Subject: [netlmm] questions on when to use IPv4 transport and encapsulation

From: "Yingzhe Wu" <[email-masked]>
Date: Tue, 16 Dec 2008 11:38:19 -0800

Dear authors of PMIP6 - IPv4 support,

I have few questions on the latest version of the document and hope you can
clarify. These questions are originated from within WiMAX Forum.

1. The spec currently mandates both IPv6 and IPv4 addresses on the MAG and
LMA:

   o  The local mobility anchor and the mobile access gateway MUST be
      configured with IPv6 global addresses, even when they are in IPv4-
      only network.  When using IPv4 transport, it is not required that
      there is IPv6 routing enabled between the local mobility anchor
      and the mobile access gateway.  However, there must be IPv6
      routing enabled for the configured address locally within the
      host.

The question is how MAG determines what address to use (IPv6 or IPv4) when
sending the PBU, when both addresses are configured and available to use?
Could it be it always try the IPv6 first and if it doesn't work, use IPv4?

2. Also, I have a question on Ipv4 care-of Address option. In section 4.1.1,
it says:

   o  The IPv4 address of the mobile access gateway.  This is the
      address configured on the egress interface of the mobile access
      gateway that sent the Proxy Binding Update message.  This address
      can be obtained from the IPv4 Care-of Address option [ID-DSMIP6
<http://tools.ietf.org/html/draft-ietf-netlmm-pmip6-ipv4-support-06#ref-ID-D
SMIP6> ],
      present in the received Proxy Binding Update message.  If the
      option was not present in the request, this field MUST be set to
      the source address of the IPv4 header of the received Proxy
      Binding Update message.  However, if the received Proxy Binding
      Update message is not sent as an IPv4 packet, this field MUST be
      set to ALL_ZERO value.

But in section 4.2.2, it says:

   o  The IPv4 Care-of Address option [ID-DSMIP6
<http://tools.ietf.org/html/draft-ietf-netlmm-pmip6-ipv4-support-06#ref-ID-D
SMIP6> ] MUST be present.  The
      IPv4 address in the option MUST be set to the mobile access
      gateway's IPv4-Proxy-CoA.

These 2 sections do not seem to be consistent.

Many thanks,

Yingzhe

_______________________________________________
netlmm mailing list
[email-masked]
https://www.ietf.org/mailman/listinfo/netlmm

---

From: Sri Gundavelli <[email-masked]>
Date: Tue, 16 Dec 2008 12:07:55 -0800 (PST)

Hi Yingzhe,

> Could it be it always try the IPv6 first and if it doesn't work, use IPv4?

Its the configuration on the MAG that determines if it should use
IPv4 transport or it can use IPv6 transport. If there is IPv6
routing between LMA and MAG, it can use IPv6 transport for the
signaling messages, else it should use IPv4 transport, the text in
the MAG signaling considerations covers this.

>      Update message is not sent as an IPv4 packet, this field MUST be

It should have said, its the care-of address configured on the MAG.
Will clarify.

>      gateway's IPv4-Proxy-CoA.

Thanks
Sri

---

From: "Vijay Devarapalli" <[email-masked]>
Date: Tue, 16 Dec 2008 15:54:04 -0500

Hi Yingzhe, 

> I have few questions on the latest version of the document 
> and hope you can clarify. These questions are originated from 
> within WiMAX Forum.
> 
> 1. The spec currently mandates both IPv6 and IPv4 addresses 
> on the MAG and LMA:
> 
> The question is how MAG determines what address to use (IPv6 
> or IPv4) when sending the PBU, when both addresses are 
> configured and available to use? Could it be it always try 
> the IPv6 first and if it doesn't work, use IPv4?

The IPv6 address is always used to send the PBU. If IPv4 transport is
used, the IPv6 packet is tunneled in v4. If not, it is sent out as a
native IPv6 packet. The PBU is not an IPv4 packet. 

The MAG is configured with information on when to use IPv4 transport.
The draft currently does not provide a mechanism to dynamically figure
out if IPv4 transport should be used.

Vijay

---

From: [email-masked]
Date: Wed, 17 Dec 2008 13:45:20 +0900

Hi Yingzhe and Vijay

At Tue, 16 Dec 2008 15:54:04 -0500,
> out if IPv4 transport should be used.

This can be set to local configuration. I don't think dynamic
IPv4/IPv6 transport determination.

ryuji

---

From: "Yingzhe Wu" <[email-masked]>
Date: Tue, 16 Dec 2008 22:07:55 -0800

Hi Sri,

Thank you very much for your reply. However, it is still not clear to me.

> the MAG signaling considerations covers this.
How the MAG knows if there is IPv6 routing between LMA and MAG? Unless it
tries the IPv6 first and it works. Then there is no need for IPv4 I suppose.
OTOH, suppose MAG always uses the IPv4 if it is available and will succeed
in most cases (assuming the general availability of IPv4 transport) then it
will never exercise its IPv6 part.
>From the MAG signaling consideration section, I couldn't get enough
information out of it.

> It should have said, its the care-of address configured on the MAG.
What's unclear to me is if Ipv4 Care-of address option is optional in PBU or
not. In section 4.1.1, it says it may not be there, but 4.2.2 says MAG must
include it.
>From my understanding of DSMIP6, this option is mandatory to be included.

Br/
Yingzhe

> -----Original Message-----
> From: Sri Gundavelli [mailto:[email-masked]]
> Sent: Tuesday, December 16, 2008 12:08 PM
> To: Yingzhe Wu
> Cc: 'Netlmm'
> Subject: Re: [netlmm] questions on when to use IPv4 transport and
> encapsulation
> 
> Hi Yingzhe,
> 
> 
>

---

From: "Yingzhe Wu" <[email-masked]>
Date: Tue, 16 Dec 2008 22:10:36 -0800

Thanks Vijay,

I think it is better if the document provides some guidance on what IP
version to use as the transport when both are available.

-Yingzhe

> From: Vijay Devarapalli [mailto:[email-masked]]
> Sent: Tuesday, December 16, 2008 12:54 PM
> To: Yingzhe Wu; Netlmm
> Subject: RE: [netlmm] questions on when to use IPv4 transport and
> encapsulation
> 
> Hi Yingzhe,
>

---

From: Sri Gundavelli <[email-masked]>
Date: Tue, 16 Dec 2008 22:15:36 -0800 (PST)

Hi Yingzhe,

> will never exercise its IPv6 part.

This should be pre-configured information. If the MAG were to be a mobile
device, I'd agree with the approach of retrying both the modes. On a
fixed device such as a MAG, this should be simply a policy decision. May
be a protocol configuration flag should help ?

> From my understanding of DSMIP6, this option is mandatory to be included.

Ok, I understand the inconsistency part now. The approach is as specified
in DSMIP. This option is required. Will clarify this. I agree, this is not
clear.

Thanks
Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Tue, 16 Dec 2008 22:21:24 -0800 (PST)

> be a protocol configuration flag should help ?

Adding more to this. If we assume that a single flag is not sufficient, as
some LMA's may be reachable over IPv6 and some over IPv4 in the same
PMIP domain, then this needs to endup in the MN's policy profile, where we
provide the LMA address. Or, to simplify this, assuming all LMA's are
reachable over one transport, a config flag will be sufficient.

Sri

---

From: "Yingzhe Wu" <[email-masked]>
Date: Tue, 16 Dec 2008 22:52:07 -0800

Hi Sri,

> > device, I'd agree with the approach of retrying both the modes.
Not sure what's the different between MAG being mobile or fixed with respect
to PBU retry in different IP version?

>From LMA perspective, there aren't many concerns. It supports either IPv6 or
both IPv4/IPv6 and this information is in mobile policy profile.
>From MAG perspective, if it only support IPv4 transport, I wander where does
it get the IPv6 address from, which is required from the document? And if it
indeed has the IPv6 address, why would it still use IPv4?
I suppose the IPv6 addresses on MAG and LMA are necessary for the security
association to be based on.

Thanks,
Yingzhe.

> Sent: Tuesday, December 16, 2008 10:21 PM
> To: Yingzhe Wu
> Cc: 'Netlmm'
> >>  in most cases (assuming the general availability of IPv4 transport)
> then
> >>  it

---

From: Sri Gundavelli <[email-masked]>
Date: Tue, 16 Dec 2008 23:10:02 -0800 (PST)

Hi Yingzhe,

> to PBU retry in different IP version?

The reason I say that is, if the MAG were to be mobile and moving
between access networks, the reachability over a given transport cannot
be assumed, as the topology keeps changing and so does the transport.
In a fixed network, its predictable.

> indeed has the IPv6 address, why would it still use IPv4?

As discussed at the last IETF, the requirement for the IPv6 address
configuration should not equate to enabling IPv6 transport between the
LMA and MAG. We just need the LMA's and MAG's to be assigned an IPv6
address, does not require V6 transport routing. This can be achieved
multiple ways:

- There can be fixed IPv6 address block for all the MAG's/LMA's in a PMIP
domain.

- Some one else suggested, mapped addresses.

Now, the decision on what transport to use, is a configuration decision.
As an administrator I may provision my MAG's to state, LMA1 and LMA2 are
reachable over IPv4 transport and LMA3 is reachable over IPv6 transport.
Or, this can be in a MN's policy profile, and that is available to the
MAG. The same policy profile that provides the LMA's addresses can provide
this transport information to a given MAG, on a per Mobile/LMA basis.

> association to be based on.

Yes. The signaling messages are still based on IPv6/MIP6, security is 
based on IPv6 transport addresses and so we require IPv6 on the boxes.

Regards
Sri

---

From: Ryuji Wakikawa <[email-masked]>
Date: Wed, 17 Dec 2008 16:44:25 +0900

Hi Sri,

On 2008/12/17, at 15:21, Sri Gundavelli wrote:

>>> in most cases (assuming the general availability of IPv4  
>>> transport) then
>>> it

Can MAG know the transport version dynamically when it discovers LMA  
for MN?

ryuji

---

From: Julien Laganier <[email-masked]>
Date: Wed, 17 Dec 2008 11:13:38 +0100

On Tuesday 16 December 2008, Yingzhe Wu wrote:
> 1. The spec currently mandates both IPv6 and IPv4 addresses on the
> MAG and LMA:
>
>       configured with IPv6 global addresses, even when they are in
> IPv4- only network.

By the way:

I think in the above it should be global unicast addresses rather than 
global addresses.

Also, wouldn't the use of IPv6 Unique Local Unicast Addresses [RFC4193] 
acceptable for the MAG and LMA, provided that routing works between the 
addresses (e.g. MAG and LMA belong to the same site, or there's an 
explicit routing agreement between the MAG and LMA's sites)?

--julien

---

From: Behcet Sarikaya <[email-masked]>
Date: Wed, 17 Dec 2008 07:52:51 -0800 (PST)

Hi Sri,
  Given the current deployment status and trends, I would almost assure that IPv6 transport would be a given between MAG and LMA.

IPv4 support document should mainly be for supporting legacy MN's sticking to IPv4.

Regards,

Behcet

________________________________
From: Sri Gundavelli <[email-masked]>
To: Yingzhe Wu <[email-masked]>
Cc: Netlmm <[email-masked]>
Sent: Wednesday, December 17, 2008 1:10:02 AM
Subject: Re: [netlmm] questions on when to use IPv4 transport and encapsulation

Hi Yingzhe,

Regards
Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 09:34:18 -0800 (PST)

Hi Ryuji,

On Wed, 17 Dec 2008, Ryuji Wakikawa wrote:

> Can MAG know the transport version dynamically when it discovers LMA for MN?
>

LMA discovery is not within the scope of 5213 or this document. We assumed
the MAG is provided with the LMA address, it can come from the mobile
node's policy profile. The use of a specific transport, or the point that
the MAG and the mobile node's LMA are seperated by a IPv4 cloud, is another
piece of information that can come from the policy profile. So, dynamic
determination of what transport to use, probably we cant add it here,
it can probably go with the LMA discovery.

Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 09:40:38 -0800 (PST)

> I think in the above it should be global unicast addresses rather than

Sure.

> explicit routing agreement between the MAG and LMA's sites)?

If there is reachability over IPv6 transport, using any form of
addressing and when there is IPv6 routing, then there is really no need
for IPv4 transport. We dont disallow that configuration. The use of IPv4
transport goes with the assumption that there is no IPv6 routing enabled.

Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 09:44:06 -0800 (PST)

Hi Behcet,

>  Given the current deployment status and trends, I would almost assure that IPv6 transport would be a given between MAG and LMA.

I hope and wish for that as well. However, the reality is still
IPv4-only transport in most networks and we need to support that
configuration as well.

Sri

---

From: Julien Laganier <[email-masked]>
Date: Wed, 17 Dec 2008 18:51:11 +0100

On Wednesday 17 December 2008, Sri Gundavelli wrote:
> >>    o  The local mobility anchor and the mobile access gateway MUST
> >> be configured with IPv6 global addresses, even when they are in
> >> IPv4- only network.
> >
> > By the way:
> >
> > I think in the above it should be global unicast addresses rather
> > than global addresses.
>
> Sure.
>
> > Also, wouldn't the use of IPv6 Unique Local Unicast Addresses
> > [RFC4193] acceptable for the MAG and LMA, provided that routing
> > works between the addresses (e.g. MAG and LMA belong to the same
> > site, or there's an explicit routing agreement between the MAG and
> > LMA's sites)?
>
> addressing and when there is IPv6 routing, then there is really no
> need for IPv4 transport. We dont disallow that configuration. The use
> of IPv4 transport goes with the assumption that there is no IPv6
> routing enabled.

Well, if the draft says that the local mobility anchor and the mobile 
access gateway MUST be configured with IPv6 global unicast addresses, 
that seems to exclude IPv6 unique local unicast addresses (and also 
IPV4-mapped IPv6 address BTW)
 
--julien

---

From: Behcet Sarikaya <[email-masked]>
Date: Wed, 17 Dec 2008 10:15:03 -0800 (PST)

________________________________
From: Sri Gundavelli <[email-masked]>
To: Behcet Sarikaya <[email-masked]>
Cc: Yingzhe Wu <[email-masked]>; Netlmm <[email-masked]>
Sent: Wednesday, December 17, 2008 11:44:06 AM
Subject: Re: [netlmm] questions on when to use IPv4 transport and encapsulation

Hi Behcet,

Sri

[behcet] I think Raj pointed this out before. If the situation is as you said above then PMIPv6 does not have a lot of chances of deployment, the protocol of choice would be PMIPv4 as in WiMAX. 
So doing a lot of spec work for something that is probably not going to be used is not of much value, I would say.

---

From: "Yingzhe Wu" <[email-masked]>
Date: Wed, 17 Dec 2008 11:19:59 -0800

Hi Sri,

> address, does not require V6 transport routing. This can be achieved
YZ> But if MAG can get an IPv6 global unicast address from the ISP, there
must be IPv6 transport guaranteed, isn't it?

> - There can be fixed IPv6 address block for all the MAG's/LMA's in a
YZ> what is this "fixed IPv6 address block"?

> - Some one else suggested, mapped addresses.
YZ> can we safely assume security association can be established based on
Ipv4 mapped Ipv6 address?

> >>>>  Thank you very much for your reply. However, it is still not
> clear
> >> to me.
> >>>>
> >>>>  tries the IPv6 first and it works. Then there is no need for IPv4
> I
> >>>>  suppose.
> >>>>  OTOH, suppose MAG always uses the IPv4 if it is available and
> will
> >> succeed
> transport)
> >> Adding more to this. If we assume that a single flag is not
> sufficient,
> >> as
> >> PMIP domain, then this needs to endup in the MN's policy profile,
> where
> >> we

---

From: "Yingzhe Wu" <[email-masked]>
Date: Wed, 17 Dec 2008 11:32:19 -0800

Hi Julien, Sri,

This is my concern too. If we mandating IPv6 global unicast address, then it
seems in no case we need IPv4 transport.

For non-global IPv6 address (local unique or IPv4 mapped), the usage
scenario seems to be limited to Intra-site only, where security
establishment does not seem to be a concern (even in this case, IPv4
transport does not seen to be needed). For inter-site or global mobility,
how can one make sure security association between MAG and LMA based on
non-global IPv6 address is adequately addressed?

Thanks,
Yingzhe

> From: [email-masked] [mailto:[email-masked]] On
> Behalf Of Julien Laganier
> Sent: Wednesday, December 17, 2008 9:51 AM
> To: Sri Gundavelli
> Cc: [email-masked]

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 11:45:14 -0800 (PST)

Hi Yingzhe,

> must be IPv6 transport guaranteed, isn't it?

The address configured on the MAG need not be from the local
ISP. It can be a IPv6 prefix block within the local LMA scope.
If there is IPv6 address assignment from the local ISP and
if there is IPv6 routing to the home, no need for IPv4
transport in that configurations.

>> - There can be fixed IPv6 address block for all the MAG's/LMA's in a

>> PMIP

Addresses owned by the LMA. There can be few addresses that
are configured on the MAG, topologically owned by the LMA,
just as the MNP's.

> Ipv4 mapped Ipv6 address?

If the mapped addresses are based on IPv4 addresses, that do not
overlap within the scope of a given LMA, then its safe.

Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 14:01:42 -0800 (PST)

> IPV4-mapped IPv6 address BTW)

We currently require "IPv6 global address". Probably, that should stay
that way and not change to "IPv6 global unicast address", to support
the use of other form of IPv6 addresses with local scoping or mapped
addresses.

Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 14:15:08 -0800 (PST)

Hi Yingzhe,

> non-global IPv6 address is adequately addressed?

There is some disconnect. To clarify further.

We need an IPv6 address to be configured on each of the MAG. This is
a very simple requirement, let the LMA reserve few IPv6 addresses to
be used on the MAG's in Proxy Mobile IPv6 domain. This is not requiring
IPv6 transport, or reachability over IPv6. The access network is not
required to have IPv6 routing enabled. This address can indeed be a
global unicast address, mapped address or addresses with other scope.
Requiring this does not eliminate the need for IPv4 transport or
mandate IPv6 routing. This requirement for IPv6 address configuration,
is because the signaling is still based on IPv6/Mobile IPv6, the
packets are still IPv6 packets encapsulated in IPv4 payload, the
security is IPsec applied on the inner IPv6 packet. We are using IPv4
only as a transport and not beyond that.

Sri

---

From: "Alper Yegin" <[email-masked]>
Date: Thu, 18 Dec 2008 00:51:47 +0200

Current draft-ietf-netlmm-pmip6-ipv4-support-07.txt spec says:

	However, the local
      mobility anchor must not be behind a NAT and must be using a
      globally routable IPv4 address.

We shouldn't be preventing use of PMIP6 in private networks. For that, the
above text gets in the way and mandate on the global IPv4 address should be
removed.

Alper

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 14:54:42 -0800 (PST)

Hi Alper,

> above text gets in the way and mandate on the global IPv4 address should be

We allow the MAG to be behing a private network. However, we dont
allow LMA to be behind in a private network, as such usage is
remote and that makes the solution complex. As we discussed in the
past, we just restricted this to the common case.

Sri

---

From: "Yingzhe Wu" <[email-masked]>
Date: Wed, 17 Dec 2008 22:03:42 -0800

Hi Sri,

Thanks for the clarification, as none of this information is currently
captured by the document.

To make an example, assuming we are using PMIP6 inter-domain. During access
authentication, both IPv4 and IPv6 LMA addresses are available to the MAG,
as well as mobile policy profile. If only IPv4 transport is available to the
MAG, the source IPv6 address of inner packet (PBU encapsulated by IPv4) is
either:
1) downloaded from the LMA, as part of the address pool LMA manages (I
suppose this should be part of the mobile policy profile?)
2) IPv4 mapped IPv6 address, where the IPv4 is MAG's IPv4 address. Assuming
IPsec SA can be established based on mapped address, but since MAG can be
behind NAT and address not unique, there may be another MAG using the same
IPv4 mapped IPv6 address, how to differentiate security associations between
these 2 MAGs?

Thanks,
Yingzhe

> Sent: Wednesday, December 17, 2008 2:15 PM
> To: Yingzhe Wu
> Cc: 'Julien Laganier'; [email-masked]

---

From: Ryuji Wakikawa <[email-masked]>
Date: Thu, 18 Dec 2008 15:22:53 +0900

Hi Sri,

On 2008/12/18, at 2:34, Sri Gundavelli wrote:

>>> On a
>>> sufficient, as
>>> where we

adding a flag of transport type in policy profile might be better.
We should not mandate single transport for all LMAs.

> it can probably go with the LMA discovery.

agree Let's not add dynamic determination in this spec.

ryuji

---

From: Ryuji Wakikawa <[email-masked]>
Date: Thu, 18 Dec 2008 15:27:44 +0900

> past, we just restricted this to the common case.

This was discussed in NETLMM meetings or IETF ML a few months ago.
We reached to the consensus that LMA behind NAT is out of scope.
PMIP operators should have at least one global address for LMA.

ryuji

---

From: Ryuji Wakikawa <[email-masked]>
Date: Thu, 18 Dec 2008 15:34:52 +0900

Hi Yingzhe

> suppose this should be part of the mobile policy profile?)

MAG's address in mobile policy profile? Why is this?

> IPv4 mapped IPv6 address, how to differentiate security associations  

If there is two or more NAT boxes configured with the same private  
subnet, duplication of IPv4 mapped address can be occurred.
There is no way to differentiate two SA for the same address..
Operators should not assign the same private subnet prefix for  
different private network (different NAT).

We can clearly mention that MAG's IPv6 addresses must be unique in  
PMIP domain.

ryuji

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 22:36:45 -0800 (PST)

Hi Yingzhe,

> captured by the document.

Ok. We will clarify on the MAG/LMA IPv6 address configuration.

> suppose this should be part of the mobile policy profile?)

Its not dynamically downloaded. All the MAG's that are part of
a Proxy Mobile IPv6 domain are configured with IPv6 addresses
from a specific prefix block.

Ex: Cafe::/64 prefix block is reserved for all the MAG's and LMA's
     in that PMIP domain. Every LMA and MAG is given an IPv6 address
     from this prefix block.

> IPv4 mapped IPv6 address, how to differentiate security associations between

Right. As I said, as long as there is no overlap of the private address
from which these addresses are derived, there is no collision. Certainly
this is not recommended if MAG's are behind a NAT and using private IPv4
addresses. If the MAG's are using global IPv4 addresses, a mapped IPv6
address uniquely identifies only one MAG.

We did not go into the details of how IPv6 addresses should be configured.
We just require a unique IPv6 address on each MAG.

Regards
Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Wed, 17 Dec 2008 22:37:54 -0800 (PST)

Hi Ryuji,

> We should not mandate single transport for all LMAs.

I agree. LMA address and the tranport to be used comes from the
profile.

Sri

---

From: "Alper Yegin" <[email-masked]>
Date: Thu, 18 Dec 2008 11:09:12 +0200

Hi Sri,

> past, we just restricted this to the common case.

MAG and LMA being in two different private domains is "remote and complex to
handle", I agree.
MAG and LMA being in the same private domain is trivial -- it just works.
I presume it is the former you wanted to restrict, not the latter. 
If you agree, we can work out a text towards that objective.

Alper

---

From: Julien Laganier <[email-masked]>
Date: Thu, 18 Dec 2008 10:17:29 +0100

Sri,

On Wednesday 17 December 2008, Sri Gundavelli wrote:
> > Well, if the draft says that the local mobility anchor and the
> > mobile access gateway MUST be configured with IPv6 global unicast
> > addresses, that seems to exclude IPv6 unique local unicast
> > addresses (and also IPV4-mapped IPv6 address BTW)
>
> We currently require "IPv6 global address". Probably, that should
> stay that way and not change to "IPv6 global unicast address", to
> support the use of other form of IPv6 addresses with local scoping or
> mapped addresses.

What's the definition of IPv6 global address?

--julien

---

From: "Premec, Domagoj" <[email-masked]>
Date: Thu, 18 Dec 2008 13:24:17 +0100

Sri,

> from a specific prefix block.

A MAG can be part of multiple PMIP domains. A typical use case in WiMAX is that MAG and LMA are located in separate administrative domains and there are roaming agreements in place. If the MAG is in the IPv4-only network, how does it come up with its IPv6 address needed for PMIP6 signalling? In a roaming enviroment the "fixed IPv6 address block" approach won't work. I guess that's where the dynamic download of MAG's address comes handy.

domagoj

> From: [email-masked] 
> [mailto:[email-masked]] On Behalf Of Sri Gundavelli
> Sent: 18. prosinac 2008 07:37
> To: Yingzhe Wu
> Cc: [email-masked]; 'Julien Laganier'
> Subject: Re: [netlmm] questions on when to use IPv4 
> transportand encapsulation
> 
> Hi Yingzhe,
> 
> 
> >>> This is my concern too. If we mandating IPv6 global 
> unicast address,
> >> then it
> >>> how can one make sure security association between MAG 
> and LMA based
> >> on

---

From: Sri Gundavelli <[email-masked]>
Date: Thu, 18 Dec 2008 09:48:03 -0800 (PST)

Hi Julien,

> What's the definition of IPv6 global address?

I intended to say, "IPv6 globally unique address". This includes:

- Unique Local IPv6 Unicast Addresses, RFC 4193
- IPv6 Global Unicast Address, RFC 3587
- IPv4-mapped IPv6 address, RFC 4291

If you disagree with the definition, we can spell this out, or
please provide a better definition that does not exclude any
form of addresses.

Thanks
Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Thu, 18 Dec 2008 09:48:07 -0800 (PST)

Hi Alper,

> If you agree, we can work out a text towards that objective.

Yes. MAG and LMA in the same private domain, or same routing domain
with no translation requirement, should work fine. Yes, we can add
clarifying text to this affect.

Regards
Sri

---

From: Sri Gundavelli <[email-masked]>
Date: Thu, 18 Dec 2008 09:57:02 -0800 (PST)

Hi Domagoj,

> A MAG can be part of multiple PMIP domains. A typical use case in WiMAX is that MAG and LMA are located in separate administrative domains and there are roaming agreements in place. If the MAG is i…

This chaining is really not in scope. But, even for the scenario where
the MAG is part of multiple domains, its still requires one globally
unique address that does not collide with any other IPv6 address in
any of those domains its supporting.

- If the MAG is using a public IPv4 address, a IPv4-mapped IPv6 address
will be sufficient.

- Else, reserve a prefix block for all the MAG's. Any ways, when we define
the security relation between the MAG and LMA's, there are many pieces

Downloading MAG's IPv6 address from LMA can be done. But, given a very
simple requirement that the MAG needs a globally unique IPv6 address,
I dont see why we should specify that, as I dont understand why
configuring a globally unique IPv6 address is an issue.

Regards
Sri

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From: Ryuji Wakikawa <[email-masked]>
Date: Fri, 19 Dec 2008 17:44:58 +0900

Hi Sri, and Domagoj,

At Thu, 18 Dec 2008 09:57:02 -0800 (PST),
> configuring a globally unique IPv6 address is an issue.

I agree with Sri. It's much simpler to assume that MAG has global
unique IPv6 address. 

Alternatively, we can assume that MAG has an IPv6 addesss used for
PMIP signaling. Then, how to assign the IPv6 address can be just out
of scope.

ryuji

---

From: Ryuji Wakikawa <[email-masked]>
Date: Fri, 19 Dec 2008 17:51:29 +0900

Hi Sri,

At Thu, 18 Dec 2008 09:48:03 -0800 (PST),
> - IPv4-mapped IPv6 address, RFC 4291 

The third address can be globally unique if it is generated from
global IPv4 address. We need more clarification about the uniqueness
of IPv4 mapped address generated from private address. 

We actually don't need global uniqueness, but uniqueness should be
guaranteed within a PMIP domain.

regards,
ryuji

---

From: Julien Laganier <[email-masked]>
Date: Sat, 20 Dec 2008 11:44:48 +0100

Hi Sri,

I think it would be good to spell it out.

--julien

On Thursday 18 December 2008, Sri Gundavelli wrote:
> >> support the use of other form of IPv6 addresses with local scoping
> >> or mapped addresses.
> >

-- 
--julien