Internet-Draft Route Optimization for MN based on PD October 2003
Individual Submission
Internet Draft Kyeong-Jin Lee
Jaehoon Paul Jeong
Jung-Soo Park
Hyoung-Jun Kim
<draft-leekj-nemo-ro-pd-01.txt> ETRI
Expires: April 2004 4 October 2003
Route Optimization for Mobile Nodes in Mobile Network
based on Prefix Delegation
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
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Abstract
This document describes how to support Route Optimization for Mobile
Nodes in IPv6 Mobile Network. The support is provided by Prefix
Delegation. Mobile Router gets a prefix from an access router using
Prefix Delegation protocol and advertises the delegated prefix to its
subnet. Each Mobile Nodes makes its care-of address from the prefix
and performs binding update. It allows the Mobile Nodes to
communicate with Correspondent Nodes directly, avoiding ingress
filtering.
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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 [2].
Table of Contents
1. Terminology and Abbreviation..................................2
2. Introduction..................................................2
3. Protocol Overview.............................................3
4. Neighbor Discovery extension : Delegated Prefix option format.6
5. Mobile IPv6 extension : Process of Delegated Prefix option....7
6. Handover Considerations.......................................7
7. Security Considerations.......................................7
8. Consideration for Optimization of DNS Name Resolution.........7
9. Applicability Statements......................................7
10. References....................................................8
11. Authors' Addresses............................................8
1. Terminology and Abbreviation
This document uses the terminology and abbreviation of [2]-[4] on the
assumption that the reader is familiar with Mobile IPv6 and NEMO
terminology. In addition, the following term is used:
Delegated Prefix (DP)
A prefix assigned to a site by a provider, from which the site
may derive link prefixes [5].
2. Introduction
NEMO Basic Support is to preserve session continuity using
bidirectional tunnel between Mobile Router (MR) and MR's HA. The
support is reasonable for small-scale mobile network because MR MUST
encapsulate and decapsulate all packets for Mobile Network Nodes.
Specially, outbound packets MUST be tunneled in order to pass ingress
filtering.
The purpose of this document is to enable MNs behind the MR to
perform Mobile IPv6 Route Optimization. This can reduce the overhead
on MR because MR considers the packets of Local Fixed Nodes in the
bidirectional tunnel between MR and HA.
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When MR detects its movement, it runs Prefix Delegation(PD) protocol
such as APD, RA-PD and DHCP v6 described in [5]-[7] respectively. If
MRs become placed in multiple levels, the mobile network has
hierarchical architecture. Most of the current PD protocols are
designed for leaf network. How to extend PD protocol for hierarchical
IPv6 network is outside the scope of this specification.
Even when every AR on visited network does not support PD, there
SHOULD be no problem in the communication between MN and CN. If this
mechanism is disabled, all the Mobile Network Nodes (MNNs)
communicate with CN by NEMO Basic Support. Therefore, it can provide
Route Optimization for mobile nodes within mobile network according
as the access network allows PD.
This specification defines a new Neighbor Discovery Protocol option
and modifies the operation of MR and MN to support route optimization.
Fixed router in mobile network is not considered in this
specification.
3. Protocol Overview
This document assumes that all AR and MR support PD. Otherwise, only
NEMO Basic Support [8]-[9] is provided to preserve session continuity
and Route Optimization is disabled.
Figure 1 shows a topology before two MRs move from home link to
foreign link. When the MR1 and MR2 are at home link, each MR uses
1:1:: and 2:1:: respectively as its own mobile network prefix.
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+---+
|CN |
+-+-+
|
+------+ +--+-----+ +------+
|HA-MR1|-----------|Internet|----------------|HA-MR2|
+---+--+ +--+-----+ +----+-+
|1:: | 2:: |
+-+-+1 +--+-+ +-+-+3
|MR1| | AR | |MR2|
+-+-+2 +--+-+ +-+-+4
|1:1:: | 3:: 2:1:: |
--+---+--+------+- ----+--- ---+---+--+--
| | | | |
+-+-+5 +-+-+6 +-+-+7 +-+-+8 +-+-+9
|LMN| |VMN| |LFN| |LMN| |VMN|
+---+ +---+ +---+ +---+ +---+
Figure 1. Mobile router at home link
Figure 2 shows a topology after two MRs move from home link to
foreign link and each MR performs PD. First, MR1 detects movement and
gets a prefix (3:1::) from AR. MR1 advertises the DP to its subnet by
sending RA message with Delegated Prefix option. And then, MR2 moves
to MR1's network. MR2 gets prefix (3:1:1::) from MR1 and advertises
the prefix to its subnet.
When each MN receives RA message with Delegated Prefix option, it
processes the DP option preferentially: make CoA from the prefix and
performs binding updates to HA and CN. In figure 2, CoA1 is used as a
primary CoA, which is made from DP. This process is transparent to
LFNs.
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+---+
|CN |
+-+-+
|
+------+ +--+-----+ +------+
|HA-MR1|-----------|Internet|----------------|HA-MR2|
+---+--+ +--+-----+ +----+-+
|1:: | 2:: |
+--+-+
| AR |
+--+-+
| 3::
--+----+------
|
+-+-+ HoA 1::1, CoA 3::1
|MR1| Delegated Prefix(DP) = 3:1::
+-+-+ Mobile Network Prefix(MNP) = 1:1::
|
--+---+--+------+--------+------
| | | |
+-+-+ +-+-+ +-+-+ +-+-+ HoA 2::3
|LMN| |VMN| |LFN| |MR2| CoA1 3:1::3
+---+ +---+ +---+ +-+-+ CoA2 1:1::3
CoA1 3:1::5 3:1::6 | DP = 3:1:1::
CoA2 1:1::6 ---+---+--+-- MNP = 2:1::
| |
+-+-+ +-+-+
|LMN| |VMN|
+-+-+ +-+-+
CoA1 3:1:1::8 3:1:1::9
CoA2 2:1::9
Figure 2. Prefix Delegation for Route Optimization
After the PD, the routing table of routers is updated by routing
protocol. It is possible because each router has information about
delegated prefix.
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4. Neighbor Discovery extension : Delegated Prefix option format
This specification defines a new option, the Delegated Prefix option,
for the Neighbor Discovery protocol of IPv6. The option format is
shown in Figure 2.
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| Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ Prefix +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2. Delegated Prefix Option Format for Route Optimization
Fields:
Type XXX [TBD: IANA]
Prefix Delegated Prefix. The Prefix Length field contains
the number of valid leading bits in the prefix. The
bits in the prefix after the prefix length are
reserved and MUST be initialized to zero by the
sender and ignored by the receiver
The Delegated Prefix option provides mobile nodes with on-link prefix
of access network and prefix for address autoconfiguration of CoA.
The Delegated Prefix option appears in Router Advertisement packets
and MUST be silently ignored for other messages.
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5. Mobile IPv6 extension : Process of Delegated Prefix option
MN scans all options in received router advertisement message. To
initiate Route Optimization MN operation MUST be extended as follows:
(1)Process the new RA option, Delegated Prefix option: MN forms CoA
using the prefix.
(2)Use the CoA as primary CoA.
MN performs registration procedure according to the Mobile IPv6
protocol. Even if LMN is on home link, it SHOULD make new CoA using
the DP and SHOULD perform binding updates to HA and CN. In this case,
deregistration SHOULD NOT be performed.
There is no change of HA and CN operations.
6. Handover Considerations
When a MR moves into another AR and detects movement, it SHOULD NOT
return prefix delegated from the old AR immediately. It takes some
time to find out whether the new AR supports PD or not. Moreover, MR
can fail in PD for several reasons. Therefore, some considerations
are needed for smooth handover.
7. Security Considerations
Because the mechanism described in this document needs to exchange PD
message between a MR and its AR, AAA MAY be used to authenticate MR.
8. Consideration for Optimization of DNS Name Resolution
The optimization of DNS name resolution is possible if mobile router
announces the address of local recursive DNS server as well as prefix
information through RA message. The DNS server can exist either
within mobile network or within access network. The address of
recursive DNS server is delivered to mobile nodes through Recursive
DNS Server option, one of RA options [10].
9. Applicability Statements
Proposed mechanism in this draft is applicable to large, hierarchical
and stable mobile network such as train or airplane because it takes
some time to configure and update new CoA by prefix delegation
protocol. Those mobile networks do not change its topology frequently
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so it reduces time to be consumed for prefix delegation whenever the
topology changes in the mobile network.
10. References
[1] Bradner, S., "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996.
[2] Thierry Ernst, "Network Mobility Support Terminology", draft-
ietf-nemo-terminology-00.txt, May 2003.
[3] D. Johnson, C. Perkins and J. Arkko, "Mobility Support in IPv6",
draft-ietf-mobileip-ipv6-22.txt, May 2003.
[4] J. Manner and M. Kojo, "Mobility Related Terminology", draft-
ietf-seamoby-mobility-terminology-04.txt, Oct 2003.
[5] Nathan Lutchansky, "IPv6 Router Advertisement Prefix Delegation
Option", draft-lutchann-ipv6-delegate-option-00.txt, Aug 2002.
[6] B. Haberman, "Automatic Prefix Delegation Protocol for Internet
Protocol Version 6 (IPv6)", draft-haberman-ipngwg-auto-prefix-
02.txt, Aug 2002.
[7] O. Troan and R. Droms, "IPv6 Prefix Options for DHCPv6", draft-
troan-dhcpv6-opt-prefix-delegation-00.txt, Aug 2002.
[8] T.J. Kniveton, Jari T. Malinen, Vijay Devarapalli and Charles E.
Perkins, "Mobile Router Tunneling Protocol", draft-kniveton-
mobrtr-03.txt, May 2003.
[9] Ryuji wakikawa, Keisuke Uehara, Koshiro Mitsuya and Thierry Ernst,
"Basic Network Mobility Support", draft-wakikawa-nemo-basic-
00.txt, Feb 2003.
[10] Jaehoon Jeong, Soohong D. Park, Luc Beloeil and Syam Madanapalli,
"IPv6 DNS Discovery based on Router Advertisement", draft-jeong-
dnsop-ipv6-dns-discovery-00.txt, July 2003.
11. Authors' Addresses
Kyeong-Jin Lee
ETRI / PEC
161 Gajong-Dong, Yusong-Gu
Daejon 305-350
Korea
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Internet-Draft Route Optimization for MN based on PD October 2003
Phone: +82 42 860 6484
EMail: leekj@etri.re.kr
Jaehoon Paul Jeong
ETRI / PEC
161 Gajong-Dong, Yusong-Gu
Daejon 305-350
Korea
Phone: +82 42 860 1664
EMail: paul@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
Hyoung-Jun Kim
ETRI / PEC
161 Gajong-Dong, Yusong-Gu
Daejon 305-350
Korea
Phone: +82 42 860 6576
EMail: khj@etri.re.kr
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