable with overloading the home agent AVP to tell
the MAG/Access router which mobility protocol to use for a particular
session. Why can't we define a separate AVP that tells the MAG/Access
router which mobility protocol is being used for an ongoing session
instead of the MAG/Access router figuring this out from the "type" of
the home agent?

Vijay

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From: "Chowdhury, Kuntal" <[email-masked]>
Date: Fri, 20 Jun 2008 12:48:31 -0400

Vijay,

Even if we define a new AVP for the protocol-type, we will have to
always group it with the home agent AVP. In that case, what is the
advantage of having a separate standalone AVP? 

-Kuntal

> From: Vijay Devarapallli [mailto:[email-masked]]
> Sent: Thursday, June 19, 2008 1:28 PM
> To: Chowdhury, Kuntal
> Cc: Jouni Korhonen; [email-masked]; Hannes Tschofenig
> Subject: Re: [Dime] dime-mip6-integrated and the type of home agent
>

---

From: "Vijay Devarapallli" <[email-masked]>
Date: Fri, 20 Jun 2008 11:38:30 -0700

> advantage of having a separate standalone AVP?

Don't you see the advantage? I think it makes sense not to overload
the home agent AVP. Rather we should define an explicit AVP that
indicates which mobility protocol (DS-MIPv6 or PMIPv6) is being used
for an on-going session. This can be sent along with the Home Agent
information (which would just contain the IP address of the home
agent/LMA).

Ideally, there shouldn't be a need for the MAG/Access router to be
told which mobility protocol to use. But never mind. :)

Vijay

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---

From: Jouni Korhonen <[email-masked]>
Date: Sat, 21 Jun 2008 20:14:50 +0300

Kuntal,

> " MIP-Home-Agent-Host" - is this FQDN of the home agent?

Contains the FQDN of the HA.. as well as the realm ;)

> how can we encode the type field? Should we encode it as bitmask?

You could have 1) multiple instances of MIP6-Agent-Info or 2)
use bitmask.. Latter could be more efficient. In case of bitmask
one could also dedicate a bit for local/home allocation information
as well (though the MIP-Home-Agent-Host already contains the
realm information for that purpose).

Cheers,
	Jouni

> "This email message and any attachments are confidential  
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---

From: <[email-masked]>
Date: Sun, 22 Jun 2008 22:58:02 +0200

Hi,

> know about it anyway after the BU/BAck exchange.

On a related issue, we should actually have two instances of
IP addresses. One for IPv6 and one for IPv4. I.e.:

    <MIP6-Agent-Info> ::= < AVP Header: TBD >
                        *2[ MIP-Home-Agent-Address ]
                          [ MIP-Home-Agent-Host ]
                          [ MIP-Agent-Type ]
                        * [ AVP ]

..as it is assumed that both DSMIP6 and PMIP6 will have deployments
that need the IPv4 address as well.

Cheers,
	Jouni

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From: "Vijay Devarapallli" <[email-masked]>
Date: Mon, 23 Jun 2008 10:59:17 -0700

Adding to what I wrote before...

3GPP kind of messed it up by having the PMIPv6 LMA, MIPv6 HA, DS-MIPv6
HA and MIPv4 HA all on the same network entity. Strictly speaking,
this extension (for figuring out what kind of mobility protocol is
being used for an on-going session) is only required for 3GPP. For
deployments that use only one type of mobility protocol, the MAG or
the access router would just need the IP address of LMA or the home
agent. They wouldn't need to know what kind of home agent it is.

So I think we should define the Home Agent AVP to just contain the IP
address or the FQDN and have a separate AVP (optional) that indicates
what kind of mobility protocol is being used for an on-going session.

Vijay

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From: "Vijay Devarapalli" <[email-masked]>
Date: Mon, 23 Jun 2008 11:08:48 -0700

Hi Jouni,

> that need the IPv4 address as well.

Agree.

Would the MAG or the access router have to know that they also need
the IPv4 address in addition to the IPv6 address and request for both?
Or will both addresses be returned, irrespective of what the MAG or
the access router asked for?

Vijay

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From: <[email-masked]>
Date: Tue, 24 Jun 2008 15:32:10 +0200

Vijay,

[snip]

> the access router asked for?

IMHO it would be simpler if both addresses are just returned, if
available
or allowed by the subscription policy. If capability exchange is really
needed, the MIP6-Feature-Vector could be used.

CHeers,
	Jouni