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Effects of Different Packet Sizes in Mobile IPv6 Real-time

Communication

Bi-Lynn Ong, Suhaidi Hassan

Faculty of Information Technology

Universiti Utara Malaysia

06010 Kedah, Malaysia

{s90387@ss.uum.edu.my|suhaidi@uum.edu.my}

Abstract- This paper describes the performance

of Internet protocol version 6 (IPv6) over the wireless

Internet. The performance of mobile IPv6 is evaluated

using the ns-2 network simulator. The simulation

experiment investigates how different packet sizes affect

the throughput and packet latency. The result of the

experiment shows that as the size of packet increases,

normalized throughput increases and inversely normal-

ized packet latency decreases. From the result of the

experiment, we propose the appropriate packet size in

transmitting real-time application over mobile IPv6

environment.

Keywords: Mobile IPv6, packet size, packet la-

tency

1. Introduction

The Internet protocol (IP) transmits various forms of

packet sizes. The commonly used packet sizes are 512

bytes, 1024 bytes, 1280 bytes and 1500 bytes. Differ-

ent packet sizes can cause variation in packet latency

and throughput. Selecting inappropriate packet sizescan cause higher packet latency and packet loss. Con-

sequently, higher packet latency and packet loss can de-

grade the mobile IPv6 performance.

Having understood the importance of selecting ap-

propriate packet size in sending real-time packet over

IP, we conduct a simulation experiment to investigate

the effiect of different packet sizes on the packet latency

and throughput in mobile IPv6 environment.

The rest of this article is organized as follows. In

Section 2, we present the background and the issues to

be covered in this article. In Section 3, we discuss on

the experimental design and setup. Then, we present

the result of the simulation experiment and discussion

in Section 4. Section 5 concludes this paper.

2. Background and Related Work

The basic mobile IPv6 mobility models are discussed

in details in [3], [4], [5], [8].

Toh et al. [7] examined the impact of varying packetsize, beaconing interval and route hop count on route

discovery time, communication throughput, end-to-end

delay and packet loss. The experiment results reveal

that the packet size affects the performance of the end-

to-end ad hoc IPv4 networks, whereas the beaconing

interval has little impact on throughput, end-to-end de-

lay and route discovery time. Since the different packet

sizes affect the end-to end ad hoc IPv4 networks, we

believe that different packet sizes also affect the perfor-

mance of wireless 802.11b LAN in mobile IPv6 envi-

ronment. Hence, we proposea simulation experiment to

examine how different packet sizes affect the through-

put and the packet latency in 802.11b mobile IPv6 en-

vironment. The simulation experiment shows that the

result agrees with the authors.

ElGebaly [2] studied multimedia performance over

the Internet. The author investigated how packet length,

inter-arrival time, jitter, overhead and burstiness af-

fect the multimedia performance. The experiment con-

ducted by the author in the wired IPv4 network using

H.323 protocol. Since packet length and inter-arrival

time affect the performance of wired IPv4 network, we

believe that packet sizes can affect the performance of

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real-time applications in IPv6 network. In [2], trace

files are obtained from the real H.323 IPv4 network.In our simulation experiment, trace files are collected

from simulation experiment because conducting exper-

iments in the real networks may disrupt the operational

network. After we collect the trace files from the sim-

ulation experiment, we further analyze the trace files to

investigate how the packet sizes affect the performance

over the IPv6 wireless Internet.

Elaarag [1] conducted a survey study on Transmis-

sion Control Protocol (TCP) performance over mobile

IPv4 networks. The simulation experiment results show

that TCP is not suitable for mobile hosts and their

wireless links in sending real-time application. Hence,

in our simulation experiment, we evaluate the perfor-

mance of constant bit rate (CBR) over mobile networks.

CBR that runs over User Datagram Protocol (UDP) is

suitable to carry real-time packet.

Our motivation in conducting a simulation exper-

iment is to investigate the performance of mobile

IPv6 when correspondent node (CN) sends different

packet sizes. The objective of the simulation experi-

ment is to examine how different packet sizes affect

the throughput and packet latency. The evaluation

provides information to the researchers in selecting

the appropriate packet size in mobile IPv6 environment.

3. Experiment Design and Setup

Figure 1 shows the network topology used in the sim-

ulation experiment. This topology reflects the setup of

an open space wireless local area network (LAN) envi-

ronment. In wireless LAN, the base station (BS) com-

municates in the length of not more than 30m in diame-

ter. In this simulation experiment, the wireless network

technology is IEEE 802.11b with the bandwidth of 2

Mbps. The network topology is designed in IPv6 envi-

ronment.

CN

0.0.0

HA

1.1.0

N1

1.0.0MN

1.1.0

N2

1.2.0

AR2

1.3.0

AR1

1.4.0

100Mbps, 2ms

100Mbps, 2ms

1.5Mbps, 2ms

2Mbps, 2ms

2Mbps, 2ms

Figure 1: Topology

The topology is divided into 2 domains, first domain

with 1 cluster and second domain with 4 clusters. Eachcluster has 1 node except the third cluster and fifth clus-

ter, which have 2 nodes. The third cluster consists of

the home agent (HA) node and the mobile node (MN)

that are attached to the same hierarchical cluster. The

fifth cluster consists of access router 1 (AR1) and ac-

cess router 2 (AR2) that are attached to the same hierar-

chical cluster. Thus in this simulation experiment setup,

it has a total of 7 nodes with the other 3 nodes attached

to the different hierarchical cluster.

CN is the node that wishes to communication with

MN. In the experimental setup, CN is in the hierarchi-

cal cluster 0.0.0. MN is in the hierarchical cluster 1.1.1

(home cluster). The HA of the MN is in the hierarchi-cal cluster 1.1.0. MN carries the same hierarchical ad-

dress of the HA wherever it moves. N1 and N2 are the

routers with different hierarchical addresses 1.0.0 and

1.2.0. CN and HA connect to N1. N1 is connected to

N2, where AR1 and AR2 are connected to N2. AR1

and AR2 are the BSs. AR1 and AR2 used the same

hierarchical address 1.3.0 and 1.3.1 respectively.

The network model is simulated using ns-2. The ns-

2 version used for this simulation is ns-2.1b6. ns-2.1b6

is deployed with Mobiwan extension and NOAH agent

[6].

The BS signal strength has to be overlapped witheach other. If the radiation of the signal strength is not

overlapped, then the communication between CN and

MN is disconnected in the middle of the communica-

tion when MN moves to the area without radiation sig-

nal. Thus, ns-2.1b6 is deployed with the NOAH agent,

which ensures that the radiation of the signal strength is

overlapping.

Duplex link is the link that enables packet to flow in

both directions from sender to receiver and receiver to

sender. In this network topology, the MN sends binding

update (BU) back to the HA and CN when MN per-

forms handover. MN also updates its location with HA

by sending BU from time to time to the home network.

Thus, the link is set to full duplex link.

CN and HA are connected to node N1 using wired

full duplex link with 100 Mbps. This represents high

speed Ethernet LAN. The link delay in the full duplex

link is set to 2 ms. CN carries CBR traffic. This exper-

imental setup represents networks that carry real-time

application. Queue management is set to droptail since

CN and MN are transmitting real-time applications.

N1 and N2 connect with full duplex link with 1.5

Mbps that represents multi-Megabit T1 service. Queue

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management is also set to droptail because it is trans-

mitting real-time packet. The link delay is set to 2 ms.Both N1 and N2 are set to null agents that send CBR

packet. The connection between N1 and N2 is in wide

area network (WAN).

AR1 and AR2 are connected to N2. It is connected

using full duplex link with 2Mbps with 2ms that repre-

sents the bandwidth and delay of 802.11b technology.

The MN first attaches to AR1, then MN moves with

random motion. AR1 and AR2 are set to null agents

that send CBR packet.

MN is set as a null agent receiving CBR traffic in the

simulation experiment. MN is set to random motion so

that MN freely moves to represent the real situation of

the communication between CN and MN.This simulation experiment uses CBR as the source

traffic. CBR encoding means that the rate at which

the codec output data is constant. It is an application

layer component that generates constant traffic during

the simulation. CBR is useful for real-time audio and

video content on limited capacity channels since it is the

maximum bit rate that matters, not the average. Thus,

CBR is used to take the advantage of all of the capacity.

Our experiment investigates how different CBR

packets affect the packet latency and throughput of the

mobile IPv6 802.11b wireless LAN. In our simula-

tion experiment, the different packet sizes used are 512bytes, 1024 bytes, 1280 bytes and 1500 bytes. Since

1500 bytes is the maximum transfer unit (MTU) of Eth-

ernet LAN, we vary the packet size within 512 bytes to

1500 bytes.

The simulation model is suggested to run on the real-

time audio and video over IP traffic. Thus the transport

layer packets are set as UDP because most of the real-

time packets are running on UDP. TCP congestion con-

trol may cause packets to queue at the router and may

cause delay to the packets. This causes distortion to the

real-time data.

In the simulation experiment, CN sends the CBR traf-

fic. The packets are transmitted through the networks

until the packets reach MN.

The simulation is executed long enough until it

reaches the steady state. Different packet sizes with the

same amount of data are sent in the simulation exper-

iment. The trace files from the simulation experiment

are collected and analyzed.

In the next section, we present the result of the

simulation experiment and the discussion of the results

obtained from the simulation experiment.

4. Results and Discussions

Table 1 presents the result of the simulation experi-

ment. From Table 1, we observe that as the packet size

increases, the throughput increases. The reason is that

sending the same amount of data with smaller packet

size, more packet overheads are sent over the IP. Ta-

ble 1 also shows that as the packet size increases, the

packet latency also increases. The reason is because as

the packet size increases, the networks need more time

to send the packet over the IP.

Packet Size,

(bytes)

Throughput, (%)

Average Packet

Latency (s)512 92.60 0.160

1024 96.08 0.300

1280 96.81 0.369

1500 97.22 0.429

Table 1: Throughput and packet latency for different

packet sizes

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

500 600 700 800 900 1000 1100 1200 1300 1400 1500

Normalizedvalue

Packet size (byte)

Packet Size versus Normalized Throughput and Inversely Normalized Packet Latency

Normalized ThroughputInversely Normalized Packet Latency

Figure 2: Graph on simulation result

The IP performance is proportional to the through-

put and inversely proportional to the packet latency.

Figure 2 presents a plot of packet size versus normal-

ized throughput and inversely normalized packet la-

tency. The plot shows that as the packet size increases,

the normalized throughput increases and the inversely

normalized packet latency decreases. The curves from

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Figure 2 suggest that packet size 512 bytes is the suit-

able packet size to send the CBR packet over the mo-bile IPv6 environment. This is because the normalized

throughput and inversely normalized packet latency in-

tercept at point 512 bytes.

Our result shows that packet size 512 bytes can

improve the performance of mobile IPv6. Therefore,

we propose that real-time packets are packetized into

512 bytes.

5. Conclusion

In this paper, we present the result of simulation ex-

periment on mobile IPv6 in sending real-time appli-

cation. In the simulation experiment, different packet

sizes are sent over the mobile IPv6 environment. The

simulation result shows that among the different packet

sizes, packet size 512 bytes is the most suitable size

to send the CBR packets that carry the real-time audio

and video packets. Thus, we propose that for mobile

IPv6 environment that carries real-time audio and video

packets, the packet size is packetized into 512 bytes

when it is sent to the wireless IPv6 network.

References

[1] H. Elaarag. Improving TCP Performance over

Mobile Network. ACM Computing Surveys,

34(3):357374, 2002.

[2] H. ElGabaly. Characterization of Multimedia

Streams of an H.323 Terminal. Intel Technology

Journal, 2nd Quarter 1998.

[3] Z. G. Kan, J. Ma, J. Luo, and J. P. Hu. Mobile IPv6

and Some Issues for QoS. Internet Society, 2001.

[4] J. F. Kurose and K. W. Ross. Computer Network-

ing A Top-Down Approach Featuring the Internet.

Addison Wesley, 2nd edition, 2002.

[5] B. L. Ong and S. Hassan. Mobile IPv6 Architec-

tures and the QoS Issue on Handover Delay. Na-

tional Seminar 2002, Universiti Teknologi Mara,

November 2003.

[6] B. L. Ong and S. Hassan. Mobile IPv6 Simulation

Using ns-2. NS-2 Workshop, UPM, Malaysia, 2004.

[7] C. K. Toh, M. Delvar, and D. Allen. Evaluating

Communication Performance of an Ad Hoc Wire-

less Network. IEEE Transactions on Wireless Com-

munications, 1(3):402414, 2002.

[8] S. Zeadally and D. Mavatoor. Mobile IPv6 Sup-

port for Highly Mobile Hosts. Proceedings of the

IASTED International Conference, pages 144150,

September 2003.