Internet DRAFT - draft-jiang-dmm-ps
draft-jiang-dmm-ps
INTERNET-DRAFT H. Jiang
Intended Status: Proposed Standard Huawei Technologies
Expires: December 31, 2012 June 29, 2012
Problem statement for distributed mobility management
draft-jiang-dmm-ps-00
Abstract
Due to the limitation of sub-optimal routing, reliability and
scalability problems in the centralized mobility management approach,
distributed mobility management approaches are developed to resolve
those problems. However, the proposed distributed mobility management
approaches also bring some new problems. This document mainly
introduces two kinds of approaches classified by the control plane
management mode and proposes the new problems should be resolved in
the future.
Status of this Memo
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Copyright and License Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements and Terminology . . . . . . . . . . . . . . . . . 3
2.1 Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
3. DMM overview . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1 F-DMM solution . . . . . . . . . . . . . . . . . . . . . . . 4
3.2 P-DMM solution . . . . . . . . . . . . . . . . . . . . . . . 4
4 Problem statement . . . . . . . . . . . . . . . . . . . . . . . 5
4.1 Signaling costs . . . . . . . . . . . . . . . . . . . . . . 5
4.2 Resource utilization . . . . . . . . . . . . . . . . . . . . 5
4.3 Deployment problem . . . . . . . . . . . . . . . . . . . . . 6
4.4 Multihoming support . . . . . . . . . . . . . . . . . . . . 6
5 Security Considerations . . . . . . . . . . . . . . . . . . . . 6
5 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1 Normative References . . . . . . . . . . . . . . . . . . . 6
6.2 Informative References . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
With the development of the mobile communication technologies, the
number of mobile subscribers is growing year by year with the result
that the amount of data traffic generated by them is experiencing a
huge growth, and the future traffic amount is unpredictable. More and
more users prefer to user mobile phones and tablet to obtain data
information through wireless technologies. In the meanwhile more and
more mobile Internet applications designed for handheld mobile
terminals have already attracted the attention of most mobile users.
In order to supply the perfect user experiences for those mobile
subscribers to increase the acceptance, the mobile operators SHOULD
adopt the suitable protocols or architecture to management those huge
number of mobile terminals. Thus IETF have proposed some standards to
deal with the mobility management problems for mobile nodes. Typical
protocols include Mobile IPv6 (MIPv6) and Proxy Mobile IPv6 (PMIPv6).
These protocols generally utilize the mobility anchor to handle the
management operations. Thus the key point for those approaches is
based on the centralized theory. However, the centralized approach
has several drawbacks such as sub-optimal routing, scalability
problem, reliability problem and so on.
For overcoming the drawbacks of the centralized mobility management
approaches, the new approach SHOULD be distributed and never utilizes
a central management point to deliver the control and data packets.
Thus the IETF researchers begin to discuss the requirements and
propose the solutions. Then the proposed solutions can be divided
into two kinds: fully distributed and partially distributed. The main
difference is whether the control plane is distributed or
centralized.
However, as other already deployed mobility management protocols,
whether the fully distributed mobility management protocols or the
partially distributed mobility management protocols are not perfect
and with some limitations had to be considered and resolved. So this
document analyzes the model of distributed mobility management and
proposes some problems in the deployment situation.
2. Requirements and Terminology
2.1 Requirements
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].
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2.2 Terminology
In addition to the terminology defined in [RFC5213], the following
terminology is also used:
DMM: Distributed Mobility Management
F-DMM: Fully Distributed Mobility Management
P-DMM: Partially Distributed Mobility Management
NME: Network Management Entity is an access router and allocates the
prefix for MN which attaching to it. It can be used to exchange
messages for MN to complete the mobility management.
CCE: Central Control Entity is a central control unit used to manage
the location and other information for MN in P-DMM.
3. DMM overview
As mentioned above, Distributed Mobility Management (DMM) can be
divided as follows:
3.1 F-DMM solution
In F-DMM solution, Network Management Entity (NME) which achieves the
mobility management is an access router with the function of anchor.
It takes the role of LMA and MAG as in PMIPv6. So when MN attaches
the NME1, NME1 advertises the prefix for MN to configure the IP
address. When MN moves to attach NEM2, NEM2 will advertise the new
prefix to MN and sends a PBU message to NME1. After receiving the
reply PBA message, NME1 will create a tunnel with NME2. So the
traffic transmitted by NME1 will be forwarded to NME2 so as to reach
MN. And so on, the tunnels will be created with the MN's moving
situation.
3.2 P-DMM solution
In P-DMM solution, the Central Control Entity (CCE) is used to
execute the control signaling interaction and manage the statement of
the MN. CCE achieves the control functions as LMA in PMIPv6. When MN
connects to NME1, NME1 advertises the prefix for MN to configure the
IP address. NME1 sends a PBU message to CCE. Then CCE replies a PBA
message to confirm the new registration. When MN moves to NME2, it
gets a new prefix. NME2 sends a PBU to CCE for registration. By
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searching the BCE table, CCE gets former location information of MN
and sends PBU messages to those NMEs. After receiving PBU message,
NME1 will send a PBA message to CCE to confirm and another PBA to
NME2. Then the tunnel will be created between NME1 and NME2. So the
traffic transmitted by NME1 will be forwarded to NME2 so as to reach
MN. And so on, the tunnels will be created with the MN's moving
situation.
4 Problem statement
Although DMM approaches solve some problems caused by centralized
mobility management approaches, it also brings some new challenges
which SHOULD be resolved for the real large scale business
deployment.
4.1 Signaling costs
Signaling cost is measurement criteria to evaluate the mobility
management approach. In F-DMM solution, because the control plane is
also distributed, the way NME to verify if the attachment of MN is
fresh is to send PBU messages to other NMEs. Apparently, in a large
scale network with lots of NMEs, it will cost too much signaling to
get this information. Otherwise, the new solution SHOULD be proposed
to alleviate the signaling cost. In P-DMM solution, When NME sends a
PBU message to CCE after a MN attachment, CCE will sends PBA messages
to all NMEs in the local area to obtain the PBA reply. This cost is
very large if the network domain is large and with many NEMs. For
example, if the MN is moving in a city to get service, then the PBA
messages costs are expensive.
4.2 Resource utilization
In both of two DMM approaches, how to manage the network resource is
also important. Each time when MN attaches to a new NME, it will
create a new tunnel between the new NME and previous NME after the
registration. So when MN keeps on moving in the large network area
and frequently attaching to different NME, then there are many
tunnels between those NEMs. The problem is that most of those tunnels
will be idle after the moving, so it is unnecessary to keep the
mobility session for those cases. Moreover, the number of NMEs
involves the mobility session will increase and become very large. So
Removing some NMEs which MAY not be used such as having long distance
with the latest location of MN.
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4.3 Deployment problem
Whether F-DMM or P-DMM, how to deploy the network architecture is a
head-scratching puzzlement. For F-DMM, the deployment of NMEs depends
on the network area that MN locating. For P-DMM, the location of CCE
is also troublesome. Moreover, CCE also will cause the single point
failure problem. So it only can be used in small area or localized
moving cases. In large area network, mobile operators SLOULD deploy
many CCEs to keep synchronization so as to manage the mobility of MN
conveniently and save the long distance network cost.
4.4 Multihoming support
Up to now, the proposed DMM solutions in IETF have not talking about
the multihoming support for MN. All solutions are just assuming that
MN connects to the network by one interface. So when MN moving, the
mobility handover and session maintaining is very clearly and easy to
achieve. However, in multihoming scenario, how to keep the mobility
session well when one interface of MN moving while other interfaces
remain unchanged is also unclear.
5 Security Considerations
None
5 IANA Considerations
None
6 References
6.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
6.2 Informative References
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC5213, August 2008.
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC6275, July 2011.
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[I-D.yokota-dmm-scenario] Yokota, H., Seite, P., Demaria, E., and Z.
Cao, "Use case scenarios for Distributed Mobility
Management",draft-yokota-dmm-scenario-00 (expired),
October 2010.
[Paper-Distributed.Centralized.Mobility] Fabio, G., Antonio, O.,
Carlos J. Bernardos and Rui, Costa. ,"A Network-based
Localized Mobility Solution for Distributed Mobility
Management", Proceedings of International Workshop on
Mobility Management for Flat Networks (MMFN 2011).
Authors' Addresses
Haisheng Jiang
Huawei Building, No.156 Beiqing Rd.
Z-park ,Shi-Chuang-Ke-Ji-Shi-Fan-Yuan,Hai-Dian District,
Beijing 100095 P.R. China
EMail: haisheng.jiang@huawei.com
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