PERFORMANCE EVALUATION OF A NEW ROUTE OPTIMIZATION TECHNIQUE FOR MOBILE IP

International Journal of Network Security & Its Applications (IJNSA), Vol.1, No.3, October 2009
PERFORMANCE EVALUATION OF A NEW ROUTE
OPTIMIZATION TECHNIQUE FOR MOBILE IP
Moheb r. Girgis1
, Tarek m. Mahmoud1
,
Youssef s. Takroni1
and hassan s. Hassan1
1
Computer Science Department, Minia University, El- Minia,61519, Egypt.
moheb@mail.minia.edu.eg , Tarek_2ms@yahoo.com , ysaad@mail.minia.edu.eg and hassan@mail.minia.edu.eg
ABSTRACT
Mobile ip (mip) is an internet protocol that allows mobile nodes to have continuous network connectivity
to the internet without changing their ip addresses while moving to other networks. The packets sent from
correspondent node (cn) to a mobile node (mn) go first through the mobile node’s home agent (ha), then
the ha tunnels them to the mn’s foreign network. One of the main problems in the original mip is the
triangle routing problem. Triangle routing problem appears when the indirect path between cn and mn
through the ha is longer than the direct path. This paper proposes a new technique to improve the
performance of the original mip during the handoff. The proposed technique reduces the delay, the
packet loss and the registration time for all the packets transferred between the cn and the mn. In this
technique, tunneling occurs at two levels above the ha in a hierarchical network. To show the
effectiveness of the proposed technique, it is compared with the original mip and another technique for
solving the same problem in which tunneling occurs at one level above the ha. Simulation results
presented in this paper are based on the ns2 mobility software on linux platform. The simulations results
show that our proposed technique achieves better performance than the others, considering the packet
delay, the packet losses during handoffs and the registration time, in different scenarios for the location
of the mn with respect to the ha and fas.
KEYWORDS
Mobile IP; Tunneling, Route Optimization; Triangle Routing; Handoff Delay; Packet Loss;
Registration Time.
1. INTRODUCTION
Today, the number of wireless and mobile devices connected to the Internet is strongly growing.
Wireless links and networks, mobile users and mobility-related services form an increasing part
of the Internet infrastructure. These wireless and mobile parts are normally connected to larger,
wired networks. Mastering the key concepts in mobile, wireless and wired technology areas are
therefore of increasing importance in the society of today. Mobile IP is an Internet protocol,
defined by the Internet Engineering Task Force (IETF) that allows users keep the same IP
address, and stay connected to the Internet while roaming between networks. The key feature of
Mobile IP design is that all required functionalities for processing and managing mobility
information are embedded in well-defined entities, the Home Agent (HA), Foreign Agent (FA),
and Mobile Nodes (MNs) [1, 2]. When a MN moves from its Home Network (HN) to a Foreign
Network (FN), the correct delivery of packets to its current point of attachment depends on the
MN's IP address, which changes at every new point of attachment. Therefore, to ensure packets
delivery to the MN, Mobile IP (MIP) allows the MN to use two IP addresses: The Home
address and Care-of-Address (CoA). The home address is static and assigned to the MN at the
HN; CoA on the other hand is dynamic and represents the current location of the MN [2].
63

Original MIP has many problems such as home agent faults tolerance [14], HA overloading,
and triangle routing problem. Triangle routing problem is considered as one of the main
problems facing the implementation of MIP. When a Corresponding Node (CN) sends traffic to
the MN, the traffic gets first to the HA, which encapsulates this traffic and tunnels it to the FA.
The FA de-tunnels the traffic and delivers it to the MN. The route taken by this traffic is
triangular in nature, and the most extreme case of routing can be observed when the CN and the
MN are in the same subnet [6, 7]. Many protocols have been invented to solve the triangle
routing problem, such as forward tunneling and binding cache [2], bidirectional route
optimization [8], the smooth handoff technique [11], a virtual home agent [12], and a port
address translation based route optimization scheme [9]. Also, Kumar et al. [19] presented a
route optimization technique in which the tunneling is done at one level above the HA in a
hierarchical network instead of tunneling at the HA.
This paper proposes a new technique for solving the triangle routing problem in Mobile IP and
reducing the delay which is not acceptable for real time applications such as Voice over IP
(VoIP). The proposed technique reduces the packet delay, the packet loss and the registration
time for all the packets transferred between the CN and the MN. In this technique, tunneling
occurs at two levels above the HA in a hierarchical network instead of tunneling at the HA. To
evaluate the performance of the proposed technique, a simulation is carried out using NS-2
simulator on Linux platform [16, 17, 18]. In this simulation the proposed technique is compared
with the original MIP and the “one level up” technique proposed by Kumar et al. [19].
The rest of this paper is organized as follows. In section 2, we introduce the original MIP
operations. The proposed technique used to improve the performance of the original MIP is
described in section 3. Performance evaluation and experiments results are presented in section
4, followed by the conclusion in section 5.
2. Original MIP Operations
MIP supports mobility by transparently binding the home address of the MN with its CoA.
Some specialized routers known as mobility agents maintain this mobility binding. Mobility
agents are of two types - home agents and foreign agents. The HA is a designated router in the
home network of the MN, which maintains the mobility binding in a mobility-binding table, as
shown in Table 1. The purpose of this table is to map the mobile node's home address to its CoA
and forward packets accordingly.
Table 1. Mobility-Binding Table
MN's Home Address MN's care-of-Address Lifetime (sec)
193.227.47.250
193.227.47.30
...
128.172.23.78
118.133.22.94
...
90
135
...
Foreign agents are specialized routers on the foreign network where the MN is currently
visiting. The foreign agent maintains a visitor list, which contains information about the mobile
nodes currently visiting that network. Table 2 shows an instance of a visitor list.
Table 2. Visitor list
MN's Home Address
MN's Home Agent
Address
MAC Address
Lifetime
(sec)
193.227.47.250
131.193.17.3
...
193.227.47.100
131.193.17.100
...
00-00-21-00-95-c9
00-40-51-00-33-a9
...
120
160
...
The original MIP involves three operations: Agent discovery, Registration and Tunneling.
64

2.1 Agent Discovery
The MN is responsible for discovering whether the MN is in a home or foreign network. This
process is done by either the Agent Advertisement or Agent Solicitation communication process
[13]. Usually, the FA periodically broadcasts the Internet Router Discovery Protocol (IRDP)
message [13] in its own network to let the visited MN know the FA is here and what services
the FA provides (Agent Advertisement). Thus, the MN knows which network it belongs to. In
case the MN does not receive this message, it can request the service by sending a solicitation
message to inform the FA directly (Agent Solicitation). If there is no answer back during a
limited time, the MN attempts to use the Dynamic Host Configuration Protocol (DHCP) to
acquire a new IP address. [1, 13].
2.2 Mobility Agent with Registration
The purpose of the registration process in MIP is to inform the mobility agent with a mobile
node’s new IP address and update the binding information between home address of the mobile
node and its CoA. This allows TCP connections to be maintained without a disruption and
correspondent nodes to communicate with mobile nodes directly. Once a mobile node has a
CoA, it registers its CoA with its home agent so that the home agent knows where to forward its
packets as shown in Figure 1. Depending on the network configuration, the mobile node could
either register directly or indirectly [1, 2]. The indirect registration steps are as follows:
a) The mobile node sends a Registration Request to the prospective foreign agent to
begin the registration process.
b) The foreign agent processes the Registration Request and then relays it to the home
agent.
c) The home agent sends a Registration Reply to the foreign agent to permit or deny
the request.
d) The foreign agent processes the Registration Reply and sends it to the mobile node.
MN HA
t
FA
RegistrationRequest
RegistrationRequest
Registration
Reply
Registration
Reply
Figure 1. Indirect Registration
2.3 Mobility Agent with Tunneling
In order to deliver packets from the MN to the HA and vice versa, either the FA or the MN has
to do tunneling to avoid the route propagation problem. After the tunnel is established, it is
considered as just only one hop end-to-end from either the FA or the MN to the HA. Basically,
there are three kinds of encapsulation technique. First, a traditional IP-in-IP encapsulation [3]
simply encapsulates the original IP packet within the new IP header. Second, Perkins proposed
the idea of the Minimal Encapsulation, used to avoid the repetition of the IP fields [4]. Third,
The Generic routing encapsulation (GRE) [5] is another tunneling protocol, which supports
various kinds of transport protocols over IP network.
65

3. DESCRIPTION OF THE PROPOSED TECHNIQUE
This section describes our proposed technique to solve the triangle routing problem of MIP to
reduce the handoff delay, packet loss and the registration time. A MN initiates a handoff
whenever it enters into an area of a mobility agent different from its current area. During a
handoff, MN is unreachable and packets may be lost if no buffering scheme is used.
A hierarchical network is considered for the new technique, in which the routers and nodes
are arranged logically in the form of parents and children [15]. The network is divided into
domains clubbed together to form higher level domains and so on till one reaches at the top,
which is known as the root. The hierarchical network helps in organizing and managing the
network. It represents an idealized Internet where optimal paths are used. Our hierarchical
network consists of 4 levels contains the HA, FAs, MN, and standard IPv4 nodes without
mobility support as illustrated in Figure 2. The addressing system used in this network model
consists of 3 levels of hierarchy: domain.cluster.node, according to NS2 simulator. In the
proposed technique as the MN moves away from its HN, it registers a new CoA with the HA.
The HA forwards the new CoA and all information related to the MN to a router that has the
same functionality as a mobile agent and resides two levels above the original HA, which we
refer to as surrogate HA (SHA). The packets destined for MN is tunneled at that router instead
of the HA node, which saves the transmission time. Theses steps can be summarized as follows:
1. Mobility agents (HA and FA) advertise their presence using its agent advertise
messages.
2. The MN receives an agent advertisement message and determines whether it is in the
HN or in a FN
3. When MN detects that it is in a FN, it requests a CoA from this FN.
4. Then MN registers it’s CoA with it’s HA using the registration and replay messages.
5. The HA forwards the MN’s CoA to the SHA
6. When packets are sent to the MN, they are intercepted by the SHA rather than the
original HA, and then the SHA tunnels them to the MN current location.
Figure 2. Traffic data flow path for the original MIP
66

Figure 3. Traffic data flow path for the proposed technique
To illustrate the triangle problem and the proposed technique we consider the following
example. Suppose that the MN will receive traffic from a correspondent node (W0) which is the
root of the hierarchal tree with an address 0.0.0. If the MN (1.2.1) moves from its HA (1.2.0) to
the FA (1.5.0), the original MIP path will be (0.0.0, 1.0.0, 1.1.0, 1.2.0, 1.1.0, 1.0.0, 1.4.0, 1.5.0)
to the MN as illustrated in Figure 2. In the proposed technique, the new current location of the
MN is forwarded to SHA (1.0.0), so the traffic data flow will take the path (0.0.0, 1.0.0, 1.4.0,
1.5.0), as illustrated in Figure 3. This overcomes the triangle routing problem of the original
MIP and enhances the performance by reducing the delay, the packets loss and the registration
time.
4. PERFORMANCE EVALUATION
In this section we present our simulation results of the original MIP, the “one level up”, and the
proposed technique. Simulations are conducted to investigate three critical performance issues,
i.e. packet delay, packet loss during handoffs and registration time. The simulations are run
using the open source NS2 simulator from Lawrence Berkeley National Laboratory (LBNL),
which is widely used in the networking community to study IP networks. In the network model,
it is assumed that all the routers have mobility support and the router one level and two levels
above the home agent can keep the current position of mobile in its routing table. It is also
assumed that the router one level and two levels above the home agent is capable of performing
the encapsulation (IP in IP). The random mobility pattern’s movement scenario for our
simulations were generated using the setdest utility of NS2, with one MN, the grid area, the
maximum speed, traffic type, link delay, transmitter range, bandwidth, packet rate, packet size,
and simulation time as its parameters. The parameters values that have been used for the
mobility simulations are summarized in Table 3.
67

Table 3. Parameters used during Mobility Simulations
Parameter Value
grid area 1000 x 1000 m
maximum speed 75 m/s
traffic type Constant Bit Rate (CBR)
Link delay 20 ms
transmitter range 150 m
bandwidth 2 Mb
packet rate 5 Packet/sec
packet size 200 byte
simulation time 20 s
Five simulation scenarios are considered to evaluate the performance of the considered
techniques. Each scenario is based on the point of attachment and mobility of MN. The handoff
delay, the packet loss and the registration time are calculated in each scenario for each
technique, and the results are presented in the form of graphs and tables. For all simulation
scenarios, the mobile traffic starts from 0.5 sec and the handoff occurs at about 16 sec and
terminates at about 18 sec.
Scenario A: The MN (1.2.1) is connected to FA (1.3.0)
As can be seen in Figure 4, the handoff delay for the proposed technique and the one level up
are about 0.046 sec at simulation time 16 sec, while the handoff delay for the original MIP is
about 0.052 sec at the same simulation time.
The packet loss is given in Figure 5, in which the number of packet losses during the handoff
for the proposed technique is less than the one level up and the original MIP.
Figure 4. Handoff delay Comparisons of Scenario A
68

Figure 5. Packet loss Comparison of Scenario A
Scenario B: The MN (1.2.1) is connected to FA1 (1.5.0)
As illustrated in Figure 6, the handoff delay for the proposed technique, one level up, and the
original MIP are about 0.062 sec, 0.065 sec and 0.070 sec respectively. These values occur at
simulation time 16 sec. As in scenario A, the number of packet losses during the handoff for the
proposed technique is less than the one level up and the original MIP techniques, as shown in
Figure 7.
Figure 6. Handoff delay Comparisons of Scenario B
Figure 7. Packet loss Comparison of Scenario B
69

Scenario C: The MN (1.2.1) is connected to FA2 (0.2.1)
This scenario considers the case of existing the MN in a different domain. As can be seen in
Figure 8, the performance of the proposed technique is better than both the one level up and the
original MIP. The handoff delay for the proposed technique is about 0.061 sec and for the one
level up is about 0.069 sec at simulation time 16 sec, while the handoff delay for the original
MIP is about 0.072 sec at the same simulation time.
for the proposed technique is also less than the one level up and the original MIP.
Figure 8. Handoff delay Comparisons of Scenario C
Figure 9. Packet loss Comparison of Scenario C
Scenario D: The MN (1.2.1) is connected to FA3 (0.1.0)
This scenario illustrates the case of existing the MN in a different cluster in the domain
considered in scenario C. As can be seen in Figure 10, the handoff delay for the proposed
technique is about 0.04 sec and for the one level up is about 0.053 sec at simulation time 16 sec,
while the handoff delay for the original MIP is about 0.060 sec at the same simulation time.
for the proposed technique is also less than the one level up and the original MIP.
70

Figure 10. Handoff delay Comparisons of Scenario D
Figure 11. Packet loss Comparison of Scenario D
Scenario E: The MN (1.2.1) is returned to it’s HA (1.2.0)
In this case, the handoff delay are almost the same for the proposed technique, the one level up
technique, and the original MIP and it is about 0.11 sec at simulation time about 2 sec as
illustrated in Figure 12. The number of packet losses during handoff for the proposed technique
is much lower compared with both the one level up and the original MIP techniques as shown in
Figure 13.
Figure 12. Handoff delay Comparisons of Scenario E
71

Figure 13. Packet loss Comparison of Scenario E
The other parameter considered in the simulation experiments is the registration time.
The registration time is the time the MN takes to register and make conversation with the FA.
Comparisons for registration time for the original MIP, the one level up and the proposed
technique are presented in tables 4 and 5. The first column in tables 4 and 5 contain the address
of FA serves the MN. As can be seen in these tables, it is clear that the registration times for the
proposed technique are generally better than the other two techniques.
Table 4. Registration time values (in sec) for the original MIP and the proposed techniques
Through
FA
Original
MIP
Proposed
Technique
Improvement%
1.5.0 0.808378 0.406199 49.75135395
0.2.1 1.206543 0.803992 33.36399946
0.1.0 0.808922 0.40611 49.79614845
Table 5. Registration time values (in sec) for the one level up and the proposed techniques
Through
FA
One
level up
Proposed
Technique
Improvement%
1.5.0
0.60603
1
0.406199 32.97389077
0.2.1 1.00670 0.803992 20.13612754
0.1.0 0.60673 0.40611 33.06599949
5. CONCLUSION
In this paper, we proposed an efficient approach to deal with triangle routing problem in Mobile
IP. Unlike the conventional MIP, tunneling process of the proposed approach occurs at two
levels above the home agent in a hierarchical network instead of at home agent. Compared with
other proposals, our proposal has primary advantages. The proposed mechanism can reduce
packet delay, packet loss during handoff, and registration time. That is, unlike original MIP, a
mobile node does not send any more registration update message to home agent after obtaining
the new IP address. Instead, the location information for the mobile node is only updated at
Surrogate Home Agent (SHA) (two levels above home agent). The simulation results, which are
based on NS2 simulator, show that the proposed approach has a better performance compared to
both the original MIP and the one level up technique. In future work, more experiments will be
done to study the effect of increasing the levels above the home agent.
72

REFERENCES
1. C. Perkins, “Mobile IP”, IEEE Transactions on Communication, 35(5) (1997), 84-99.
2. C. Perkins, IP Mobility Support for IPv4, 2002, IETF RFC 3344.
3. C.Perkins, IP Encapsulation within IP, 1995, RFC 2003.
4. C.Perkins, Minimal Encapsulation within IP, 1996, RFC 2004.
5. D. Farinacci, T. Li, S. Hanks, D. Meyer, P. Traina, Generic Routing Encapsulation (GRE), 2000,
RFC 2784
6. T. Janevski,.Traffic Analysis and Design of Wireless IP Networks. Artech House Publishers. Boston,
London, 2003.
7. C. Perkins, and D. Johnson, Route Optimization in Mobile IP, Internet Draft, (2000).
8. C. Wu, A. Cheng, S. Lee, J. Ho, and D. Lee, “Bi-directional Route Optimization in Mobile IP Over
Wireless LAN”, Institute of Information Science, Academia Sinica, Taiper, Taiwan, (2), (2002)., 1168-1172.
9. D.Badami. , N. Thanthry, T. Best, R. Bhagavathula, R. Pendse, "Port Address Translation based Route
Optimization For Mobile IP”,. Vehicular Technology Conference, (5) (2004), pp 3110-3114.
10. Hao Chen, Route Optimization on Mobile IP over IPv4, (2002), Final Project,.
11. B.Ayani, , Smooth Handoff in Mobile IP, Master Thesis, University of California in Berkeley 2005.
12. G. Qiang and A. Acampora, “ A Virtual Home Agent based Route Optimization for Mobile IP”, Wireless
Communication and Networking Conference, IEEE, Center for Wireless Communications, California
University, San Diego, La Jolla, Ca, USA, (2) (2000), pp 592-596.
13. Jon Postel, ICMP Router Discovery Messages, (1991) RFC 1256.
14. Y. Huang, and M. Chuang, “Fault tolerance for home agents in mobile IP” Elsevier North-
Holland. (50) (2006), pp 3686 – 3700.
15. E. Pitoura, and I. Fudos, “Efficient hierarchical scheme for locating high mobility users”,
Proceedings of the 6th
conference on information and knowledge management. (1988).
16. K. Daniel Wong, “Smarter route optimization for Mobile IP”. IEEE 16th International
Symposium on Personal, Indoor and Mobile Radio Communications, (2005), pp 1550 – 1554.
17. K. Fall, and K. Varadhan, the NS manual, available at http://www.isi.edu/nsnam/ns/ns-
documantation.html.
18. M. Greis. Tutorial for the UCB/VINT Network Simulator ns, available at
http://www.isi.edu/nsnam/ns/tutorial/index.html
19. C.Kumar, N. Tyagi, and R. Tripathi,. Performance of Mobile IP with New Route Optimization Technique.
IEEE International Conference, Institute of Engineering and Rural Technol, Allahadad, India, (2005), pp
522-526.
73

PERFORMANCE EVALUATION OF A NEW ROUTE OPTIMIZATION TECHNIQUE FOR MOBILE IP

More Related Content

What's hot (17)

Similar to PERFORMANCE EVALUATION OF A NEW ROUTE OPTIMIZATION TECHNIQUE FOR MOBILE IP (20)

Recently uploaded (20)

PERFORMANCE EVALUATION OF A NEW ROUTE OPTIMIZATION TECHNIQUE FOR MOBILE IP