One document matched: draft-hkang-nemo-ro-tlmr-00.txt
Route Optimization for Mobile Network June 2003
Individual Submission
Internet Draft Hyunsik Kang
Document: draft-hkang-nemo-ro-tlmr-00.txt Keecheon Kim
Sunyoung Han
Konkuk University
Kyeong-Jin Lee
Jung-Soo Park
ETRI
Expires: December 20023 June 2003
Route Optimization for Mobile Network by Using Bi-directional
Between Home Agent and Top Level Mobile Router
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 except that the right to
produce derivative works is not granted [1].
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
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Abstract
This document shows how to route optimization by using bi-directional
tunnel between home agent and top level mobile router. A packet will
be transmitted directly from the home link of the mobile node to top
level mobile router of the correspondent node through this tunnel.
Conventions used in this document
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.
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Route Optimization for Mobile Network June 2003
Table of Contents
1. Introduction...................................................2
2. Overview.......................................................2
3. Mobile Router extension : mobile router of mobile subnetwork...3
4. Mobile Router extension : Top level mobile router..............4
5. Home agent extension for Mobile Router.........................4
6. New RA message and mobility option.............................4
6.1 RA message with TLMR option................................4
6.2 New mobility option........................................5
7. Procedure of Route Optimization................................6
7.1 Receiving RA message from TLMR.............................6
7.2 Registration to TLMR and binding update to home agent with
TLMR address...................................................7
7.3 Delivery of Data Packets...................................7
7.3.1 CN transmit to MN (or Fixed Node in MR)7
7.3.2 MN (or Fixed Node in MR) transmits to CN 7
Security Considerations...........................................8
References........................................................8
Author's Addresses................................................8
1. Introduction
The basic support of mobile network (NEMO) enables mobile network
nodes and correspondent nodes to communicate through bi-directional
tunnels. However, using MIPv6 for mobile network will introduce a
problem of dog-leg routing. In order to communicate from foreign
networks with mobile nodes, packets are usually transmitted via the
home link of the mobile node. Dog-leg routing may cause a
transmission latency, this subsequently causes the difficulty for a
real time service and the delay in binding update. This document
specifies how we can optimize the routing in NEMO [2]-[4].
2. Overview
A possible solution to routing optimization is to make tunnels
between top level mobile router of NEMO and home agent of each mobile
router. When a mobile node detects an access to a foreign network, a
mobile router does binding update to home agent. At this time, mobile
router detects IP address of the top level mobile router(TLMR) by
router advertisement extension message(see figure 1.). And then, the
mobile router registers to TLMR and notifies address of TLMR to its
own home agent. When TLMR receives a registration message from the
mobile router, it detects a relationship between mobile router and
its access router. From this information, TLMR forms a mobile
sub-network topology table. Using this table, TLMR creats a tunnel to
each mobile router, if necessary, to communicate with mobile router.
This tunnel is used by the encapsulated packets to be transmitted
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Route Optimization for Mobile Network June 2003
between TLMR and mobile router. (see Section 7.4)
+-----+
|TLMR |
RA(TMLR) |+--+--+
V |
----------+---------------+-------------+----------- Link1
| |
+-+-+ +-+-+
|MR1| |MR2|
RA(MR1+TLMR) | +-+-+ RA(MR2+TLMR)| +-+-+
V | V |
---+-----+-----+--- Link2 ---+------+-----+--- Link3
| | | |
+-+-+ +-+-+ +-+-+ +-+-+
|MN1| |FN1| |MN2| |MR3|RA(MR3+TLMR)
+---+ +---+ +---+ +---+ |
| V
Link4 ---+-----+-----+---
| |
+-+-+ +-+-+
|MN3| |FN2|
+-+-+ +-+-+
Figure 1. Routing advertisement message extension for route optimize
***********
+///////////+ |#########|###########+ FN2
CN ----------------|===========+=+=========+===========+--------
+///////////+ |#########|###########+
*********** MR3
MR3_HA TLMR MR2
------- : original packet
+=====+ : tunneling between HA of MR3 and MR3
+/////+ : tunneling between HA of MR3 and TLMR
+#####+ : tunneling between TLMR and MR3
+*****+ : tunneling between TLMR and MR2
Figure 2. all tunneling model of RO solution
3. Mobile Router extension : mobile router of mobile subnetwork
Mobile router MUST relay extended router advertisement message of
TLMR that has been transmitted from its parent mobile router to its
child mobile router. If a mobile router receives an extended router
advertisement message of TLMR, it MUST notify the TLMR's address to
its own home agent to set up a direct tunnel between the home agent
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Route Optimization for Mobile Network June 2003
and TLMR. The mobile router registers its address and the address of
its parent router to TLMR to set up a tunnel between TLMR and mobile
router.
When a mobile router receives a packet from its children nodes, if
the packet's destination address is TLMR, then the mobile router does
encapsulation to make the destination address to be TLMR, not its
home agent. This makes a direct communication between mobile router
and TLMR. Therefore, this packet doesn't have to pass the home agent
of the parent mobile router.
4. Mobile Router extension : Top level mobile router
If the mobile router doesn't receive an extended router advertisement
with TLMR option, it becomes a TLMR. The TLMR MUST advertise that it
is TLMR by an extentded router advertisement message with TLMR option
(see Section 6.1). When a mobile router receives this message, it
requests a registration to TLMR by sending registration request
message. This message includes its address and the address of the
access router(parent router). When the TLMR recieves a registration
request message, if it accepts the registration, it determines the
path to mobile router from the addresses in this message.
Based on this routing information, TLMR decides how to encapsulate
the packet to the mobile router or a home agent of a mobile router.
5. Home agent extension for Mobile Router
The home agent of mobile router SHOULD bind the CoA of the mobile
router and address of TLMR of the mobile router from new binding
update message which has the TLMR address option. The home agent
SHULD adds TLMR field to its own binding table. This field is used
for encapsulating a pakcet to TLMR. When a home agent receives a
packet to the mobile router, it SHOULD encapsulate the packet to send
to the CoA of the mobile router. But, for a route optimization, the
home agent SHOULD perform one more encapsulation to have its
destination address is TLMR. Similarly, when a home agent receives a
packet from TLMR, it can find an original packet encapsulated by a
mobile router through decapsulating the packet encapsulated by TLMR
6. New RA message and mobility option
This approach needs some new message formats or options such as
router advertisement message, registration request message to TLMR,
and binding request message to home agent with TLMR address for route
optimization [5]-[8].
6.1 RA message with TLMR option
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The router advertisement messages with TLMR option is needed by a
mobile router to create a bi-directional tunnel between TLMR and the
home agent of mobile router.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Prefix Length |L|A|R|T|P|Res 1|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Field:
T 1-bit TLMR flag. When set, it indicates that the
message contains the address of the TLMR
P 1-bit parent mobile router flag. When set, it
indicates that this message contains the CoA of
the parent mobile router. The CoA of the parent mobile
router is used for tunneling between TLMR and the
parent mobile router.
T flag and P flag SHOULD not be set at the same time.
Address This address is an address of the TLMR or parent
mobile router.
Figure 3. Modified Prefix Information Option Format for RO
When T flag is set, it indicates that this message includes the
address of the TLMR. This option is used by a mobile router to send
binding update to home agent and registration message to TLMR.
6.2 New mobility option
A modified binding update message is used when a mobile router
registers to TLMR and updates its binding to home agent. The TLMR
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Route Optimization for Mobile Network June 2003
determines the path to the mobile router from the address in this
message.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 6 | Option Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Address +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Field:
Address The address is an address of the parent mobile router
of the mobile router or CoA of TLMR. When this message
is used for registering to TLMR, this field contains
the CoA of parent mobile router. When TLMR needs to
send a packet, TLMR creats a tunnel to this address.
On the other hand, when this message is used for
sending binding update to home agent, this field
contains an address of TLMR. The home agent SHOULD
create a bi-directional tunnel to TLMR.
Figure 4. Modified binding update message
<Text for this section>
7. Procedure of Route Optimization
7.1 Receiving RA message from TLMR
A mobile router waits for an extended router advertisement message.
If the mobile router receives an extended router advertisement
message, it does binding update to TLMR and home agent with modified
binding update message. The mobile router MUST relay this message to
its child mobile router.
If the mobile router doesn't receive an extended router advertisement
message, it means the router is TLMR. The mobile router becomes TLMR,
and it sends an extended router advertisement message with the
address of TLMR which is the address of mobile router itself.
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7.2 Registration to TLMR and binding update to home agent with TLMR
address
When the mobile router receives an extended router advertisement
message, it SHOULD register to TLMR and send binding update to its
home agent.
When TLMR receives a registration request message from a mobile
router, it makes a tunneling table to mobile router from this
message. The tunneling table is composed of mobile router and its
access router. When the home agent receives this binding update
message, it creates a bi-directional tunnel between the home agent
and TLMR, which will be used for direct communication without dog-leg
routing.
7.3 Delivery of Data Packets
7.3.1 CN transmit to MN (or Fixed Node in MR)
A correspondent node sends a packet to a node in mobile router, and
this packet goes to the home network of mobile router. The home agent
intercepts this packet, and encapsulates it to send to a mobile
router. In order to communicate with a mobile router directly, the
home agent encapsulates again to send the packet to TLMR. When TLMR
receives this packet, it decapsulates the packet. TLMR finds the
destination address to determine the path to the mobile router by
using the tunneling table. In order to send to a mobile router, TLMR
does encapsulation for ecah mobile routers that are between TLMR and
destination mobile router. In this way, TLMR sends a pakcet to a
mobile router. When a mobile router receives a packet, it first
decapsulates the packet encapsulated by TLMR, and it does one more
decapsulation encapsulated by its home agent. This packet will be
sent to the destination node.
7.3.2 MN (or Fixed Node in MR) transmits to CN
When a node in mobile network sends a packet to CN, this packet is
encapsulated by a mobile router to be sent to the home agent of
mobile router. The mobile router encapsulates the packet again to
directly communicate with TLMR. This packet goes to the parent mobile
router, the parent mobile router does encapsulation again for direct
communication with TLMR. Likewise, this packet is encapsulated by
each mobile router located between TLMR and mobile router. When this
packet arrives on TLMR, TLMR decapsulates all the encapsulation
headers made by intermediate mobile routers except for the
encapsulation made by the end-point mobile router. And then, TLMR
encapsulates the packet to send to the home agent of mobile router.
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When the mobile router receives this packet, it decapsulates the
packet ecapsulated by the TLMR and end-point mobile router. The
packet decapsulated by home agent is the original packet that has
been sent to the correspondent node.
Security Considerations
The route optimization in this document does not add any other
security problems to the NEMO or Mobile IPv6.
References
[1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996.
[2] T. Narten, E. Nordmark and W. Simpson, "Neighbour Discovery for
IP version 6", RFC 2461.
[3] Dave Thaler and Chistian Huitema, "Multi-link Subnet Support in
IPv6", draft-ietf-ipv6-multilink-subnets-00.txt, June 2002.
[4] Thierry Ernst, "Network Mobility Support Terminology", draft-
ietf-nemo-terminology-00.txt, May 2003.
[5] D. Johnson, C. Perkins and J. Arkko, "Mobility Support in IPv6",
draft-ietf-mobileip-ipv6-22.txt, May 2003.
[6] Ryuji Wakikawa, Keisuke Uehara, Koshiro Mitsuya, Thierry Ernst,
"Basic Network Mobility Support", draft-wakikawa-nemo-basic-
00.txt, Feb 2003.
[7] Thierry Ernst, "Network Mobility Support Goals and Requirements",
draft-ietf-nemo-requirements-01.txt, May 2003
[8] Thierry Ernst, Hong-Yon Lach, "Network Mobility Support
Terminology", draft-ietf-nemo-terminology-00.txt, May 2003
Author's Addresses
Hyunsik Kang
Department of Computer Science & Engineering, Konkuk University
Whayangdong 1, Kwangjin-ku
Seoul 143-701
Korea
Phone: +82 2 450 3518
EMail: bigbomb@konkuk.ac.kr
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Keecheon Kim
Department of Computer Science & Engineering, Konkuk University
Whayangdong 1, Kwangjin-ku
Seoul 143-701
Korea
Phone: +82 2 450 3518
EMail: kckim@konkuk.ac.kr
Sunyoung Han
Department of Computer Science & Engineering, Konkuk University
Whayangdong 1, Kwangjin-ku
Seoul 143-701
Korea
Phone: +82 2 450 3537
EMail: syhan@cclab.konkuk.ac.kr
Kyeong-Jin Lee
ETRI / PEC
161 Gajong-Dong, Yusong-Gu
Daejon 305-350
Korea
Phone: +82 42 860 6484
EMail: leekj@etri.re.kr
Jung-Soo Park
ETRI / PEC
161 Gajong-Dong, Yusong-Gu
Daejon 305-350
Korea
Phone: +82 42 860 6514
EMail: pjs@etri.re.kr
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