Internet Draft SH.Kwon
Intended status: Experimental SJ.Koh
Expires: February 2010 Kyoung-pook National University
August 25, 2009
QMIP: Query-based Mobile IP
draft-kwon-qmipv4-00.txt
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Abstract
Mobile IP (MIP) suffers from the so-called triangular routing problem.
Moreover, MIP Home Agent (HA) tends to undergo severe data traffic
load, since it should deliver all the data packets toward mobile
nodes. This paper proposes a simple extension of MIP, called Query-
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based MIP (QMIP), in which the binding query to HA will be used to
get the care-of address of a mobile node and to deliver the
subsequent data packets over the optimized data path. The proposed
QMIP scheme can be applied to MIPv4 and Proxy MIPv6 as well.
Table of Contents
1. Introduction ................................................ 2
2. Conventions used in this document ............................ 3
3. Query-Based MIPv4 ........................................... 3
3.1. Data Transmission with Binding Query .................... 3
3.2. Comparison with MIPv4 ................................... 4
3.3. New Message for QMIPv4 .................................. 6
3.4. Consider of Query-Based Proxy MIPv6 ..................... 7
4. Security Considerations ...................................... 8
5. IANA Considerations ......................................... 8
6. Conclusions ................................................. 8
7. References .................................................. 8
7.1. Normative References .................................... 8
7.2. Informative References .................................. 8
8. Acknowledgments ............................................. 8
1. Introduction
The Mobile IP (MIP) was designed to support IP mobility [2]. However,
it suffers from the well-known 'triangular routing' problem, in which
Correspondent Node (CN) should transmit data packets to Mobile Node
(MN) via Home Agent (HA) over a non-optimized data path, until the
route optimization is additionally performed between CN and MN.
Another crucial concern of MIP is the excessive data traffic load at
HA, since all the data packets from CNs toward MNs should be
delivered by way of HA. Such overhead at HA will become much severe,
as the number of MNs increases in the network.
This paper proposes a simple extension of MIPv4, called Query-based
MIPv4 (QMIPv4), in which the Access Router (AR) attached to CN will
perform the binding query to HA, so as to get the Care-of Address
(CoA) of MN and to deliver all the subsequent data packets over the
optimized data path. For this purpose, we define the two new
messages: Binding Query Request and Binding Query Reply.
The proposed QMIP scheme can also be applied to the Proxy MIPv6
(PMIPv6) [3], rather than MIPv6 [4], since PMIPv6 has the similar
structure with MIPv4. We will first present QMIPv4, and then discuss
Query-based PMIPv6.
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2. Conventions used in this document
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [1].
3. Query-Based MIPv4
3.1. Data Transmission with Binding Query
We consider a simple network model for QMIPv4, as depicted in Fig. 1.
In the figure, MN performs the MIPv4 registration (or binding update),
and then CN tries to communicate with MN. The AR attached to CN acts
as a normal router with its own Query Cache (QC) table. This QC table
will be referred to by AR to identify the CoA of MN. Note that this
AR may also function as a Foreign Agent (FA) in the network.
Now, CN transmits data packets to MN over Home Address (HoA) of MN.
On reception of the first data packet destined to MN, the AR will
first look for CoA of MN in its QC table. If the corresponding CoA is
found in the table (we call it Cache Hit), AR will deliver the data
packet directly to MN by using the IP-in-IP tunneling. Otherwise, if
the CoA is not found (we call it Cache Miss), the AR will send a
Binding Query Request message to HA so as to get the CoA. Then, HA
responds with a Binding Query Reply message (containing CoA of MN) to
AR. The resulting information of mapping between HoA and CoA of MN
will be recorded into the QC table of AR, which will be referred to
by AR in the subsequent data transmissions to MN.
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+--+
|HA|
+--+
// \\
Binding Query // \\Binding Update
// \\
// \\
+--+ +--+ +--+ +--+
|CN| <=====> |AR| <====> |FA| <=====> |MN|
+--+ +--+ +--+ +--+
+-----+
|Query|
|Cache|
+-----+
AR: Access Router // Control Signal
FA: Foreign Agent <=> User Data Transport
CN: Correspondent Node
MN: Mobile Node
Figure 1 Network model for QMIPv4
3.2. Comparison with MIPv4
Fig. 2 compares the information flows of MIPv4 and QMIPv4.
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+--+ +--+ +--+ +--+ +--+
|CN| |AR| |HA| |FA| |MN|
+--+ +--+ +--+ +--+ +--+
| | | MIP Binding Update |
| | | <-------> | <-------> |
| |Initial Data Transport | |
|=========> |=========> |=========> |=========> |
| | | | |
|<========= |<===================== |<========= |
| | | | |
| | . | . | |
| | . | . | |
| | | | |
| |MIP Route Optimization | |
| |<--------------------> | |
| | | | |
| | Data Transport after | |
| | Route Optimization | |
|<========> |<====================> |<========> |
| | | | |
(a)MIPv4
+--+ +--+ +--+ +--+ +--+
|CN| |AR| |HA| |FA| |MN|
+--+ +--+ +--+ +--+ +--+
| | | MIP Binding Update |
| | | <-------> | <-------> |
|Cache Miss |QMIP Bind- | | |
| \|ing Query | | |
|=========> |<--------> | | |
| | Data Transport | |
| |=====================> |=========> |
| Cache Hit | | | |
| \| | | |
|<========> |<====================> |<========> |
| | | | |
(b)QMIPv4
Figure 2 Information flows of MIPv4 and QMIPv4
In MIPv4, MN will perform the registration with HA. All the data
packets transmitted by CN will be forwarded to HA and delivered by HA
to MN using the IP-in-IP tunneling, whereas MN will transmit its data
packets directly to CN, and hence the triangular routing occurs. Just
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after the route optimization, CN can use the optimized path for data
delivery to MN.
The QMIPv4 is the same with MIPv4, other than the binding query
operation with HA. When the first data packet arrives from CN, AR
will search for the corresponding CoA of MN in its QC table. In case
of Cache Hit that the CoA is found in the table, AR can transmit the
data packet directly to MN over the optimized path. However, in case
of Cache Miss, AR should perform the binding query to HA. After this,
all the subsequent data packets will be delivered to MN over the
optimized route, without further binding query operations.
Note that in MIPv4 the data transport between MN and CN will be done
over the optimized route, just after the route optimization is
completed, whereas the proposed QMIPv4 can intrinsically realize the
route optimization with a single binding query operation. Moreover,
in QMIPv4, Cache Hit may occur even for the first data packet of CN
(i.e., the binding query operation can be omitted), if another CN in
the same AR region is already communicating with the identical MN at
that time.
With the data transport over the optimized path, QMIPv4 can reduce
the transmission delays of data packets, compared to MIPv4. In
addition, QMIPv4 can avoid the problem of the excessive data traffic
load at HA, since the data transmission to MN will be performed by
the concerned AR, instead of HA, in the distributed manner.
3.3. New Message for QMIPv4
To support the QMIPv4, the two messages need to be newly defined:
Binding Query Request (from AR to HA) and Binding Query Reply (from
HA to AR). These messages can be defined in the similar format with
the MIP registration request/reply messages, as shown in Fig. 3.
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+----------+----------+-------------------+
| Type | Code | Lifetime |
+-----------------------------------------+
| Home Address |
+-----------------------------------------+
| Home Agent |
+-----------------------------------------+
| |
| Identification |
| |
+-----------------------------------------+
| Extensions |
+-----------------------------------------+
(a)Binding Query Request
+----------+----------+-------------------+
| Type | Code | Lifetime |
+-----------------------------------------+
| Home Address |
+-----------------------------------------+
| Home Agent |
+-----------------------------------------+
| Care-of Address |
+-----------------------------------------+
| |
| Identification |
| |
+-----------------------------------------+
| Extensions |
+-----------------------------------------+
(b)Binding Query Reply
Figure 3 Add a caption as here.
As shown in the figure, the Binding Query Request message contains
the information on HA and HoA of MN, whereas the Binding Query Reply
message additionally includes CoA of MN. The specific types of
messages are for further study.
3.4. Consider of Query-Based Proxy MIPv6
The Query-based MIP scheme can also be applied to the Proxy MIPv6. In
this case, the PMIPv6 Mobile Access Gateway will function as the
QMIPv4 AR and/or FA, and the PMIPv6 Localized Mobility Agent acts as
the QMIPv4 HA. In addition, the PMIPv6 Proxy Binding Update messages
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may need to be extended to support the binding query operation.
Details of the Query-based PMIPv6 are for further study.
4. Security Considerations
To be continue.
5. IANA Considerations
This specification has no actions for IANA.
6. Conclusions
This paper presents the Query-based MIP scheme that uses the binding
query to HA so as to get the optimized data path. The proposed QMIP
scheme can be applied to both MIPv4 and PMIPv6. In QMIP, we can
achieve much smaller transmission delay of data packets than MIP in
the usual case. Moreover, the QMIP is helpful to avoid the excessive
data traffic load at HA, since the data transmission to MN will be
performed by AR in the network, instead of HA.
7. References
7.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[2] IETF RFC 3344, IP Mobility Support for IPv4, August 2002
[3] IETF RFC 5213, Proxy Mobile IPv6, August 2008
[4] IETF RFC 3775, Mobility Support in IPv6, June 2004
[5] IETF RFC 4988, Mobile IPv4 Fast Handovers, October 2007.
8. Acknowledgments
Thanks goes to Hee Young Jung who have made insightful comments with
respect to interworking and careful review.
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Soon Hong Kwon
Kyoung-pook National University
Email: K.soonhong@gmail.com
Seok Joo Koh
Kyoung-pook National University
Email: sjkoh@knu.ac.kr
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