Subject: [MOBILE-IP] WG Last Call - draft-ietf-mobileip-3gwireless-ext-01.txt

From: Basavaraj Patil <[email-masked]>
Date: Tue, 14 Dec 1999 10:03:27 -0600

Hi,

We would like to progress the "Mobile IP Based Micro Mobility
Management Protocol in the Third Generation Wireless Network"
(draft-ietf-mobileip-3gwireless-ext-01.txt) I-D on the standards
track.

As per process we are issuing a WG last call on this I-D. Please
provide comments and feedback within the next two weeks.

WG Last call issued : Dec 14, 1999

Regards,
-Basavaraj
-Phil

---

From: Masanobu Yuhara <[email-masked]>
Date: Wed, 15 Dec 1999 16:36:37 +0900

I think this draft (draft-ietf-mobileip-3gwireless-ext-01.txt) should
clarify how Mobile-IP (RFC2002) is utilized in this cdma2000
environment.

From what I read from the document, "Mobile Node" in Fig.1 does not
seem to be a RFC2002-Mobile-Node. Likewise, "PDSN", where FA resides,
may not be a RFC2002-FA, "HA" in Fig.1 may not be a
RFC2002-Home-Agent. I thought so because the draft says, in the
Registration Request:
        Care-of Address field = RNN's address  (!= PDSN's address)
        Home Agent field      = PDSN's address (!= HA's address)
        Home Address field    = zero (!= MN's Home Address)
Also, it is the RNN that issues a Registration Request, not the Mobile
Node.

My first guess was that in this scenario, Mobile Node (in Fig.1) does
not have to support Mobile-IP (it may be even without IP support?) and
the RNN plays a role of RFC2002-Mobile-Node on behave of the Mobile
Node. But this may be wrong.

I'm confused.

I'd like the authors to clarify how Mobile-IP is used.
A figure of protocol stacks may help understanding.

------
Masanobu Yuhara         [email-masked]
Fujitsu Laboratories Ltd.

---

From: Pete McCann <[email-masked]>
Date: Wed, 15 Dec 1999 10:02:41 -0600

Hi, Masanobu,

Your guesses below are essentially correct - I suspect many people may
have some similar trouble understanding this draft upon a first
read-through.  Let me try to answer your questions.

3gwireless is intended to be used between an RNN and PDSN, and to
carry directly the octet stream coming from a mobile node's RLP (Radio
Link Protocol) in a way that gives the illusion of transparent, direct
connectivity between the MN and PDSN.  So you are right, the MN is not
involved in sending the registration requests discussed in the draft -
they are sent immediately upon establishment of the MN's RLP
connection with the RNN.  Once this tunnel is set up, the PDSN
receives the octet stream (GRE encapsulated in arbitrary chunks) and
may then terminate the MN's link layer protocol such as PPP and
possibly implement FA functionality (by sending Agent Advertisements
to the MN over the PPP link).  You are right that the MN need not
implement Mobile IP at all; the R-P tunnel provides some degree of
mobility for those MNs that contain only PPP stacks and nothing else.
While the R-P tunnel should not be used for wide-area Internet
mobility, it does extend the coverage area of a single PPP session
beyond that of a single RNN, which is a requirement of the 3GPP2
group.  It also provides a standardized interface between RNNs and
PDSNs.

I hope this helps explain some of the mechanics and motivations behind
the 3gwireless draft.

-Pete

Masanobu Yuhara <[email-masked]> (MY) writes:

MY> I think this draft (draft-ietf-mobileip-3gwireless-ext-01.txt) should
MY> clarify how Mobile-IP (RFC2002) is utilized in this cdma2000
MY> environment.

>> From what I read from the document, "Mobile Node" in Fig.1 does not
MY> seem to be a RFC2002-Mobile-Node. Likewise, "PDSN", where FA resides,
MY> may not be a RFC2002-FA, "HA" in Fig.1 may not be a
MY> RFC2002-Home-Agent. I thought so because the draft says, in the
MY> Registration Request:
MY>         Care-of Address field = RNN's address  (!= PDSN's address)
MY>         Home Agent field      = PDSN's address (!= HA's address)
MY>         Home Address field    = zero (!= MN's Home Address)
MY> Also, it is the RNN that issues a Registration Request, not the Mobile
MY> Node.

MY> My first guess was that in this scenario, Mobile Node (in Fig.1) does
MY> not have to support Mobile-IP (it may be even without IP support?) and
MY> the RNN plays a role of RFC2002-Mobile-Node on behave of the Mobile
MY> Node. But this may be wrong.

MY> I'm confused.

MY> I'd like the authors to clarify how Mobile-IP is used.
MY> A figure of protocol stacks may help understanding.

MY> ------
MY> Masanobu Yuhara         [email-masked]
MY> Fujitsu Laboratories Ltd.

---

From: Masanobu Yuhara <[email-masked]>
Date: Thu, 16 Dec 1999 12:22:49 +0900

Thanks Pete, it gets much clearer.

The followings are what I understand now.
Are these assertions correct?

(1) HA in Fig.1 has nothing to do with this draft.

(2) HA is there because it may be used to deal with Macro-Mobility.
    In that case, Mobile-IP is nested. Inner Mobile-IP is for
    Micro-Mobility and outer Mobile-IP is for Macro-Mobility.
    The extension of this draft is for Micro-Mobility only.
    Macro-Mobility may and may not be used with Micro-Mobility.

(3) If (1) and (2) are correct, then we can summarize the situation as
    follows. MN, RNN, PDSN, HA are those in Fig.1 of the draft.

                +----------+----------+----------+
                | MIP's MN | MIP's FA | MIP's HA |
+---------------+----------+----------+----------+
|Micro-Mobility | RNN(*1)  |   RNN    |   PDSN   | (*1) RNN on behalf of MN
+---------------+----------+----------+----------+
|Macro-Mobility |   MN     |   PDSN   |   HA     |
+---------------+----------+----------+----------+
        Foreign Agent Care-of Addresses are used for both.

    PDSN is a HA for Micro-Mobility's point of view,
    but is also a FA for Macro-Mobility's point of view.

(4) When Micro- and Macro- Mobilities are used in combination,
    protocol stacks look like this:

[MN]      [  RNN   ]    [   PDSN    ]     [     HA     ]       [Corresponding
                                                                Node]

+----+                                                         +----+
|TCP |                                                         |TCP |
+----+                  +---+-------+     +-------+----+       +----+
|IP* |                  |IP*|  IP*  |     | IP*   |IP* |       |IP* |
+----+ . . . . . . . . .+---+-------+ . . +-------+----+ . . . +----+
|PPP |                  |PPP|MIP-tun|     |MIP-tun|
+----+    +----+---+    +---+-------+     +-------+
|RLP |    |RLP |GRE|    |GRE|  IP   |     |  IP   |
+----+    +----+---+    +---+-------+     +-------+
               |R-P|    |R-P|
               +---+    +---+
               | IP|    | IP|
               +---+    +---+

IP*: asterisk is attached to distinguish IP* from encapsulating IP.
MIP-tun: Mobile-IP tunnel (IP-in-IP or GRE or Minimal) from HA to FA (PDSN).
RLP: Radio Link Protocol
Link Layers and below are not shown (except RLP).

(5) This draft only covers the following part.

[MN]      [  RNN   ]    [   PDSN    ]

+----+                  +---+
|any |                  |any|
+----+                  +---+
|PPP |                  |PPP|
+----+    +----+---+    +---+
|RLP |    |RLP |GRE|    |GRE|
+----+    +----+---+    +---+
               |R-P|    |R-P|
               +---+    +---+
               | IP|    | IP|
               +---+    +---+

any: any protocol that can be carried over PPP.

-- masa

------

---

From: Pete McCann <[email-masked]>
Date: Thu, 16 Dec 1999 09:53:13 -0600

Hi, Masanobu,

Yes, your assumptions and diagrams look correct (nice ASCII art).

I would put in a word of caution, though, about calling the RNN an FA
and the PDSN an HA.  It is tempting to draw these analogies with
RFC2002, but they can be misleading - really, 3gwireless is a new
tunnel establishment protocol that is based on Mobile IP (and uses
Mobile IP messages) but which is really different from Mobile IP
in many ways.  I would just say that the RNN establishes a tunnel
to the PDSN, using Mobile IP signaling with the Session Specific
Extension.

Also, the draft is intentionally vague on what protocol is being
carried between the RNN and PDSN (my examples used PPP).  We want to
leave open the possibility that this link layer protocol may change
or that someday layer-3 IP packets could be carried between the RNN
and PDSN.

-Pete

MY> Thanks Pete, it gets much clearer.
MY> The followings are what I understand now.
MY> Are these assertions correct?

MY> (1) HA in Fig.1 has nothing to do with this draft.

MY> (2) HA is there because it may be used to deal with Macro-Mobility.
MY>     In that case, Mobile-IP is nested. Inner Mobile-IP is for
MY>     Micro-Mobility and outer Mobile-IP is for Macro-Mobility.
MY>     The extension of this draft is for Micro-Mobility only.
MY>     Macro-Mobility may and may not be used with Micro-Mobility.

MY> (3) If (1) and (2) are correct, then we can summarize the situation as
MY>     follows. MN, RNN, PDSN, HA are those in Fig.1 of the draft.

MY>                 +----------+----------+----------+
MY>                 | MIP's MN | MIP's FA | MIP's HA |
MY> +---------------+----------+----------+----------+
MY> |Micro-Mobility | RNN(*1)  |   RNN    |   PDSN   | (*1) RNN on behalf of MN
MY> +---------------+----------+----------+----------+
MY> |Macro-Mobility |   MN     |   PDSN   |   HA     |
MY> +---------------+----------+----------+----------+
MY>         Foreign Agent Care-of Addresses are used for both.

MY>     PDSN is a HA for Micro-Mobility's point of view,
MY>     but is also a FA for Macro-Mobility's point of view.

MY> (4) When Micro- and Macro- Mobilities are used in combination,
MY>     protocol stacks look like this:

MY> [MN]      [  RNN   ]    [   PDSN    ]     [     HA     ]       [Corresponding
MY>                                                                 Node]

MY> +----+                                                         +----+
MY> |TCP |                                                         |TCP |
MY> +----+                  +---+-------+     +-------+----+       +----+
MY> |IP* |                  |IP*|  IP*  |     | IP*   |IP* |       |IP* |
MY> +----+ . . . . . . . . .+---+-------+ . . +-------+----+ . . . +----+
MY> |PPP |                  |PPP|MIP-tun|     |MIP-tun|
MY> +----+    +----+---+    +---+-------+     +-------+
MY> |RLP |    |RLP |GRE|    |GRE|  IP   |     |  IP   |
MY> +----+    +----+---+    +---+-------+     +-------+
MY>                |R-P|    |R-P|
MY>                +---+    +---+
MY>                | IP|    | IP|
MY>                +---+    +---+

MY> IP*: asterisk is attached to distinguish IP* from encapsulating IP.
MY> MIP-tun: Mobile-IP tunnel (IP-in-IP or GRE or Minimal) from HA to FA (PDSN).
MY> RLP: Radio Link Protocol
MY> Link Layers and below are not shown (except RLP).

MY> (5) This draft only covers the following part.

MY> [MN]      [  RNN   ]    [   PDSN    ]

MY> +----+                  +---+
MY> |any |                  |any|
MY> +----+                  +---+
MY> |PPP |                  |PPP|
MY> +----+    +----+---+    +---+
MY> |RLP |    |RLP |GRE|    |GRE|
MY> +----+    +----+---+    +---+
MY>                |R-P|    |R-P|
MY>                +---+    +---+
MY>                | IP|    | IP|
MY>                +---+    +---+

MY> any: any protocol that can be carried over PPP.

MY> -- masa

MY> ------