Subject: [netlmm] Comments on pmip6-ipv4-support

From: <[email-masked]>
Date: Wed, 2 May 2007 09:22:02 +0200

Hi,

I had a quick read on the pmip6-ipv4-support-00 draft (keeping in mind
that
this is -00 version). Good stuff! I got two initial comments.

The draft does not say much about private IPv4 addresses in user plane.
I think the draft should have text on how e.g. MAG, DHCP etc are
supposed
to  work when there are overlapping private IPv4 HoAs (as the DSMIP6
draft
allows those and operators are going to deploy those).

Also there is no mention of e.g. default gateway configuration when
describing
policy profile information and/or IPv4 HoA assignment from LMA. What
will be
provided e.g. by DHCP to the MN as the default GW? There isn't anything
about this in PBUs, right?

Cheers,
	Jouni

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---

From: "Sri Gundavelli" <[email-masked]>
Date: Wed, 2 May 2007 09:19:43 -0700

Hi Jouni,

Please see inline ..

-----Original Message-----
> From: [email-masked]
[mailto:[email-masked]] 
> Sent: Wednesday, May 02, 2007 12:22 AM
> To: [email-masked]
> Cc: [email-masked]; [email-masked]
> Subject: Comments on pmip6-ipv4-support

> allows those and operators are going to deploy those).

[Sri] There are two cases: 1) Allocation of private HoA addresses
and 2) Hosted LMA Model with overlapping private HoA addresses. 

For #1, the anchored mobiles at the MAG are from one operator and
so the addresses are not overloaded. This case is covered by DSMIP6
and as well in this draft.

For #2, its not covered in DSMIP6. The use case for this scenario is
not generic to MIP6 and so it wont be in DSMIP6. This document is a
result of a document split and the scope is exactly the same as
draft-sgundave-mip6-pmip6-02.txt. So, the overlapping scenario is not
in the scope of the base document.

However, the GRE use case was covered in some other draft, covering 
all the use cases.

http://www.ietf.org/internet-drafts/draft-muhanna-netlmm-grekey-option-00.tx
t

> about this in PBUs, right?

[Sri] Ryuji and me had lot of discussions on the default-gateway option.
We have added the option and later took it out from the draft. Since,
the support was for p2p link, the comment from some in the group was that
its not required. In any case, we decided to open this issue against
DSMIP6 and get a resolution there.  

The question, on a p2p link, is the mobile required to know the default
gateway address. How will the interface config look, if the LMA does
not provide this info, for the dynamic allocate case. So, this is an
issue/question for DSMIP6 and is not exclusive for PMIP6-IPv4 draft.

Thanks
Sri

---

From: <[email-masked]>
Date: Wed, 2 May 2007 23:08:26 +0200

Hi Sri,

Thanks for clarifications! See some more inline.

> > that this is -00 version). Good stuff! I got two initial comments.
> >
> > supposed to  work when there are overlapping private IPv4 
> HoAs (as the 
> > DSMIP6 draft allows those and operators are going to deploy those).
> 
> 
> [Sri] There are two cases: 1) Allocation of private HoA 
> addresses and 2) Hosted LMA Model with overlapping private 
> HoA addresses. 
> 
> For #1, the anchored mobiles at the MAG are from one operator 
> and so the addresses are not overloaded. This case is covered 
> by DSMIP6 and as well in this draft.

My understanding of netlmm-proxymip6 is that a MAG is allowed to be
shared between LMAs. Those LMAs could be operated by different
operators.
In this case MNs anchored to the MAG could be from different
operators -> potential address overloading.

> For #2, its not covered in DSMIP6. The use case for this 
> scenario is not generic to MIP6 and so it wont be in DSMIP6. 

I see..

> This document is a result of a document split and the scope 
> is exactly the same as draft-sgundave-mip6-pmip6-02.txt. So, 
> the overlapping scenario is not in the scope of the base document.
> 
> However, the GRE use case was covered in some other draft, 
> covering all the use cases.
> 
> http://www.ietf.org/internet-drafts/draft-muhanna-netlmm-greke
> y-option-00.txt

Yes, I am aware of this draft. Still, the pmip6-ipv4 draft does
not mention about the above cases, use of private IPv4 addresses
in user plane (overloaded or not overloaded) or does not indicate
these are to be solved in other IDs - so a reader is left with a
of lot questions. Some explicit text on acknowledging the above and
then narrowing the scope would be enough imho.

> > describing policy profile information and/or IPv4 HoA 
> assignment from 
> > LMA. What will be provided e.g. by DHCP to the MN as the 
> default GW? 
> > There isn't anything about this in PBUs, right?
> 
> 

Ok. But in a 'normal' DSMIP6 case the MN knows where to route packets
as it is aware of MIP and the tunnel it terminates. I think the PMIP
case is different from MN point of view and not for DSMIP6 to solve.

> issue/question for DSMIP6 and is not exclusive for PMIP6-IPv4 draft.

I see.. Just for my clarification. Isn't it is possible that MN's stack
is unaware of PMIP and blindly does interface config based on DHCP? And
when DHCP is used it shouldn't matter whether the link model is p2p or
not?

Cheers,
	Jouni

---

From: "Sri Gundavelli" <[email-masked]>
Date: Wed, 2 May 2007 14:47:00 -0700

Hi Jouni,

Please see inline.

> operators -> potential address overloading.

Yes, multiple LMA's may be deployed in a PMIP domain and a
MAG may have sessions with multiple LMA's. But the scope of
the domain is typically assumed to be under one admin domain
and so the overloading of private address space is not covered.
But, I see your point and probably we need to state this 
explicitly on the assumed scope.

> then narrowing the scope would be enough imho.

Ok. Sure. We will try to state the scope explicitly and clear any
ambiguity there.

> case is different from MN point of view and not for DSMIP6 to solve.

Even for PMIP, the mobile has a p2p link and that's where all the
packets can be routed, its a default route over that link and the
MAG can route the packets to the LMA. So, the case of the mobile 
having a tunnel to the HA in DSMIP case and the case in PMIP with
the mobile having a p2p link to the MAG, pretty much brings the
same interface/route configuration on the mobile node. But, we
definitely need to take some implementation input for different
platforms Win32, NetBSD and Linux, to see if there is an issue
in routing and if there is a need for default router configuration.
If it turns out that the default-router option is required only
for PMIP, we will bring the option back into the document.

> when DHCP is used it shouldn't matter whether the link model is p2p or

MN's stack is not aware of PMIP. Sure, we can take that approach of
mobile not having to know about the link model. If we provide the
default-router config, pretty much the link model is not in picture.
We need to open discussions on this thread in MIP6/DSMIP6 and also
seek some client implementation input from MIP4 WG. 

Thanks
Sri

---

From: <[email-masked]>
Date: Thu, 3 May 2007 13:56:56 +0200

Hi Sri,

[snip]

> same interface/route configuration on the mobile node. But, we
 
I see.. I guess the DHCP server in MAG could e.g. use IPv4-HoA as
def router or just come up with something that looks about correct ;-)

> for PMIP, we will bring the option back into the document.

Ok.

[snap]

Cheers,
	Jouni