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Terminal Mobility Support Protocol
IEEE Transaction on mobile computing Vol. 8, No.6, June 2009
Teck Meng Lim, Chai Kiat Yeo, Francis Bu Sung Lee, and Quang Vinh Le
(CS6204)
Advanced topics in mobile computing
NOV.10.2009
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Table of Contents
 MOTIVATIN OF Terminal Mobility Support Protocol (TMSP)
 BACKGROUND OF TMSP (BRIEF MOBILE IP)
 TMSP FEATURES
 COST COMPARISON WITH MOBILE IP, SIP-OVER-MIPV6
 PERFORMANCE ANALYSIS
 CONCLUSION
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Terminal Mobility Support Protocol
(TMSP)




TMSP is a mobility method that resolves IP mobility for
the mobile node(MN) like 802.11 or 802.16.
TMSP uses an innovative IP-to-IP address mapping method
to provide IP address transparency for applications.
TMSP locate a single user using SIP Uniform Resource
Identifier(URI)
TMSP is much more efficient than Mobile IP in terms of the
number of hops as well as overhead.
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Motivation

TMSP is proposed to overcome the drawbacks of Mobile
IP like Triangular routing, packet, redirecting, increased in
IP header size, and the need for new infrastructure
support.

Unlike MIPv4, TMSP uses an IP-to-IP address mapping
method instead of Permanent IP (Home Address) to
acquired current IP (Care-of-Address)binding in Mobile IP.

Unlike MIPv6, TMSP ensures transparency in IP address
with providing Uniform Resource Indicator(URI)-to-IP
address mapping to locate a user and module installed
on MN and CN.
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Background of Mobile IP
1.[1-2]A CN ‘s packets are routed
to a MN via the HA of MN [HA
intercepts these packets]
2.[3] HA makes a tunnel
[encapsulates the original packets
inside a new IP packet] and
forward the packets.
3.[4] After taking off the outer
header, FA forwards the packets
directly to the MN.
Source of the figure : NCC 2009, January 16-18, IIT Guwahati
4.[5-7] The MN sends packets
back to the CN.
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Background of Mobile IP
 Packets are routed via triangular shape
(Triangular routing)
 Required dedicated infrastructure
like a Home Agent(HA)
 Packets can not be sent to directly from a CN to MN
(redirecting)
 In a tunnel from HA to FA or MN, the packet is
encapsulated in a new outer header
(doubles IP packet size from encapsulation)
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Background (Mobile IP)
 In enhanced Mobile IPv6, most of drawbacks such as
triangular routing and packet redirecting can be
removed by the route optimization mode.
So, Packets from CN can be routed directly to the
Care-of-Address of MN and vice versa.
 Examples of Route optimization in MIPv6
Next slide
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Background
(The route optimization in MIPv6)
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Background of Mobile IPv4, IPv6
IP-in-IP tunnel
 The IP-in-IP encapsulation in
tunneling increases the packet
sizes.
This leads to inefficiency for a
small IP packet like a voice
packet.
Added outer header while
a packet is passing through
a tunnel from HA to FA
Source of the figure : http://www.cse.wustl.edu/~jain/cse574-06/ftp/mobile_ip.pdf
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Background (IPSec on IP Mobility)
 IPSec protocol adds security to IP by enabling the sending and
receiving of cryptographically protected packets [Packet level
security]
 A security association(SA) between CN and MN requires
following entities in the Header: Authentication Header[AH],
Encapsulated Security Payload Extension[ESP], and Security
Parameter Index[SPI].
 The SA is only valid at the time of negotiation between CN
and MN using the three entities.
 Once MN enters another network and changes its IP address,
the SA will be invalid.
It means a new Internet Key Exchange(IKE) negotiation that
gives rise to computation overhead and latency must be
performed.
TMSP has a solution that avoids IKE re10
running
Six major features of TMSP
 Does not assign a permanent IP address to each MN
 Uses a single IP address at any time for each network
interface
 Does not introduce new network servers or
infrastructure support to enable IP mobility
 Does not need IP packets redirection
 Does not incur extra IP header extension
 Allows IPSec without rerunning Internet Key Exchange
(IKE)
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Entities of TMSP
5.CN’s/MN’s SIP
Redirection Server (SIP-RS)
2.UserAgent (UA)
1.1
M
Table
1.2
U
Table
1.3
S
Table
Header Restore Module
3.(HRM)
Address mapping Module
4.(AMM)
Correspondent Node
Or Mobile Node
1. Keeps states for each data connection in MN and
its CN
(three linked state-tables)
1.1. Mapping Table (M-table)
- Network ports, SRC IP, DEST IP
1.2. URI table (U-table) - information for CN
- URI and Care-of-Address
1.3. SID table (S-table)
- a mapping between each network port and a
SID
for each network port at MN
2. User agent (UA)
- Application that initiates requests or returns a
response on behalf of the user
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Entities of TMSP
3. IP-to-IP Address Mapping Module (AMM) –
intercepts outgoing and incoming IP and IPSec packets
at the network layer to perform an IP-to-IP address mapping
function
4. IP Header Restoring Module (HRM)
– restores IP address in the IP header of an IPSec packet to
the IP addresses used at the instant
when the connection was first established
5. SIP-Redirection server
– provides a URI to Care-of-Address resolution of each client
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Bootstrapping
 Mobility for an MN begins when its UA completes a SIP registration procedure
with MN’s SIP redirect server, specified in the server part of the SIP URI as
provided by the user.
 MN and CN use SIP register message to register themselves with their
respective SIP-RS.
 It is important to highlight that CN and MN do not need to be registered with
the same SIP redirect server.
A SIP URI is an email-like address that contains two parts: user and
server parts, separated by an “@,” e.g., “user@server” The user part
contains the user name to identify the user and the server part contains the
IP address or domain name of the SIP server.
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Connection establishment
1. A CN sends a SIP invite request
to MN’s the SIP-RS by using
MN’s Care-of-Address.
2. The SIP-RS replies with a SIP
moved temporarily (Msg. No
302) message containing the
Care-of-Address of MN.
3. The CN sends ACK to the SIP-RS
4. By using MN’s new Care-ofAddress, the CN sends a new
invite message to the MN
directly.
5. The MN replies to CN with a OK
message.
6. The CN sends ACK to MN.
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Connection establishment
Kernel
space
Kernel
space
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Connection establishment
Functions called in TMSP entities
 GETHOSTBYNAME (): is called to map SIP URI to the Care-ofAddress
 ‘connect (): usual data connection
 ‘kernel-space-connect ():is called to establish connection with MN.
 ‘accept (): data connection packet is captured
 TMSP-connect-hook (): incorporating function which generates a
unique SID for data connection if IPSec is the requested protocol
and to call its UA to perform
 TMSP-accept (): After accept function for TCP, it registers the
network port number used for the connection and update
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General IP packets’ Pathway
Assume that
1. The CN has acquired a new Care-of-Address, C, from Access point M when this packet
is generated, while the MN has acquired a new Care-of-Address, D, from Access point
N.
2. Both the MN and CN have also informed each other about their new Care-of-Address
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using a SIP invite request procedure
IPSec packets’ Pathway
IPSec module encrypts the packet
as a payload and encapsulate it
with an IPSec header
Application do not need to be
aware of the Care-of-Address
changes on the MN
IP Address transparency
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IPSec packets’ Pathway
 The HRM will replace the source IP address in the IP packets’ header with
RSA(Original IP) IP Header used to generate security checks for IPSec.
Without this IP header restoration, the IP Packet will fail the IPSec
module’s security check.
 This method allows IPSec module to use the share key established at the
instant when the connection is established.
 The AMM replaces2 the destination IP address of the IP or IPSec packet by
the Care-of-Address of the MN based on its entry in the M-Table
 Finally, for IPSec packet, it pastes the MN’s SID into the reserved bits of
the AH
 This packet is then directly routed to the MN. At the network layer of MN,
the AMM replaces the source and destination IP Addresses of the IP or
IPSec packet by the DSA and RSA respectively
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Update procedure
• After MN enters a foreign network, the SIP-Redirection
Server(RS) and CN update the MN’s new Care-of address
 MN uses the SIP registration procedure to inform the change of location to
its SIP-RS.
 MN re-invites its CN using the SIP invite request message to report the
newly acquired Care-of-Address.
 Upon receiving this re-invitation from MN, CN will update the MN’s Careof-Address in its U-Table.
 The MN’s Care-of-Address is used by the AMM to deliver packets to the
current IP address of MN.
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Performance Comparison
Terminology
 When an MN moves, a series of message exchanges begin to keep
the MN’s movement up to date.
 C movement : the total number of hops that messages traversed as
MN moves in a new network
(Cost for a new movement connection establishment with a new
Agent)
 C maintain : the total number of hops that messages traversed to
maintain existing sessions between CNs and MN
(Cost of maintaining the seamless connection as MN moves)
 C tx : counts the number of hops that a message needs to traverse
from CN to MN (Cost as CN sends a message to MN)

TMSP versus MIPv6 basic(=MIPv4) versus application-layer protocol using SIP-MIPv6
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Comparison in terms of Signaling cost,
Transmission cost
Signaling Cost can be broken into Movement cost and Session maintenance cost
 C signaling = C movement + C maintain
 Each cost can be estimated by DA-B which
means the number of hops from A to B
 C protocoltx= Transmission Cost of each protocol
 For simplicity of comparison, we assume that the
DHCP server is one hop away from MN and there
are five hops between two network entities.
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Signaling cost(Movement cost) of
TMSP, MIPv6(basic),and SIP-MIP v6
 When MN moves into a foreign network, it acquires a new IP
address via DHCP.
 In TMSP, it starts a registration procedure using a message pair
(Register and Okay messages) with its SIP-RS.
 While in MIPv6, it starts a binding update procedure using a
message pair (binding update and acknowledgment messages)
with its HA.
In SIP-MIPv6, it triggers both the registration and the binding
update procedures.
http://en.wikipedia.org/wiki/Dynamic_Host_Configuration_Protocol
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Signaling cost(Maintain cost) of
TMSP, MIPv6(basic),and SIP-MIP v6
 When MN moves into a new foreign network, it informs its CNs of its
new Care-of-Address to continue existing sessions.
 In TMSP and SIP-MIPv6, MN informs its CNs using the SIP invite request
messages that consist of a message pair (SIP invite request and okay
messages).
 In MIPv6, MN does not inform its CNs of its new IP address. Thus, it does
not incur any signaling cost.
Eta = the number of CN
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Transmission cost of
TMSP, MIP v6(basic),and SIP-MIP v6
 When TMSP is used, a message transmitted from CN to MN follows the conventional IP
routing for both TCP and UDP packets.
 When MIPv6 is used, a message transmitted from CN to MN is first sent to the MN’s HA
where the message is tunneled to MN. Likewise, a message from MN to CN is reverse
tunneled back to the MN’s HA before it is sent to the CN.
 When SIP-MIPv6 is used, the message route path is
similar to TMSP for UDP packet and is similar to MIPv6 for TCP packet.
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Data Transmission Gain
The hop count is measured from the point a packet is sent from MN to CN
after MN has moved into a new foreign network.
It includes the cost of one movement cost function
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Average Signaling cost
By using C movement and C
maintain, a *Handover cost can
be derived
Where alpha is the possibility
of active handover and 1alpha is idle handover
probability.
* The cost of a handover refers to the duration from
the point a host enters a new network until it has
successfully attained a new IP address
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Data Traffic overhead
The CBR source generates a total of T = R * (8L) * t bits for a duration of ts, where R is
the rate (in packets per second) of the traffic source and L is the size of an IP packet.
For MIPv6, the amount of traffic generated onto the network from CN to MN is given by
where LIP-in-IP is the size of the outer IP header used to encapsulate the packet,
HMIPv6CN-HA is the number of hops from CN to the MN’s HA, and HMIPv6HA-MN is the
number of hops between MN and its HA.
For TMSP, the amount of traffic generated onto the network from CN to MN is given by
where HTMSP is the number of hops between CN to MN.
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The result of traffic overhead
This figure shows the gain in terms of traffic generated when TMSP is used over MIP V6
The X-axis indicates the difference in hops between the triangular route and the direct
Route CN-MN
Gain = TMIPv6 – TTMSP / TMIPV6 For example, if Gain = 0.6, then TTMSP = 0.4 * TMIPV6
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The result of traffic overhead
This figure shows the gain of using TMSP when the number of hops for the direct
Route is fixed at 10, 15, 20, and 25 and the number of the triangular route is fixed at
30 But distributed in proportion
(HMIPv6 CN-HA / HMIPv6HA-MN)
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Effect of TMSP on the throughput of Wireless Lan
 Experiments are run to compare the saturation throughput of an MN using an IEEE
802.11g WLAN interface. MN floods the air channel using a CBR traffic of 30 Mbps.
 The reported throughputs are approximately equal regardless of whether TMSP is
installed on MN. Thus, this shows that TMSP does not affect the achievable throughput
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of the WLAN in this scenario.
Performance of the IP-to-IP
Address mapping
 The additional delay of 0.56 micro seconds (12%) introduced by TMSP is therefore negligible as it
is much smaller than the transmission delay of the minimum frame size of Ethernet. Thus, TMSP will
not affect the transmission rate of a host.
The transmission delay for the minimum frame size (64 bytes) of Ethernet on a 100-Mbps LAN is
approximately 5.12 micro seconds and that for the minimum frame size (512 bytes) of gigabit
Ethernet on a 1-Gbps LAN is approximately 4.10 micro seconds.
Compared to the transmission delay of both, 0.56 microseconds
of delay is reasonable
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Applicability of TMSP
 TMSP provides a perfect solution for seamless communications
 TMSP works for point to point communication software such as
VoIP and Video conferencing
 TMSP does not affect the legacy applications running on a nonTMSP-enabled server
 One biggest limitation of TMSP is that when MN and CN move
and change their IP address at the same time, the IP addresses of
both are not updated correctly
 Due to the reuse of IP addresses, there exists very slight
possibility of IP address mapping confusion for connectionless
service hosted by UDP server (many clients & single port receive)
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Conclusion
 TMSP enables IP mobility for MNs. It creates an association of IP
addresses and port numbers for a connection in MN and its CNs
and uses this association to hide the changes in IP address when
MN moves from one network to another.
 Owing to the manipulation of IP addresses in the IP header of each
packet, TMSP ensures that packets are sent directly between CN
and MN without packet redirection.
 TMSP taps on the pervasiveness of SIP server as an IP directory
service and uses SIP as a signaling mechanism to maintain location
information.
 Each MN is identified by a SIP URI. Thus, TMSP does not require
permanent IP address for each MN, does not require new network
infrastructure support, and does not enforce packet redirecting
during routing.
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Appendix-Mobile IP terminology
Terms
Meaning
Mobility Agent(MA)
Home Agent or Foreign Agent
Home Agent(HA)
A router on a mobile node’s home network. It delivers packets
through a tunnel to a mobile node. It also maintains mapping
between the mobile nodes home address and its care-of address.
Foreign Agent(FA)
A router on a mobile modes visited network. It works as the
default router of the mobile node.
Mobile Node(MN)
A host or router that changes its point of attachment. It keeps its
home IP address regardless of the change of location.
Correspondent
Node(CN)
Either a fixed or mobile host which is communicating with the MN
Care-of Address
(COA)
(usually referred to as CoA) is a temporary IP address for a mobile
device. This allows a home agent to forward messages to the mobile
device.
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Appendix-Mobile IP terminology
Terms
Meaning
COLOCATED COA
(CCOA)
IP Address which belongs to the address in the FA network or DHCP
server which the MN obtains in a registration process (Packets are detunneled at the MN). The FA acts as the default router.
Gratuitous ARP
Sent by the HA to update Address Resolution Protocol (ARP)
tables for all connected hosts
Mobility Binding
Mapping of the HA and the COA
Tunnel
Virtual private channel with an encapsulated packet
http://en.wikipedia.org/wiki/IP_tunnel
Security Parameters
Index(SPI)
Identifies the Security Association (SA) for data-grams between
two nodes. SPI selects the authentication algorithm and secret
either shared key or public key to compute an authenticator.
Foreign agent-based
COA(FCOA)
IP Address of the FA (Packets are de-tunneled at the FA and the FA
sends them to the MN by Layer 2 address)
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Question
Thanks
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