Mobility Extensions for IPv6 (MEXT) J. Kim, S. Koh
Internet Draft Kyungpook National University
Intended status: Informational H. Jung
Expires: September 2012 ETRI
Y. Han
KUT
March 5, 2012
Use of Proxy Mobile IPv6 for Distributed Mobility Management
draft-jikim-dmm-pmip-00.txt
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Abstract
This document discusses how to use the Proxy Mobile IPv6 (PMIP)
protocol for distributed mobility management. Specifically, we
describe the two schemes of distributed mobility management: Signal-
driven PMIP (S-PMIP) and Signal-driven Distributed PMIP (SD-PMIP).
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Table of Contents
1. Introduction ................................................ 3
2. Conventions used in this document ........................... 5
3. Operations .................................................. 5
3.1. Overview ............................................... 5
3.2. Signal-driven PMIP(S-PMIP) ............................. 6
3.2.1. Procedures ........................................ 6
3.2.2. LMA Operations .................................... 7
3.2.3. MAG Operations .................................... 8
3.3. Signal-driven Distributed PMIP(SD-PMIP) ................ 8
3.3.1. Procedures ........................................ 8
3.3.2. MAG Operations .................................... 9
4. New Messages ............................................... 10
4.1. Proxy Binding Query(PBQ) .............................. 11
4.2. Proxy Query ACK(PQA) .................................. 11
5. Security Considerations .................................... 12
6. IANA Considerations ........................................ 12
7. References ................................................. 12
7.1. Normative References .................................. 12
7.2. Informative References ................................ 12
8. Acknowledgments ............................................ 13
1. Introduction
Most of the existing protocols for Internet mobility support are
based on the centralized approach, as shown in the Mobile IPv6 (MIP)
and Proxy Mobile IPv6 (PMIP), in which all control and data traffic
will be processed by a centralized mobility anchor, such as Home
Agent (HA) of MIP or Local Mobility Anchor (LMA) of PMIP. The
centralized mobility anchor allows a mobile host to be reachable,
when it is not connected to its home domain, by ensuring the
forwarding of packets destined to or sent from the mobile device.
However, such a centralized mobility scheme is vulnerable to some
problems. First, the centralized anchor may induce unwanted traffic
into the core network, which tends to give a big burden to mobile
network operators in terms of operational costs. In addition, a
single point of failure of the central anchor may affect overall
data transmission and degradation of performance, which will
increase the cost of network dimensioning and engineering.
To overcome the limitations of centralized mobility management, the
IETF has recently discussed the distributed mobility management. The
distributed mobility management can be classified into the partially
distributed approach, in which only the data plane is distributed,
and the fully distributed approach where both data plane and control
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plane are distributed. In the centralized management, the routing
path through a centralized anchor tends to be longer, which results
in non-optimal routes and performance degradation, whereas the route
optimization will be intrinsically supported in the distributed
management. Moreover, the distributed mobility management can reduce
unnecessary traffics, if the two end hosts communicate directly each
other, not relying on a centralized anchor. This will also be
helpful to reduce the handover delay. Moreover, the centralized
approach is vulnerable to a single point of failure, whereas the
distributed approach will mitigate such problem to a local network.
In the partially distributed approach, the control plane is
separated from the data plane, and only data plane will be
distributed for route optimization. First, a mobile node (MN) is
connected to a mobility agent (MA). Then, the MA binds the location
of MN with the control function. If a correspondent node (CN) sends
a data packet toward MN, the MA will find the location of MN by
contacting with the control function, in which location query and
query acknowledgement messages can be exchanged. Based on the
obtained location information, the MA of CN can deliver the data
packets directly to the MA of MN. Now, the data packet is forwarded
to MN.
In the fully distributed architecture, both control plane and data
plane are distributed and it can be further classified into the
data-driven multicast/broadcast scheme and the peer-to-peer search
scheme. However, the data-driven multicast/broadcast scheme seems to
be not effective, since unnecessary data packets may be excessively
generated in the domain, since the data packets will be delivered by
multicast to all the MAs in the domain. On the other hand, in the
peer-to-peer search scheme, just before transmission of data packets,
a searching process will be activated among MAs in the domain to
find the location of MN. After network attachment, CN transmits a
data packet to its MA. The MA of CN will find the location of MN by
using an appropriate searching mechanism, such as the distributed
hash table (DHT). Then, the MA of MN will respond to the MN of CN.
Now, the MA of CN delivers the data packet to the MA of MN. The data
packet will be forwarded to MN.
In this document, we discuss how to implement the distributed
mobility management in the PMIP-based mobile networks. Based on the
PMIP, we describe the two schemes of distributed mobility management:
Signal-driven PMIP (S-PMIP) and Signal-driven Distributed PMIP (SD-
PMIP). S-PMIP can be regarded as a partially distributed approach,
whereas SD-PMIP corresponds to the fully distributed schemes.
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In this document, we will only focus the distributed mobility
management for 'intra-domain' movement of MN, since there are
various possible scenarios for 'inter-domain' movement.
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 [RFC2119].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
3. Operations
3.1. Overview
Table 1 summarizes the main features of the existing PMIP scheme and
the proposed distributed mobility management schemes, S-PMIP and SD-
PMIP.
Table 1. Comparison of PMIP and Proposed DMM Schemes
+---------+------+--------------+---------+-----------+-----------+
| Scheme |Agents| Mobility | Binding | Data | Binding |
| | | Architecture | Update | Delivery | Query |
+---------+------+--------------+---------+-----------+-----------+
| PMIP | MAG | Centralized | Used | Data | Not Used |
| | LMA | | | driven | |
+---------+------+--------------+---------+-----------+-----------+
| S-PMIP | MAG | Partially | Used | Signal | Used |
| | LMA | Distributed | | driven | (unicast) |
+---------+------+--------------+---------+-----------+-----------+
| SD-PMIP | MAG | Fully | Not Used| Signal | Used |
| | | Distributed | | driven |(multicast)|
+---------+------+--------------+---------+-----------+-----------+
The existing PMIPv6 can be regarded as a centralized architecture,
in which Mobile Access Gateway (MAG) performs the Proxy Binding
Update (PBU) operation with LMA, and the data packets are first
delivered to LMA and then forwarded to MN. Therefore, all control
and data traffics concentrate on the LMA.
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S-PMIPv6 is a partially distributed architecture in which the
control plane is separated from the data plane. The PBU operation
will be performed between MAG and LMA, as done in PMIP. In the
packet delivery operation, however, the MAG of CN first finds the
CoA of MN, just before data delivery, by contacting with LMA. To do
this, the MAG of CN will transmit a newly defined Proxy Binding
Query (PBQ) message to LMA, and the LMA will respond with a newly
defined Proxy Query ACK (PQA) message to the MAG. These newly
defined PBQ and PQA messages will be specified in the next section.
In this sense, this scheme is named 'signal-driven' scheme. After
that, the MAG of CN will deliver the data packet directly to the MAG
of MN, and further to MN.
SD-PMIPv6 is also a fully distributed architecture, which is similar
to the peer-to-peer search scheme. No PBU operation is performed. In
the data packet delivery, on the other hand, MAG of CN will find the
MAG of MN by using sending a PBQ message to all of the MAGs in the
PMIP domain by multicast. The MAG of MN will respond with a PBA
message. After that, the MAG of CN will deliver the data packet
directly to the MAG of MN, further to MN.
3.2. Signal-driven PMIP(S-PMIP)
3.2.1. Procedures
+-----+
2.PBU | | 5.PBQ
+-------------->| LMA |<--------------+
| | | |
| +-----+ |
| | | |
| | | |
+-----+ 3.PBA | | 6.PQA +-----+
| |<------------+ +------------>| |
8.Data | MAG | 7.Data | MAG | 4.Data
++===| |<==============================| |<==++
|| +-----+ +-----+ ||
|| ^ ||
|| | ||
|| | 1. Connection setup ||
\/ | (HoA Acquisition) ||
+----+ | +----+
| MN |---+ | CN |
+----+ +----+
Figure 1. S-PMIP Operations
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Figure 1 shows the operation of S-PMIP. First, MN setups a PMIP
connection with MAG and obtains its HoA (step 1). The MAG sends a
PBU message to LMA to bind HoA and CoA of MN (step 2). On receiving
the PBU request, LMA will create the associated binding cache entry,
and send a PBA message to the MAG (step 3). Now, CN sends a data
packet to MN (step 4). Then, the MAG of CN sends a PBQ message to
LMA to find the CoA (i. e., IP address of MAG) of MN (step 5). On
the reception of PBQ, the LMA responds with a PQA message including
the CoA of MN to MAG of CN, after lookup of its binding cache (step
6). During this process, MAG of CN may buffer the data packets
received from CN to prevent the packet losses. After establish the
tunnel, the MAG of CN sends its buffered data packets first. After
that, the MAG of CN sends the data packet to MAG of MN (step 7).
Finally, the data packet is forwarded to MN (step 8).
3.2.2. LMA Operations
For distributed mobility management of S-PMIP, the LMA must support
the functional capability described in this section.
On receiving a PBQ message from MAG, the LMA must perform the
following operations.
1. Check if the PBQ message contains the Q flag set to 1.
2. Find the CoA of MN by looking up the binding cache of LMA.
3. If the corresponding HoA-CoA entry is found in the binding
cache, LMA will respond to MAG of CN with a PQA message
containing a success indication. Otherwise, if not found, LMA
will respond with the PQA containing a failure indication.
The responding PQA message from LMA to MAG of CN is constructed as
follows.
1. Source address field in the IP header must be set to IP address
of LMA
2. Destination address filed in the IP header must be set to IP
address of the MAG of CN
3. The PBA message MUST include the CoA of MN.
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3.2.3. MAG Operations
For distributed mobility management of S-PMIP, each MAG in the
domain must support the functional capability described in this
section.
When a data packet arrives at CN, the MAG of CN must send a PBQ
message to LMA so as to find the CoA of MN. During this query
process, MAG of CN may buffer the data packets received from CN to
prevent the packet losses. The detailed issue of how to buffer the
data packets from CN is for further study.
The PBQ message from MAG to LMA must be constructed, as specified
below.
1. Source address field in the IP header must contain the IP
address of MAG.
2. Destination address filed in the IP header must contain the IP
address of LMA.
3. The PBQ message must include the HoA of MN.
On receiving a PQA message from LMA, the MAG of CN must perform the
following operations.
1. Check if the PQA message contains the Q flag set to 1.
2. If the PQA message contains any failure, the associated
information may be forwarded to CN, which is for further study.
Otherwise, if it contains a success indication, the MAG of CN
must establish a tunnel with the MAG of MN for data delivery.
Then, the MAG of CN will first forward the data packets
buffered, if any. The subsequent data packets will be delivered
directly from MAG of CN to MAG of MN.
3.3. Signal-driven Distributed PMIP(SD-PMIP)
3.3.1. Procedures
Figure 2 shows the operation of SD-PMIP. The MN setups a PMIP
connection with the MAG (step 1). When CN sends a data packet to MN
(step 2), the MAG of CN sends a PBQ message all the MAGs in the
domain by multicast (step 3). For multicast transmission, it is
assumed that all the MAGs in the domain have already been subscribed
to a specific multicast address in the initialization process. Note
that all the MAGs in the domain are under the control of the same
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network administrator, and that the multicast transmissions will be
allowed only within the local PMIP domain. In the multicast
transmission, the MAG of CN will encapsulate the original data
packet by adding an outer IP header for multicasting, in which the
destination address is set to a multicast address and the source
address is set to IP address of MAG of CN.
+-----+
| | 3.PBQ
+-------------->| MAG |<--------------+
| | | |
| +-----+ |
+-----+ 3.PBQ +-----+
| |<------------------------------| |
6.Data | | 4.PQA | | 2.Data
++===| MAG |------------------------------>| MAG |<==++
|| | | 5.Data | | ||
|| | |<==============================| | ||
|| +-----+ +-----+ +-----+ ||
|| ^ | | 3. PBQ | ||
|| | | MAG |<--------------+ ||
|| | | | ||
|| | +-----+ ||
|| | ||
|| | 1. Connection setup ||
\/ | (HoA Acquisition) ||
+----+ | +----+
| MN |---+ | CN |
+----+ +----+
Figure 2. SD-PMIP Operations
For the PBQ message transmitted by multicast, only the MAG of MN
will respond with a PQA message to MAG of CN (step 4). All the other
MAGs in the domain must ignore and drop the PBQ packet. Note that
the responding PQA message ensures that the further subsequent data
packets of CN can be delivered directly from MAG of CN to MAG of MN
by unicast. Now, the data packet will be delivered to MAG of MN
(step 5), and further to MN (step 6).
3.3.2. MAG Operations
For distributed mobility management of SD-PMIP, each MAG in the PMIP
domain must support the functional capability described in this
section. In this section, we will describe the control operations of
PBQ and PQA. Note that the data delivery operations of SD-PMIP are
the same with those of S-PMIP.
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When a data packet arrives at CN, the MAG of CN must send a PBQ
message to MAG by multicast so as to find the CoA of MN. During this
query process, MAG of CN may buffer the data packets received from
CN to prevent the packet losses. The detailed issue of how to buffer
the data packets from CN is for further study.
The PBQ message from MAG to all the other MAGs must be encapsulated
by IP-in-IP tunneling, with the following outer header.
1. Source address field of outer header must contain the IP
address of MAG.
2. Destination address filed of outer header must contain a pre-
specified multicast address.
3. The PBQ message must include the HoA of MN.
On receiving a PBQ message from MAG of CN, the MAG of MN must
respond with a PQA message, as specified below.
1. Check if the PBQ message contains the Q flag set to 1.
2. Find the CoA of MN by looking up the binding cache of MAG.
3. If the corresponding HoA-CoA entry is found in the binding
cache, the MAG of MN will respond to the MAG of CN with a
success indication. Otherwise, if not found, it may not respond
or may respond with a failure indication.
The responding PQA message of MAG of MN to MAG of CN is constructed
as follows.
1. Source address field in the IP header must be set to the IP
address of MAG of MN.
2. Destination address filed in the IP header must be set to the
IP address of MAG of CN.
4. New Messages
In the S-PMIP and SD-PMIP schemes, the following two messages are
newly defined. The PBQ message is an extension of the PBU message,
whereas the PQA message is an extension of the PBA message.
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4.1. Proxy Binding Query(PBQ)
The PBQ message is made by adding a new flag (Q) to the PBU message
of PMIP. The rest of the PBU message remains unchanged.
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 # |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A|H|L|K|M|R|P|Q| Reserved | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Query Flag (Q)
A new flag (Q) must be set, if the PBU message is used to find
the CoA of MN in S-PMIP and SD-PMIP. In the normal PMIP operation,
the flag must be set to 0.
4.2. Proxy Query ACK(PQA)
The PQA message is made by adding a new flag (Q) to the PBA message
of PMIP. The rest of the PBA message remains unchanged.
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 |K|R|P|Q|Reserve|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence # | Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Mobility Options .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Query Flag (Q)
A new flag (Q) must be set, if the PBA message is used as a
response to the PBQ in S-PMIP and SD-PMIP. In the normal PMIP
operation, the flag must be set to 0.
5. Security Considerations
TBD
6. IANA Considerations
TBD
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.
[2] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2234] Crocker, D. and Overell, P.(Editors), "Augmented BNF for
Syntax Specifications: ABNF", RFC 2234, Internet Mail
Consortium and Demon Internet Ltd., November 1997.
7.2. Informative References
[1] Johnson, D., et al., "Mobility Support in IPv6", RFC 3775,
June 2004.
[2] Gundavelli, S., et al., "Proxy Mobile IPv6", RFC 5213, August
2008.
[3] Chan, H., et al., "Problem Statement for Distributed and
Dynamic Mobility Management", IETF Internet-Draft, draft-chan-
distributed-mobility-ps-02, March 2011.
[4] Yokota, H., et al., "Use case Scenarios for Distributed
Mobility Management", IETF Internet-Draft, draft-yokota-dmm-
scenario-00, October 2010.
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[5] Liu D., et al., "Distributed Deployment of Mobile IPv6", IETF
Internet Draft, draft-liu-mext-distributed-mobile-ip-00, March
2011.
[6] Patil B., et al., "Approaches to Distributed mobility
management using Mobile IPv6 and its extensions", IETF
Internet Draft, draft-patil-mext-dmm-approaches-00, March 2011.
[7] Kuntz R., et al., "A Summary of Distributed Mobility
Management", IETF Internet Draft, draft-kuntz-dmm-summary-00,
May 2011.
[RFC3775] D. Johnson, C. Perkins, and K. Arkko, "Mobility support in
IPv6", RFC 3775, June 2004.
[RFC5213] S. Gundavelli, K. Leung, V. Decarapalli, K. Chowdhury, and
B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
8. Acknowledgments
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Ji In Kim
Kyungpook National University, KOREA
Email: jiin16@gmail.com
Seok Joo Koh
Kyungpook National University, KOREA
Email: sjkoh@knu.ac.kr
Hee Young Jung
Electronics and Telecommunications Research Institute, KOREA
Email: hyjung@etri.re.kr
Youn-Hee Han
Korea University of Technology and Education, KOREA
Email: yhhan@kut.ac.kr
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