Subject: [nemo] RFC 3963: Clarifications if the MR is MN too

From: "Jean-Michel COMBES" <[email-masked]>
Date: Mon, 9 May 2005 18:02:28 +0200

Hi,

The RFC 3963 says in:

(1) Section 3, p5
"When the Mobile Router moves away from the home link and attaches to a new
access router, it acquires a Care-of Address from the visited link.  The
Mobile Router can at any time act either as a Mobile Host or as a Mobile
Router. It acts as a Mobile Host as defined in [1] for sessions it
originates and provides connectivity to the Mobile Network.  As soon as the
Mobile Router acquires a Care-of Address, it immediately sends a Binding
Update to its Home Agent as described in [1]. When the Home Agent receives
this Binding Update, it creates a cache entry binding the Mobile Router's
Home Address to its Care-of Address at the current point of attachment."

(2) Section 4.1, p7
"A new flag (R) is included in the Binding Update to indicate to the Home
Agent whether the Binding Update is coming from a Mobile Router and not from
a mobile node.  The rest of the Binding Update format remains the same as
defined in [1]."

(3) Section 4.1, p7
"Mobile Router Flag (R)
The Mobile Router Flag is set to indicate to the Home Agent that the Binding
Update is from a Mobile Router. If the flag is set to 0, the Home Agent
assumes that the Mobile Router is behaving as a Mobile Node, and it MUST NOT
forward packets destined for the Mobile Network to the Mobile Router.

Assuming that a MR is MN too, as described in (1), my questions are: 
- (2) seems to indicate that such a MR has to send 2 BU: one with R=0 for
MIPv6 and one with R=1 for MIPv6. Am I wrong?
- (3) seems to indicate that a HA cannot manage NEMO and MIPv6. Am I wrong?

Thanks for your help.

Regards.

JMC.

France Telecom - R&D Division - MAPS/NSS   
Jean-Michel COMBES, Internet/Intranet Security
E-Mail: [email-masked]
Phone: +33 (0)1 45 29 45 94
Fax: +33 (0)1 45 29 65 19
Mobile: +33 (0)6 07 29 30 16

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From: Alexandru Petrescu <[email-masked]>
Date: Tue, 10 May 2005 16:25:01 +0200

Jean-Michel COMBES wrote:

> Hi,
> 
> The RFC 3963 says in:
> 
> (1) Section 3, p5 "When the Mobile Router moves away from the home
> link and attaches to a new access router, it acquires a Care-of
> Address from the visited link.  The Mobile Router can at any time act
> either as a Mobile Host or as a Mobile Router. It acts as a Mobile
> Host as defined in [1] for sessions it originates and provides
> connectivity to the Mobile Network.  As soon as the Mobile Router
> acquires a Care-of Address, it immediately sends a Binding Update to
> its Home Agent as described in [1]. When the Home Agent receives this
> Binding Update, it creates a cache entry binding the Mobile Router's 
> (2) Section 4.1, p7 "A new flag (R) is included in the Binding Update
> to indicate to the Home Agent whether the Binding Update is coming
> from a Mobile Router and not from a mobile node.  The rest of the
> Binding Update format remains the same as defined in [1]."
> 
> (3) Section 4.1, p7 "Mobile Router Flag (R) The Mobile Router Flag is
> set to indicate to the Home Agent that the Binding Update is from a
> Mobile Router. If the flag is set to 0, the Home Agent assumes that
> the Mobile Router is behaving as a Mobile Node, and it MUST NOT 
>  - (2) seems to indicate that such a MR has to send 2 BU: one with
> R=0 for MIPv6 and one with R=1 for MIPv6. Am I wrong?

In our implementation one R-BU is sufficient to "bind" both the HoA and
the complete MNP.  It was not in the intention to have two BUs sent one
for MH and one for MR.

> - (3) seems to indicate that a HA cannot manage NEMO and MIPv6. Am I

Terminology-wise, "If the flag is set to 0, the Home Agent assumes that
the Mobile Router is behaving as a Mobile Node" should probably better
say "Mobile Host" instead of "Mobile Node".  That would clarify things I
believe.

Implementations that I know of have a HA that either supports MH or both
MH/MR (a MN is an MH and MR actually, by the RFC3775 definitions I believe).

My oppinion,

Alex

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From: Thierry Ernst <[email-masked]>
Date: Wed, 11 May 2005 15:11:46 +0900

Hi,

Yes, the HA supports both operation, but I think the question is
about doing this simultaneously. 

On the MN side, the current text in RFC 3963 doesn't mean the MN can act
simultaneously both as a MH and a MR ; and, if it does, does it need to
send only 1 BU or 2 BUs.

I think the authors of the RFC should clarify this point (i.e. what is
the correct interpretation, from an implementation point of view, of the
possibility for a MN to act both as a MH and a MR).

Thierry

> > Address from the visited link.  The Mobile Router can at any time
> > act either as a Mobile Host or as a Mobile Router. It acts as a
> > Mobile Host as defined in [1] for sessions it originates and
> > provides connectivity to the Mobile Network.  As soon as the Mobile
> > Router acquires a Care-of Address, it immediately sends a Binding
> > Update to its Home Agent as described in [1]. When the Home Agent
> > receives this Binding Update, it creates a cache entry binding the
> > Mobile Router's Home Address to its Care-of Address at the current
> > point of attachment."
> > 
> > (2) Section 4.1, p7 "A new flag (R) is included in the Binding
> > Update to indicate to the Home Agent whether the Binding Update is
> > coming from a Mobile Router and not from a mobile node.  The rest of
> > the Binding Update format remains the same as defined in [1]."
> > 
> > (3) Section 4.1, p7 "Mobile Router Flag (R) The Mobile Router Flag
> > is set to indicate to the Home Agent that the Binding Update is from
> > a Mobile Router. If the flag is set to 0, the Home Agent assumes
> > that the Mobile Router is behaving as a Mobile Node, and it MUST NOT
> In our implementation one R-BU is sufficient to "bind" both the HoA
> and the complete MNP.  It was not in the intention to have two BUs
> sent one for MH and one for MR.
> 
> Terminology-wise, "If the flag is set to 0, the Home Agent assumes
> that the Mobile Router is behaving as a Mobile Node" should probably
> better say "Mobile Host" instead of "Mobile Node".  That would clarify
> things I believe.
> 
> Implementations that I know of have a HA that either supports MH or
> both MH/MR (a MN is an MH and MR actually, by the RFC3775 definitions
> I believe).

---

From: Ranjitsinh Wable <[email-masked]>
Date: Wed, 11 May 2005 12:38:13 +0530

Hi,

I have one point to mention on this.

Whether it is really need to explicitly mentioning the simultaneous working 
of the MN as MH and MR.
MN is working as MR operation is superset of MN working as MH.
So once the working of MR is explained there is no need of mentioning the 
how MH work simultenously.
Also there is no need of separate BU for the same. IMHO it is implicit.

Let me know your views on the same.

Regards,

Wable

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From: Vijay Devarapalli <[email-masked]>
Date: Wed, 11 May 2005 11:27:39 -0700

> MIPv6 and one with R=1 for MIPv6. Am I wrong?

nope. just one BU is enough. when the HA processes the R bit in
the BU, it sets up forwarding for the MNP in addition to creating
a binding cache for the home address as described in RFC 3775.

> - (3) seems to indicate that a HA cannot manage NEMO and MIPv6.

nope. the HA can at the same time support MIPv6 MNs and NEMO MRs.
if the R bit in the BU is not set, the HA just creates a binding
cache for the home address, defends the home address and tunnels
packets meant for the home address to the current CoA. if the R
bit in the BU is set, the HA does the above *and* sets up forwarding
for the MNP.

Vijay

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From: Ryuji Wakikawa <[email-masked]>
Date: Thu, 12 May 2005 11:16:32 +0900

Hi all

On 2005/05/12, at 3:27, Vijay Devarapalli wrote:

>> receives
>> Assuming that a MR is MN too, as described in (1), my questions  
>> are: - (2) seems to indicate that such a MR has to send 2 BU: one  
>> with R=0 for

Yes, HA can create a binding for HoA by the NEMO BU,  but I want to  
clarify
whether MR can start Route Optimization for the MR's HoA with the  
registered binding?
I think possible, but this should not be mandated.

regards,
ryuji

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From: Vijay Devarapalli <[email-masked]>
Date: Thu, 12 May 2005 16:42:18 -0700

> whether MR can start Route Optimization for the MR's HoA with the  

yes. everything the MN can do in RFC 3775, the MR can do for sessions
started by itself using its own HoA.

> I think possible, but this should not be mandated.

thats correct. the MR can always use reverse tunneling for its own
sessions as well.

Vijay