NETEXT Working Group Yujin Lim
Internet Draft University of Suwon
Expires: April 25, 2010 Sanghyun Ahn
University of Seoul
Jungsoo Park
HyeongJun Kim
ETRI/SRC
October 26, 2009
LMA Handovers for Proxy Mobile IPv6
draft-lim-netext-lma-handover-01.txt
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and restrictions with respect to this document.
Abstract
This document describes a mechanism for context transfer between
Local Mobility Anchors (LMAs) in a large Proxy MIPv6 domain to
provide the IP ongoing session continuity of mobile nodes. In order
to enhance the performance of the LMA handover, a bi-directional
tunnel between a previous LMA and a new target LMA is established.
Table of Contents
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. LMA Handover for PMIPv6 Overview . . . . . . . . . . . . . . . 4
4.1 Extended Policy Profile . . . . . . . . . . . . . . . . . . 5
4.2 Protocol Operation . . . . . . . . . . . . . . . . . . . . 5
5. Other Considerations . . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . . . 7
Appendix A. Routing State Update . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9
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1. Requirements notation
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 [RFC2119].
2. Introduction
The Proxy Mobile IPv6 (PMIPv6) [RFC5213] domain refers to the network
where the mobility management of a Mobile Node (MN) is handled using
the Proxy Mobile IPv6 protocol. The Proxy Mobile IPv6 domain includes
Local Mobility Anchors (LMAs) and Mobile Access Gateways (MAGs).
This document describes a mechanism to provide the ongoing session
continuity to a MN during the handover from one LMA to another LMA
in a Proxy Mobile IPv6 domain.
This specification addresses the following problems:
o Who and when to trigger the LMA handover.
o Who and how to select a new target LMA.
o How to transfer the context information between LMAs.
o Table updates of network entities.
o Other considerations.
When a previous MAG and a new MAG share the same LMA, the previous
MAG transfers the context information of a MN to the new MAG via the
bi-directional tunnel between them by using a MAG handover mechanism,
such as the Fast Handovers for Proxy Mobile IPv6 (PFMIPv6) [PFMIPv6]
protocol. This document provides a mechanism for transferring the
context information of a MN from a Previous LMA (PLMA) to a new LMA
(NLMA) by establishing a bi-directional tunnel.
3. Terminology
This document reuses the terminology from [RFC5213] and [RFC3775].
The following terms and abbreviations are additionally used in this
document.
Boundary Mobile Access Gateway (bMAG):
The MAG that has connections from more than one LMA. The bMAG
decides when it triggers the LMA handover and requests a previous
LMA to initiate the LMA handover.
Previous Local Mobility Anchor (PLMA):
It is the topological anchor point that manages the MN's binding
state before the LMA handover. The PLMA initiates to hand over the
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IP mobility session and forwards the context information of the
MN to the new target LMA.
New Local Mobility Anchor (NLMA):
The LMA that receives the context information of the MN from the
PLMA and maintains the MN's binding state after the LMA handover.
4. LMA Handovers for PMIPv6 Overview
To deliver the context information of the MN from the PLMA to the
NLMA efficiently, a LMA Handover Request (LMA_HO_Req) and a LMA
Handover Response (LMA_HO_Resp) messages are exchanged between the
bMAG and the PLMA. In the messages, MN'Identifier (MN ID), MN
Link-layer Identifier (MN-LL-ID) and MN's Home Network Prefix
(MN-HNP) are included.
The reference network is illustrated in Figure 1.
+----+ +----+
|PLMA| |NLMA|
+----+ +----+
| |
| |
//\\ //\\
// \\ // \\
// \\ // \\
+---- // -----\\------------- //------\\----+
( // \\ IPv4/IPv6 // \\ )
( // \\ Network // \\ )
+--// -----------\\--------//------------\\-+
// \\ // \\
// \\ // \\
// \\ // \\
| | |
+..........+ +..........+ +..........+
. +----+ . . +----+ . . +----+ .
. |MAG1| . . |bMAG| . . |MAG3| .
. +----+ . . +----+ . . +----+ .
. . . | . . .
. . . | . . .
. ------------> {MN} --------------> .
. . . . . .
+..........+ +..........+ +..........+
Figure 1: Reference network for the LMA handover
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4.1. Extended Policy Profile
A MN's policy profile is stored in a local or a remote policy store.
The mandatory fields of the policy profile are the MN ID and the LMA
Address (LMAA). In this document, the LMAA field includes the address
(NLMAA) of the LMA currently serving the MN. The optional fields of
the policy profile is extended with the PLMAA field to include the
address of the PLMA.
4.2. Protocol Operation
The sequence of events illustrating the LMA handover is shown in
Figure 2.
The detailed description is as follows:
(a) The MN detects a new link and reports the identifications of
itself (MN ID) and the access point (New AP ID) to which the MN
is most likely to move. The detection mechanism of a new subnet
link of a MN is specific to the access link between the MN and
the MAG and it is out of the scope of this document.
(b) The bMAG sends a LMA_HO_Req message to the PLMA to initiate the
LMA handover.
(c) The PLMA selects the NLMA and sends a LMA_HO_Init message with
the context information of the MN to the NLMA. The PLMA is
assumed to maintain the information on the other LMAs in the
same PMIPv6 domain, such as the message exchanges between LMAs,
the external information input and the reception of the
information from the AAA/Policy store. However, this is out of
the scope of this document.
(d) The NLMA received the LMA_HO_Init message creates a bind cache
entry (BCE) of the corresponding MN and, then, a bi-directional
tunnel is set up between the PLMA and the NLMA by sending
a LMA_HAck message to the PLMA.
(e) The PLMA notifies bMAG of the completion of the context transfer
regarding the MN from the PLMA to the NLMA by sending a
LMA_HO_Resp message to the bMAG.
(f) The bMAG initiates the tunnel setup between the bMAG and the
NLMA by sending a Proxy Binding Update (PBU) message to the
NLMA.
(g) The NLMA sends an Update message to the remote policy store to
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AAA
MN bMAG PLMA NLMA /Policy Store
| | | | |
| Report | | | |
(a) |-(MN ID,-->| | | |
| New AP ID)| | | |
| |LMA_HO_Req | | |
(b) | |--(MN ID)->| | |
| | |LMA_HO_Init| |
(c) | | |-(MN ID,-->| |
| | | MN-LL-ID,| |
| | | MN-HNP) | |
| | | | |
(d) | | |<-LMA_HAck-| |
| | | (MN ID) | |
| | | | |
| | |==Bi-Dir===| |
| | | Tunnel | |
| |LMA_HO_Resp| | |
(e) | |<-(MN ID)--| | |
| | | | |
(f) | |---------PBU---------->| |
| | | | Update |
(g) | | | |-(MN ID,-->|
| | | | NLMAA) |
| | | | |
| | | |Update_Ack |
(h) | | | |<-(MN ID)--|
| | | | |
(i) | |<--------PBA-----------| |
| | | | |
| |=====Bi-Dir Tunnel=====| |
| | | | |
(j) | | |==========>|=# |
|<==========|<========DL data=========# |
| | | | |
(k) |==========>|=========UL data======>| |
| | | | |
Figure 2: LMA handover for PMIPv6
inform the policy store of the fact that the NLMA is the new LMA
currently serving the MN.
(h) The remote policy store sends an Update_Ack message to the NLMA
in order to let the NLMA know that the LMAA field in the
policy profile of the MN is set to the NLMA.
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(i) The bi-directional tunnel between the bMAG and the NLMA is
completely established by the NLMA's sending a Proxy Binding
Acknowledgement (PBA) message to the bMAG.
(j) The data downloaded from the correspondent node (CN) arrives at
the PLMA which is the topological anchor point of the MN, and
the PLMA forwards the downloaded data to the NLMA through the
tunnel between them. Then, the NLMA sends the data to the MN via
the bMAG. For the efficiency of the data delivery, it is
possible to consider the route optimization additionally.
(k) The data uploaded from the MN to the CN are delivered to the CN
via the bMAG and the NLMA in that order.
5. Other Considerations
Security issues for this document follow those for PMIPv6 [RFC5213].
In PMIPv6, the MAG and LMA are assumed to share security
associations. This document also assumes that the LMAs that
participate in handover have adequate prior agreement and trust
relationship between each other.
6. References
6.1. Normative References
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3775] Johnson, D., "Mobility Support in IPv6", RFC 3775,
June 2004.
6.2. Informative References
[PFMIPv6] Yokota, H., Chowdhury, K., Koodli, R., Patil, B., and Xia,
F., "Fast Handovers for Proxy Mobile IPv6",
draft-ietf-mipshop-pfmipv6-09.txt, Sep. 2009.
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Appendix A. Routing State Update
The following section explains the routing state update for a MN on the
MAG. The below example identifies the routing state update for a MN,
MN1, with its local mobility anchors, the PLMA and the NLMA. After the
LMA handover, for all traffic from the MN1 to _ANY_DESTINATION_ route
via the interface tunnel1 toward the NLMA.
+==================================================================+
| Packet Source | Destination Address | Destination Interface |
+==================================================================+
| MAC_Address_MN1, | _ANY_DESTINATION_ | Tunnel0 |
| (IPv6 Prefix or |----------------------------------------------|
| Input Interface) | Locally Connected | Tunnel0 |
+------------------------------------------------------------------+
(a) before the LMA handover
+==================================================================+
| Packet Source | Destination Address | Destination Interface |
+==================================================================+
| MAC_Address_MN1, | _ANY_DESTINATION_ | Tunnel1 |
| (IPv6 Prefix or |----------------------------------------------|
| Input Interface) | Locally Connected | Tunnel1 |
+------------------------------------------------------------------+
(b) after the LMA handover
Example - Policy-Based Route Table
+==================================================================+
| Interface | Source Address | Destination Address | Encapsulation |
+==================================================================+
| Tunnel0 | Proxy-CoA | PLMAA | IPv6-in-IPv6 |
+------------------------------------------------------------------+
| Tunnel1 | Proxy-CoA | NLMAA | IPv6-in-IPv6 |
+------------------------------------------------------------------+
Example - Tunnel Interface Table
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Authors' Addresses
Yujin Lim
University of Suwon
San 2-2, Wau-ri, Bongdam-eup
Hwaseong-si, Gyeonggi-do, 445-743
Korea
Email: yujin@suwon.ac.kr
Sanghyun Ahn
University of Seoul
90, Cheonnong-dong, Tongdaemun-gu
Seoul 130-743
Korea
Email: ahn@uos.ac.kr
Jungsoo Park
ETRI/SRC
161 Gajeong-dong, Yuseong-gu
Daejeon 305-350
Korea
Email: pjs@etri.re.kr
HyeongJun Kim
ETRI/SRC
161 Gajeong-dong, Yuseong-gu
Daejeon 305-350
Korea
Email: khj@etri.re.kr
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