Internet DRAFT - draft-arita-netext-pnemo
draft-arita-netext-pnemo
Internet Draft Tetsuya Arita
<draft-arita-netext-pnemo-00.txt> Fumio Teraoka
Keio univ.
Expires April 2011 October 12, 2010
Proxy Network Mobility Protocol
<draft-arita-netext-pnemo-00.txt>
Status of this Memo
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Abstract
Proxy Mobile IPv6 (PMIPv6) provides the Internet connectivity to
Mobile Node in a PMIPv6 domain. Current PMIPv6 specification supports
only Host Mobility. In order to support a network mobility, this
document defines Proxy Mobility Protocol that provides and maintains
the connectivity for the Mobile Network Node (MNN) in the mobile
network (nemo). This document discusses the deployment consideration
of PNEMO and proposes the possible solution accordingly.
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Table of Contents
1. Introduction ....................................................3
2. Conventions and Terminology .....................................4
3. Proxy Network Mobility Protocol .................................4
3.1 Protocol Overview ............................................4
3.2 Nested Network ...............................................7
4. Local Mobility Anchor Operation ................................10
5. Mobile Access Gateway Operation ................................11
6. Mobile Router Operation ........................................13
7. References .....................................................14
7.1. Normative References .......................................14
1. Introduction
Network Mobility Basic Support (NEMO BS) [RFC-3963] was proposed to
support network mobility. Similar to Mobile IPv6 (MIPv6) [RFC-3775],
the Home Agent (HA) and the Mobile Router (MR) are important entities
in NEMO BS. The HA maintains the prefix of the mobile network (nemo)
and forwards packets to and from the nemo. The MR establishes a bi-
directional tunnel to the HA. However, NEMO BS has several problems.
If the nemo is nested, the header overhead increases because of
multiple tunnels. If the wireless link between the MR and the access
router (AR) is unstable after handover, the signaling messages such
as Binding Update (BU) might be lost.
Proxy Mobile IPv6 (PMIPv6) [RFC-5213] provides mobility to the Mobile
Node (MN) in the PMIPv6 domain. To achieve mobility in the PMIPv6
domain, the Local Mobility Anchor (LMA) and the Mobile Access Gateway
(MAG) are installed. The LMA serves as the HA in MIPv6. It manages
the binding between the LMA and the MAG to which the MN is attached.
The MAG sends the signaling messages to MN's LMA on behalf of the MN.
It establishes a bi-directional tunnel to the LMA. In PMIPv6, the
signaling messages are exchanged in the wired network. Even if the
wireless link between the MN and the MAG is unstable after handover,
the signaling messages between the MAG and the LMA are rarely lost.
This document defines a protocol called PNEMO that provides network-
based localized mobility to a mobile network. In PNEMO, the signaling
messages are exchanged between the MAG and the LMA, i.e., the MR does
not participate in the signaling procedure. PNEMO is an extension of
PMIPv6. The MR sends and receives the packets for the Visited Mobile
Node (VMN) and the Local Fixed Node (LFN). It also informs the state
of the nemo to the LMA and the MAG. As the LMA and the MAG manage the
location information of the VMN and the nested network, they can
forward the packets to the VMN and the nested network in the nemo.
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The MR has the NEMO State Table, which manages the location
information of the VMN and the nested network in its lower subnet.
2. Conventions and Terminology
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 [RFC-2119].
3. Proxy Network Mobility Protocol
3.1. Protocol Overview
This document defines the specification of a network-based mobility
management protocol for a mobile network (nemo), called Proxy Network
Mobility Protocol (PNEMO). It is an extension of Proxy Mobile IPv6.
The LMA and the MAG will keep track of nemo's movements, initiate the
mobility signaling, and set up the required routing state.
The entities in the NETLMM infrastructure are the LMA, the MAG and
the MR. The LMA is responsible for maintaining the reachability state
of the MR and the VMN. it allocates the prefixes for mobile nodes to
configure their address. The MR is allocated the Home Network Prefix
(HNP) and the Mobile Network Prefix (MNP). The VMN is allocated the
HNP. The LMA is the topological anchor point for these prefixes. The
MAG is the entity that performs the mobility management on behalf of
the MR and the VMN. It emulates the Home Link of the MR and the VMN.
It is responsible for detecting nemo's movements to and from the
access link and for initiating binding registrations to the LMA of
the MR's or the VMN's. The MAG itself manages its binding information
of the nemo. When the MAG receives packets destined to the nodes in
the nemo, it forwards the packets to the corresponding MR. A nemo
consists of a MR, VMNs and LFNs. The MR is the default router of the
nemo and the entity that manages the nested network. In the nested
nemo, the MR informs the configuration change in the nemo to the MAG.
The LFN in the nemo configures its address using the MNP advertised
by the MR.
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+-----+
| LMA |
+-----+
|<--LMAA
Tunnel-->//
+-------//---+
( // )<-- IPv6 Network
( // )
+----//------+
|
|<-Proxy-CoA
+-----+ ____MR-HNP
| MAG | /
+-----+-----{ MR }
| |
VMN-HNP-->| |<--LFN-MNP
{ VMN } { LFN }
Figure 1. Architecture of PNEMO
The architecture of PNEMO is shown in Figure 1. In this figure, a VMN
and a nemo composed of a MR and a LFN are attached to a MAG.
Figure 2 shows the signaling flow when a nemo enters a PMIPv6 domain.
When the MR is attached to a PMIPv6 domain, the MAG detects MR's
attachment and acquires MR's identifier. It determines whether the MR
is authorized for the network-based mobility management service.
After the MR is authorized for the network-based mobility service,
the MAG sends the Proxy Binding Update (PBU) message to MR's LMA to
register the current location of the MR.
When the LMA accepts the PBU message, it creates the Binding Cache
Entry for the MR and sets up its endpoint of the bi-directional
tunnel to the MAG. Then the LMA sends the Proxy Binding
Acknowledgement (PBA) message including the HNP and the MNP to the
MAG that the MR attaches to.
When the MAG receives the PBA message, it sets up its endpoint of the
bi-directional tunnel to the LMA and also sets up the forwarding
state for nemo's traffic. To emulate the Home Link of the MR, the MAG
configures certain link local addresses. Then, it sends the Router
Advertisement (RA) message to the MR.
The MR configures its address using the HNP advertised by the MAG and
it advertise the RA message including the MNP to the nemo.
If there is a LFN in the nemo, the LFN configures its address using
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the MNP. The LMA and the MAG have proper routing states for handling
the traffic sent to and from the nemo using the address from its MNP.
+-----+ +----+ +-----+ +-----+
| LFN | | MR | | MAG | | LMA |
+-----+ +----+ +-----+ +-----+
| | | |
| Attached | |
| | | |
| | Detect Attachment event |
| | (Acquire MR-ID/ Profile) |
| |-- Rtr Sol ----->| |
| | |-- PBU ------------>|
| | | Accept PBU
| | | (Allocate HNP/MNP,
| | | Setup BCE/Tunnel)
| | |<------------ PBA --|
| | Accept PBA |
| | (Setup Tunnel and Routing) |
| | | |
| | |== Bi-Dir Tunnel ===|
| |<----- Rtr Adv --| |
| | (HNP,MNP) | |
| IP Address | |
| Configuration | |
| | | |
|<- Rtr Adv --| | |
| (MNP) | | |
IP Address | | |
Configuration | | |
| | | |
Figure 2. Mobile Router Attachment - Signaling Call Flow
Figure 3 shows the signaling flow for nemo's handoff. The MR moves
from the previously attached MAG (p-MAG) to the newly attached MAG
(n-MAG). When the MR changes its point of attachment to the Internet,
the p-MAG can detect MR's detachment from the access link. The p-MAG
sends a De-registration request message to MR's LMA and deletes the
binding and routing state for the MR. On receiving the request
message, the LMA accepts the request and deletes the binding for the
MR if the LMA does not receive the PBU from the n-MAG within the
timeout.
When the MR is attached to the new link, the n-MAG detects MR's
attachment. Then, the n-MAG sends the PBU message to MR's LMA to
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update the binding state. After the signaling procedure, the n-MAG
sends the RA message to advertise the HNP and the MNP to the MR. The
MR does not detect the changes with respect to the layer-3 attachment
of this interface.
On receiving the RA message from the n-MAG, the MR sends the RA
message with the MNP to the nemo. The LFN receives the RA message and
configures its address if it does not have its address.
In Figure 3, the RS message and the RA message are exchanged between
the MR and the n-MAG. Because the MR has already set its address and
the default router, the MR does not need the RA message.
+-----+ +----+ +-----+ +-----+
| LFN | | MR | |p-MAG| | LMA |
+-----+ +----+ +-----+ +-----+
| | |== Bi-Dir Tunnel ===|
| Detached | |
| | Detect Detachment event |
| | | |
| | | |
| | |
| | +-----+ |
| | |n-MAG| |
| | +-----+ |
| Attached | |
| | Detect Attachment event |
| | | |
| |--(Rtr Sol)----->| |
| | |-- PBU ------------>|
| | | |
| | |<------------ PBA --|
| |<-----(Rtr Adv)--| |
|<- Rtr Adv --| (HNP,MNP) |== Bi-Dir Tunnel ===|
| (MNP) | | |
| | | |
Figure 3. Mobile Network Handoff - Signaling Flow
3.2 Nested network
Figure 4 shows an example of a nested nemo. Figure 5 shows the
signaling flow when a nemo is nested. When another MR (MR2) or a VMN
is attached to the MR (MR1) which is connected to the MAG, MR1
detects MR2's or VMN's attachment. Then MR1 sends the Nested Binding
Update (NBU) message including MR2's or VMN's identifier to the MAG.
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After the MAG receives the NBU message, it determines whether MR2 or
the VMN are authorized for the network-based mobility management
service.
+-----+
| LMA |
+-----+
|
//
//
|
+-----+
| MAG |
+-----+
|
+-----+
| MR1 |
+-----+
_______|_______
| |
+-----+ |
| MR2 | {VMN}
+-----+
|
+-----+
| MR3 |
+-----+
Figure 4. the nested Mobile Network of PNEMO
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+-----+ +----+ +-----+ +-----+
| VMN | | MR1| | MAG | | LMA |
+-----+ +----+ +-----+ +-----+
| | |== Bi-Dir Tunnel ===|
Attach Event | | |
| Detect Attach event | |
| | | |
|- Rtr Sol -->| | |
| |-- NBU --------->| |
| | |-- PBU ------------>|
| | | Create BCE
| | |<------------ PBA --|
| |<--------- NBA --| |
|<- Rtr Adv --| | |
| | | |
Figure 5. Nested Network Attachment - Signaling Flow
Then the MAG sends the PBU message to the LMA to update its binding
state. When the LMA receives the PBU message, the LMA registers MR1's
identifier into MR2's or VMN's upper-router field in the BCE and
updates the tunnel identifier field in the BCE. After the LMA sets up
the BCE, the LMA sends the PBA message to the MAG. On receiving the
PBA message, the MAG registers MR'1 identifier as the upper-router
identifier in the Binding Update List Entry (BULE) that the MAG
manages to maintain the binding state of a nemo. After that the MAG
sets up the routing table to the nested nemo. MR1 receives the Nested
Binding Acknowledgement (NBA) message that the MAG sends to MR1 and
updates the NEMO State Table. MR1 has the mobility information of the
mobile nodes attached to MR1 in the NEMO State Table.
When MR3 or a VMN attaches to MR2, a recursive procedure is needed to
update upper router's NEMO State Table, the BULE, and the BCE. MR2
sends the NBU message to its upper router (MR1). MR1 receives the NBU
message and creates the NEMO State Table related to MR3 or the VMN.
Then MR1 sends the Proxy Nested Binding Update (PNBU) message to the
MAG. After the LMA and the MAG finish their process, MR1 receives the
Proxy Nested Binding Acknowledgement (PNBA) message. Then MR1 updates
its NEMO State Table and sets up the routing table. MR1 sends the NBA
message to MR2. MR2 updates its NEMO State Table after receiving the
NBA message.
Figure 6 shows the handoff procedure when a nemo is nested. Even if a
nemo is nested, the handoff procedure is the same as the non-nested
case. The LMA and the MAG also update the entries for the nodes in
the nested nemo. When the LMA and the MAG receive the signaling
message such as the PBU, they check all entries in its binding table.
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If an identifier in the upper router field equals to the Mobile Node
Identifier option in the signaling message, the LMA and the MAG find
that this entry must be updated.
+-----+ +-----+ +-----+ +-----+
| VMN | | MR2 | | MR1 | | MAG |
+-----+ +-----+ +-----+ +-----+
| | | |
Attach Event | | |
| Detect Attach event | |
| | | |
|- Rtr Sol -->| | |
| |-- NBU --------->| |
| | |-- PNBU ----------->|
| | | |- PBU ->
| | | |
| | |<----------- PNBA --|
| |<--------- NBA --| |
|<- Rtr Adv --| | |
| | | |
Figure 6. Nested Mobile Network - Signaling Flow
4. Local Mobility Anchor Operation
In order to manage the binding states of the MR and the VMN, some new
functions MUST be added to the LMA.
The LMA MUST have the function that allocates and manages the MNP. In
order to forward the packets to LFN's address configured using the
MNP, the LMA MUST intercept the packets destined to the MNP.
To update the BCEs for the MR and the VMN in the nested nemo, the
format of the PBU and the PBA messages MUST be extended. The PBU and
the PBA message MUST have the Mobile Network Prefix option. This
option informs the LMA and the MAG of the prefixes that are allocated
to the nemo. The PBU and the PBA messages MUST also have the Upper
Mobile Router option. This option informs the LAM and the MAG of the
identifier of the upper MR to which the VMN and the MR are attached.
The upper MR MUST be the MR that is attached to the MAG directly.
The format of the BCE in the LMA MUST be extended to manage the MNP
and the upper MR's identifier. The BCE has the R flag field in order
to indicate whether or not this BCE is created for a MR or a single
node. For a MR, this flag is set to value 1 and is set to value 0 for
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a single node. The BCE in the LMA also has the Mobile Network Prefix
field to manage the MNP. Besides, the BCE in the LMA has the Upper
Mobile Router field. In the nested nemo scenario, if the LMA receives
the signaling messages such as the PBU including the MR's identifier,
the LMA updates the BCE for MR's identifier and the BCE whose upper
router field equals to the MR's identifier. The LMA can manage the
mobility of the nested nemo.
5. Mobile Access Gateway Operation
In order to manage the binding states of the MR and the VMN, some new
functions MUST be added to the MAG.
The format of the BULE MUST be extended to manage the mobility of the
nemo and the nested nemo. The Mobile Network Prefix field, the Upper
Mobile Router field and the R flag must be added to the BULE in the
MAG. If the R flag in the BULE is set to value 1, the entry is for a
MR. If this R flag in the BULE is set to value 0, the entry is for a
single node. The identifier of the Upper Mobile Router Identifier
option in the signaling message from the MR is stored into the upper
mobile router field.
In order to manage the mobility of the nested nemo, PNEMO defines the
following new signaling messages, the Nested Binding Update (NBU),
the Netsted Binding Acknowledgement (NBA), the Proxy Nested Binding
Update (PNBU) and the Proxy Nested Binding Acknowledgement (PNBA).
Figure 7. shows the formats of the new signaling messages. The NBU
and the NBA have the P flag and some Mobility options. If the P flag
is set to value 1, this signaling message is called the PNBU or the
PNBA. The NBU and the PNBU have the Mobile Node Identifier option,
the Home Network Prefix option, the Mobile Network Prefix option and
the Upper Mobile Router Identifier option as the Mobility Options.
The NBA and the PNBA have the Mobile Node Identifier option, the Home
Network Prefix option, the Mobile Network Prefix option as the
Mobility Options and the P flag.
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Nested Binding Update Massage
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Nested Binding Acknowledgement 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Status |P| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7. A Format of New Signaling Messages
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+-----+
| LMA |
+-----+
|
+-----+
| MAG |
+-----+
|
+-----+
+------| MR1 |--------+
| +-----+ |
| | |
| +-----+ |
| +--| MR2 |----+ |
| | +-----+ | |
| | | | |
| | +-----+ | |
| |+-| MR3 |--+ | |
| || +-----+ | | |
| |+----------+ | |
| +-------------+ |
+---------------------+
Figure 8. An Example of a Nested NEMO
Figure 8 shows an example of a nested nemo. When the MAG receives the
NBU message from MR1 after MR2 is attached to MR1, the MAG creates an
entry for MR2 in the BULE. The MAG registers the identifier of MR2 in
the Mobile Node Identifier option with the Mobile Node Identifier
field in this entry and registers the identifier and the link local
address of MR1 with the Upper Mobile Router field and the Linklocal
Address field in this entry, respectively. After authentication, the
MAG sends the PBU message to its LMA.
If the MR3 is attached to MR2, the MAG receives the PNBU message from
MR1. As the MAG receives the NBU message, it sets up the binding
states. Then the MAG sends the PBU message to its LMA. The LMA sends
the PBA message containing the HNP and the MNP to allocate them to
the nested nemo. After the MAG receives the PBA message, it updates
entries for MR2 and MR3. Then the MAG sends the NBA or the PNBA
message to MR1.
6. Mobile Router Operation
Each MR MUST have the NEMO State Table (NST) to manage the location
of the nested nemo. The NST has the Mobile Node Identifier field, the
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Home Network Prefix field, the Mobile Network Prefix field, the
Mobile Node Linklocal Address field and the Upper Mobile Router
field.
The Mobile Node Identifier field has the identifier of the nested MR
(e.g., MR2) attached to the MR (e.g., MR1). The Home Network Prefix
field and the Mobile Network Prefix field have the prefixes that are
allocated to the nested nemo. The link local address in the Mobile
Node Linklocal Address field is the next hop node's link local
address to the HNP and MNP. MR's identifier in the Upper Mobile
Router field is the next hop node's identifier to the destination.
The signaling flow of the nested nemo is shown below. In Figure 8,
MR1 is connected to the MAG and MR2 is connected to MR1. When MR3 is
attached to MR2, MR3 sends the Router Solicitation (RS) message to
MR2.
MR2 detects MR3's attachment and creates the NST for MR3. MR2 sends
the NBU message whose Mobile Node identifier option is set to the
identifier of MR3 and whose Upper Mobile Router option is set the
identifier of MR2 to MR1.
After MR1 receives the NBU message, MR1 creates an entry for MR3 in
the NST. Its Mobile Node Identifier field is set to the identifier of
MR3 and its Upper Mobile Router field is set to the identifier of
MR2. Then MR1 sends the PNBU message containing MR1's identifier in
its Upper Mobile Router option to the MAG.
After the MAG updates its BULE and the LMA updates its BCE, the MAG
sends the PNBA message to MR1. When MR1 receives the PNBA message, it
sets a lifetime in its NST. Then MR1 sends the NBA message to MR2.
MR2 updates its NST and extracts the HNP and the MNP from the NBA
message. Then the MR2 sends the Router Advertisement (RA) message to
advertise the HNP and the MNP to MR3.
MR3 configures its address using the HNP and sends the RA message
with the MNP to its network.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3775] D. Johnson, "Mobility Support in IPv6", RFC 3775, June
2004.
[RFC3963] V. Devarapalli, "Network Mobility (NEMO) Basic Support
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Protocol", RFC 3963, January 2005.
[RFC5213] S. Gundavelli, Ed. "Proxy Mobile IPv6", RFC 5213, August
2008.
Authors' Addresses
Tetsuya Arita
Graduate School of Science and Technology, KEIO University
3-14-1 Hiyoshi, Kohoku-ku
Yokohama, Kanagawa 223-8522
Japan
Phone: +81-45-566-1425
EMail: cream@tera.ics.keio.ac.jp
URI: http://www.tera.ics.keio.ac.jp/
Fumio Teraoka
Faculty of Science and Technology, KEIO University
3-14-1 Hiyoshi, Kohoku-ku
Yokohama, Kanagawa 223-8522
Japan
Phone: +81-45-566-1425
EMail: tera@ics.keio.ac.jp
URI: http://www.tera.ics.keio.ac.jp/
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