Internet DRAFT - draft-tian-sa-mip
draft-tian-sa-mip
Internet Engineering Task Force J. Tian
Motorola
Internet Draft A.Helal
Document: draft-tian-sa-mip-00.txt University of Florida
Expires: November 1 2006 May 2006
MIP SPEED EXTENSION
<draft-tian-sa-mip-00.txt>
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Copyright (C) The Internet Society (2006).
Abstract
The speed extension to the Mobile Internet Protocol provides a way
for the Foreign Agents and Home Agents to perceive the moving speed
of the Mobile Nodes. With the speed information popularized in the
mobile IP network, the behavior of the Mobile IP implementation with
speed adaptive algorithm implemented will automatically adapt to the
speed of the Mobile Node so that the performance of the Mobile IP
won’t decline dramatically in a rapid moving environment. At the same
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time, the Mobile IP speed adaptive algorithm only requires reasonable
resources that are enough for seamless handoff.
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 [i].
Table of Contents
1. Introduction...................................................2
2. Performance of MIP and the moving speed of MN..................3
2.1 Performance of MIP at different moving speeds..............3
2.2 Relationship between Performance of MIP and moving speeds of
MN.............................................................3
3. Speed adaptive MIP (SA-MIP)....................................4
3.1 Foreign Agent set size.....................................4
3.2 MIP speed extension........................................5
3.3 SA-MIP handoff procedure...................................6
4. Security Considerations........................................6
References........................................................7
Author's Addresses................................................7
Full Copyright Statement..........................................7
Acknowledgments...................................................8
1. Introduction
While TCP/IP successfully overcomes the barriers of time and distance
in a wired network, mobile IP is a promising technology to eliminate
the barrier of location for the increasing wireless internet usage.
Third generation (3G) services combine high speed mobile access with
IP-based services. 3G networks are based on a set of radio technology
standards such as CDMA2000, EDGE and WCDMA. Mobile IP (MIP) can be
used as the common macro mobility management framework to merge all
these technologies and allow mobile users to roam between different
access networks.
Throughout history, the economic wealth of people or a nation has
been closely tied to transportation efficiency. A person can drive a
car on high way at speed of 80miles/h. Some high speed trains such as
France TGV, Japanese bullet, German maglev can travel at speeds of
over 200 miles/h. Could people surf the internet, communicate with
families and enjoy an online movie while traveling at high speeds?
Could the current network infrastructure support rapid mobility?
A review on recent research on MIP shows a great amount of efforts
contributed to reducing MIP handoff latency. [1] proposed two
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mobility protocols, pre- and post-registration, using L2 trigger. In
pre- registration, MN may communicate with both oFA (old Foreign
Agent) and nFA (new Foreign Agent). In post-registration, data are
cached in nFA before the registration is completed. Fast-handover [2]
for Mobile IPv6 network combines the about two methods. But they all
depend on L2 (layer 2). S-MIP[3], uses MN location and movement
patterns to ‘instruct’ the MN when and how handoff should be carried
out. [4] also uses MN’s movement model to predict handoff. But all
these efforts didn’t consider the speed factor of MN, which may cause
problems when the MN moving rapidly.
2.
Performance of MIP and the moving speed of MN
MIPv4[5] is designed independently from all Layer 2 technologies. In
order to evaluate the performance of MIP in rapid moving
environments, without losing generality, 802.11b is used as the Layer
2 technology to evaluate the performance of MIP.
2.1 Performance of MIP at different moving speeds
The experiment results shows that the time-sequence graph and
throughput graph at speed 20m/s and Access Point(AP) distance 1000m
are similar to those graphs at speed 10m/s and AP distance 500m. Also
the time-sequence graph and throughput graph at speed 80m/s and AP
distance 1000m are similar to those graphs at speed 40m/s and AP
distance 500m, as well as those graphs at speed 20m/s and AP distance
250m. If double the moving speed of MN and at the same time double
the AP distance, the average throughput shows no suggestive
difference.
2.2 Relationship between Performance of MIP and moving speeds of MN
The experiment also shows that the handoff overall time doesn’t
change with speed and effective time/total travel time ratio
decreases when the speed increases.
Let Pavg – Average throughput
Pmaxavg – Average throughput without handoff
Ttravel – Total travel time
Teffective – Total effective time for ftp transmission
Thandoff – Total handoff time while traveling
Khandoff – The number of handoffs while traveling
thandoff – Average handoff time among 7 times of handoff
Then, Pavg = (Pmaxavg / Ttravel ) x Teffetive
= Pmaxavg (Ttravel – Thandoff )/ Ttravel
= Pmaxavg (1 – Thandoff / Ttravel)
= Pmaxavg( 1 – Khandoff x thandoff / Ttravle)
= Pmaxavg( 1 – (Khandoff / Ttravle ) x thandoff ))
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Since thandoff doesn’t change, The change of Pavg is caused by
Khandoff/Ttravel ratio.
Define MN handoff rate as rh = v/d, which is the ratio of the MN’s
speed and the cell size(AP distance). It means that how many APs or
FAs the MN hands over in one second. rh is also equal to Khandoff /
Ttravel.
The relationship between the performance of MIP over WLAN and the
moving speed is presented in the following equation:
Pavg = Pmaxavg( 1 – rh x thandoff ) (1)
Where Pavg is the average throughput for the MN; Pmaxavg is the
average throughput without handoff. thandoff is the average handoff
time (in second) for every handoff procedure.
3. Speed adaptive MIP (SA-MIP)
Equation 1 shows that the performance of MIP depends on the MN
handoff rate. rh is also equal to the ratio of Khandoff/Ttravel,
where Khandoff is the number of handoffs occurred during the MN
traveling. Ttravel is MN’s total travel time. To reduce rh without
changing total travel time, the number of handoffs needs to be
reduced. The optimal is Khandoff = 0
3.1 Foreign Agent set size.
Let N be the total FA numbers on the way MN travels. Let’s assume M
is the number of FAs with whom the MN can communicate without L3
handoff delay. The optimal is let M = N. But this costs too many
resources, especially when the number of active MNs is large. It's
hard to know how long the MN will travel at the beginning.
Let M be the size of the FA Set with whom the MN can communicate
without L3 handoff delay. From IP level of view, M is the number of
FAs that MN has registered to and can communicate with at that
moment.
Now the question is:
1. How to decide FA set size M
2. How to guarantee MN can communicate with a FA set almost like to
do with a single FA.
For question 1, equation 6 gives the FA set size.
M = | thandoff x rh | + 1 (2)
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In this equation, thandoff is the handoff time for every handoff
procedure, and rh is the handoff rate. The value of thandoff can be
an experimental measurement result. rh is dynamic.
For question 2, the solution is to let MN pre-register M potential
FAs along the way MN travels, at the same time let IP packets be
multicasted to those M FAs in this FA set. So MN will not experience
any handoff delay from the IP level of view.
In SA-MIP, the set of FAs that MN can talk to without L3 latency is
extended from one point at low moving speed to a line at high moving
speed. The length of the line dynamically changes with the MN handoff
rate. The behavior of SA-MIP will automatically adapt to the handoff
rate of the MN so that the performance of SA-MIP won’t decline
dramatically in a rapid moving environment. At the same time, SA-MIP
only cost reasonable amount of resource that is appropriate for
seamless handoff.
3.2 MIP speed extension
MN’s registration message is extended by speed extension. According
to Mobile IP Vendor/Organization-Specific Extensions[6]. Two
Vendor/Organization Specific Extensions are allowed for MIP, Critical
(CVSE) and Normal (NVSE) Vendor/Organization Specific Extensions. The
basic difference is when the CVSE is encountered but not recognized,
the message containing the extension must be silently discarded,
whereas when a NVSE is encountered but not recognized, the extension
should be ignored, but the rest of the Extensions and message data
must still be processed. the NVSE extension format is use for the
speed extension.
The format of the speed extension is as shown below. It follows
the format of NVSE extension.
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 = 134 | Length | reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor/Org-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Speed-Type | Speed-Value
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Normal Vendor/Organization Specific Extension
Type NVSE-TYPE-NUMBER 134
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Length Length in bytes of this extension, not including the
Type and Length bytes.
Reserved Reserved for future use. To be set to 0.
Vendor/Org-ID
The high-order octet is 0 and the low-order 3 octets are
the SMI Network Management Private Enterprise Code of the
Vendor in network byte order, as defined in the Assigned
Numbers RFC [7]. 5400 may be used here.
Speed-Type Indicates the type of speedExtension. Number 10 indicates
the Speed-Value is an absolute speed value. Number 11
indicates the Speed-Value is value of handoff rate in
FAs/second.
Speed-Value When the Speed-Type is 10, this value is an absolute
speed value in meters/second. When the Speed-Type is 11,
this value is a handoff rate in FAs/second.
3.3 SA-MIP handoff procedure
Whenever the MN needs to handoff to a new FA set, after it gets a new
agent advertisements, it sends a registration request with up-to-date
speed or handoff rate information to the very first FA in a new FA
set. The first FA relays the registration request to upper FA or HA.
Meanwhile, it decapsulates the speed extension, refill the MIP header
and authentication extension and then forward it to other FAs(M-1
FAs) in this FA set. These other FAs relay the registration request
to upper FA or HA as well, just like the request comes from the MN.
When the GFA or HA received these registration requests, it builds up
tunnels downwards to each FA and responses with a registration reply.
When the FA received the registration reply, it builds up tunnel
upwards to the GFA or HA. Whenever the MN setups the Link-layer
contact with the FA, the later forwards the registration reply to the
former. The MN gets the care-of-address from agent advertisement
message or registration reply message, and begins data communication.
At the same time, it sends registration request to the new FA with
up-to-date speed or handoff rate information. This new FA
decapsulates the registration request message and sets up a new FA
set. The new FA refill the MIP header and authentication extension
and then forward it to other FAs in this FA set and repeats the above
process.
4. Security Considerations
This document assumes that the MIP registration messages with speed
extension are authenticated using a method defined by the Mobile IP
protocol. This document does not impose any additional requirements
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on Mobile IP messages from a security point of view. So this is not
expected to be a security issue.
References
[1] K. El Malki et al., “Low latency handoffs in mobile IPv4”,IETF
draft-ietf-monileip-low-latency - handoffs -v4-04.txt, 2002
[2] R. Koodli, "Fast Handovers for Mobile IPv6" IETF draft-ietf-
mobileip-fast-mipv6-08.txt, 2003
[3] R.Hsieh, G.Zhou, and A.Seneviratne, S-MIP: "A Seamless Handoff
Architecture for Mobile IP". Proceedings of INFOCOM, San Francisco,
2003
[4] N.Van den Wijngaert, and C.Blondia, “An Urban Mobility Model
and Predictive Hando ver Scheme for Mobile IP”, Proceedings of
OPNETWORK 2004, Washington D.C., 2004.
[5] C.Perkins,RFC3344,“IP Mobility Support for IPv4”, August 2002.
[6] G. Dommety K. Leung, "Mobile IP Vendor/Organization-Specific
Extensions" RFC 3115, April 2001.
[7] Reynolds, J. and J. Postel, "Assigned Numbers", STD 2, RFC
1700, October 1994
Author's Addresses
Jun Tian
Motorola
600 North U.S. Highway 45, MS:AN2
Libertyville, IL 60048
Phone: 847-877-5809
Email: jacky.tian@motorola.com
Abdelsalam (Sumi) Helal
University of Florida
P.O. Box 116120
Gainesville, Florida 32611-6120
Phone: 352-392-6845
Email: helal@cise.ufl.edu
Full Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
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except as set forth therein, the authors retain all their rights.
"This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE
INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgments
The authors would like to thank Janise McNair, Dapeng Wu, Paul
Fishwick and Markus Schneider for their useful discussions.
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