Subject: [Mip6] AD review of draft-ietf-mip6-bootstrapping-integrated-dhc

From: Jari Arkko <[email-masked]>
Date: Mon, 11 Jun 2007 14:19:29 +0300

Hi all,

I have made my AD review on this document. It is generally
in good shape, but I would like to raise the following two
issues:

1. The document assumes that there is communication between
    the NAS and the DHCP server/relay parts in the visited
    network. From what I can see, such communication is
    only needed, however, if the assigned home agent information
    is going to differ between mobile nodes in a certain
    way. Specifically, if the assignment decision depends on
    local criteria (load in different home agents, round-robin
    status) and policy that does not differ between AAAHs
    or mobile nodes, then no such communication is needed.

    Not having to assume co-location or communication
    would simplify the implementation of this considerably.
    This would also cover one important use case that I
    can see, an access network that offers local home
    agents without any specific additional agreements
    or roaming services.

    Has such a case been considered in the discussion?
    Is it feasible to allow devices to implement
    such a simplified mode of operation?

2. A review in DHC WG needs to happen to ensure that
    the planned model is in line with what the DHCP experts
    feel is achievable. I will ask the chairs to arrange this
    before we go to IETF Last Call.

Jari

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From: "Chowdhury, Kuntal" <[email-masked]>
Date: Mon, 11 Jun 2007 12:38:54 -0400

Hello Jari,

Thanks for reviewing the document. Please see my comments inline....

BR,
Kuntal

> -----Original Message-----
> From: Jari Arkko [mailto:[email-masked]]
> Sent: Monday, June 11, 2007 6:19 AM
> To: [email-masked]
> Cc: Mobile IPv6 Mailing List
> Subject: AD review of draft-ietf-mip6-bootstrapping-integrated-dhc
> 
> 
> Hi all,
> 
[KC>] Home Agent assignment in the local network is covered in section
4.2.2 (Home Agent allocation in the ASP). In this scenario, the Home
Agent is assigned by the DHCP server in the local network. The HA
assignment policy in the ASP can be based on the criteria that you
mentioned (HA load status, round robin etc.) in the DHCP server. The
criteria that AAAH uses to pick a HA can be different and independent of
the same in DHCP server.

Regarding NAS - DHCP relay communication: if we assume that there is no
communication between these two functions, conveyance of the received
information from the AAAH to the DHCP system will be an issue.

>     agents without any specific additional agreements
[KC>] I agree with you that if collocation assumption of NAS and DHCP
relay can be removed, the solution will become simpler. However, the
assignment of the HA in the home MSP (other than the ASP) will be
unresolved in that case. May be we can clarify this by adding a
statement like this: if assignment of home agent in the home MSP is not
required by a deployment, collocation of NAS and the DHCP relay
functions won't be necessary. In such a case, implementation of the
options and procedures defined in [HIOPT] should suffice.

>     such a simplified mode of operation?
[KC>] Simple [HIOPT] based bootstrapping of the local home agent address
is feasible. It was discussed at the time of developing this solution.
May be in the current I-D we should explicitly mention about the simpler
mode of operation.

>     before we go to IETF Last Call.
[KC>] That will be good.

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From: "Vijay Devarapalli" <[email-masked]>
Date: Mon, 11 Jun 2007 11:31:01 -0700

Jari, 

>     or mobile nodes, then no such communication is needed.

The main focus of this document is to be able to assign home agents
from different MSPs dynamically. The NAS should be able to dynamically
figure out which MSP to contact (based on the MN's identity) and fetch
the home agent information, and deliver that information to the mobile
node. The assigned home agent information could even vary between two 
mobile nodes that belong to the same MSP.

Assigning home agents from the local network is an "add-on" feature.

So the NAS - DHCP server/relay communication is very important.

>     such a simplified mode of operation?

Yes, this is possible. But we have to consider whether the mobile
node necessarily wants this service from the visited network. 
And it should be possible for the mobile node and the home agent
in the visited network to be able to authenticate each other for
sending binding updates. 

Vijay

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From: Jari Arkko <[email-masked]>
Date: Mon, 11 Jun 2007 21:41:56 +0300

Vijay,

> in the visited network to be able to authenticate each other for

Sure. But I don't see the problem in achieving that, even if the
home agents are statically assigned in the local network. If
the access authentication can be performed somehow, the
mobility authentication should be possible too, e.g.,
with the same credentials and using IKEv2 EAP mode.

Jari

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From: "Vijay Devarapalli" <[email-masked]>
Date: Mon, 11 Jun 2007 11:48:07 -0700

> with the same credentials and using IKEv2 EAP mode.

Right. But you had said something about "... without any specific
additional agreements or roaming services." There is no issue, 
protocol-wise, it is more of a deployment issue. 

Vijay

---

From: Jari Arkko <[email-masked]>
Date: Tue, 12 Jun 2007 16:12:34 +0300

Vijay,

> protocol-wise, it is more of a deployment issue. 

Ah, sorry. You are right. I'm fine with this as long as we
explain the issue in the document.

Jari