Reasearch Paper

Evaluation and comparison of TCP and UDP over

Wired-cum-Wireless LAN'Abdul Razaque Rind, 2Khurram Shahzad, 3M.Abdul Qadir

'r786ania2000(yahoo.com, [email protected], 3aqadir(jinnah.edu.pk"2'3Center for Distributed and Semantic Computing (CDSC)Mohammad Ali Jinnah University, Islamabad, Pakistan

Abstract - The great deployment of IEEE 802.11 wirelessnetworks has spawned momentous challenges for future datacommunication. Consumers often criticize the connectivity andperformance related issues. Many of the routing protocols aresuggested for wireless LAN. Prominent steps for selection ofrouting protocols according to the nature of networkenvironment produce better performance. We use DSDV routingprotocols to evaluate the performance of TCP &UDP over wiredcum wireless LAN. We use Network Simulator-2 with differentparameters, generating different speeds of mobile nodes anddifferent link capacity (bandwidth) with same packet size in everyscenario. We compare TCP and UDP in terms of throughput,good put and other significant parameters to justify theirperformance in particular circumstances.

Keywords: TCP, UDP, Throughput, Good put, wired-cum-wireless LAN

1. Introduction

Wireless LAN has great impact on global communicationdue to faster, low cast and interoperability. The future oftechnology has boosted the trends of people towards thisdeployment. Wireless LAN is mostly used in airports, hotelsand coffee shops for better and low cast services. Theperformance of TCP and UDP in wired-cum-wirelessenvironment is different. TCP is mostly designed for wiredenvironment because network nodes have reliable access toinfrastructure network. TCP is not specially designed formobile nodes because network connectivity to the Internetthrough wireless may be unpredictable. Two approachesrequire for enhancing the user experience of TCP applicationsfor mobile environment. First approach is to improve theexisting protocols in order to reduce high error bit rate andhand off time. Second approach is to invoke existing TCPmechanism as a catalyst through any method without anymodification [1].

The performance of TCP is greatly degraded due to high biterror rate found in the wireless network. Making TCPefficient, various approaches have been introduced but itdoesn't achieve any targeted goals in WLAN [1]. The slowstart and congestion avoidance methods have been used toensure appropriate transmission rate. We can use UDP toobtain better performance and protection for real timetransmission Voice over IP and Video Conference. Voice overIP services can be provided on wireless LANs where MVN areequipped with IEEE 802.11 network interfaces, which send IPpackets through access points to the internet [2].

Wired Network has better performance than wirelessNetwork in terms of throughput. The most of the traffics oninternet pertains to the transfer of the jobs including down

loading of audio, video, web pages, file transfer etc can alsobe coordinated by TCP.UDP is faster than TCP because of less overhead of header;

TCP has retransmission and acknowledgement, which makes itslower. Due to increasing demand of bandwidth for real timemultimedia applications supported by new routing andswitching technologies, QoS provision is possible now [22].Different variants of UDP are being introduced by NetworkResearchers but TCP is still dominant in Internet, the factorwhich discourages the performance of TCP, is window basedcongestion control mechanism. Every body is fully aware thatthe performance of TCP is affected in wireless environmentbecause it improperly stops packet loss due to congestion [24].Performance of UDP and TCP is decreased due to multi-hop802.1 1 environments with radio intervention. [24].

Performance of UDP is degraded due to many factors, forinstance Overhead, SNR, Network and host hardware,implementation of network protocols and device drivers [14,15] while performance of TCP is affected due to many factorsinclude congestion window, recovery mechanism, packet size,and timeout values of TCP as well as the acknowledgements,back off mechanism of IEEE 802.11 MAC retransmission andretry limit [16].

Layer-2 hand off time affects the performance of mobilenodes. It is basic reason of packet loss in performancedegrading, especially in case of reliable end-to-endcommunication [3]. There are several affecting factors forthroughput ofWLAN including number of users, interference,micro cell range, and multi path propagation, hardware andstandards support. Latency and bottlenecks are two majorfactors that affect the performance of wireless network whilein the case of wired network, as latency and bottle necks willalso affect the wireless portion [8, 11]. The remainder of thispaper is organized as follows. Section-Il describes the relatedwork, Section-III describes used routing protocol, Section-IVdescribes Simulation Method, Section-V describes SimulationAnalysis of TCP and UDP, Section -VI gives over view ofperformance result, and Section-VII gives the Discussion,finally Section-VIII Summarize our conclusions and futurework.

2. Related work

Xuanming Dong [12] presents new performance model thatmay be accurate in predicting the TCP throughput overRayleigh Fadding channels and use model that captures themain aspect of TCP congestion and flow control. Paper alsopresents UDP performance on several popular high-speedpacket wireless networks due to effects of Doppler spread and

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delay spread.Xavier P 'erez-Costa [16] discuss the wireless adoption layer

which can be implemented for enhancing the genericperformance and produces forward error control mechanismwith enhancement module and considers it important tool forobtaining better performance of TCP and UDP over theessentially untrustworthy wireless channels.M. Bottigliengo at al [17] give proposal and compared the

effectiveness of his task with IEEE 802.1 lb standard, andproved through simulation under TCP and UDP trafficscenario [17].Zhenghua Fu at al [20] analyzed the performance of UDP

over IP-based wired and wireless networks through NS-2.They presented throughput, packet drop and utilizedbandwidth. They also analyzed the degraded performance ofUDP on wired network as compared to wireless network.

Andrea De Vendictis at al [10] gives an analysis of IEEE802. 11 WLAN test bed analysis of TCP/IP traffic and majorproperties of TCP/IP traffic in IEEE 802.11-infrastructurewireless LAN including UDP and TCP traffic performance.Main focus of paper is mostly on TCP characteristics.

Andrea De Vandicts at al [23] gives an analysis of TCP andUDP in wireless LAN 802.1 lb test bed with respect to flowfairness by using single access point and increasing the mobilestations.

Charles R. Simpson at al [18] presents the empirical modelof end user network in which introduce two traffic models asfirst model for specific TCP or UDP port and second modelfor all TCP and UDP traffic ports for end users.

Y. Yi at al [19] describes the relation of TCP and link layerof static ad-hoc network. TCP packet losses occur withoutmobility and performance of TCP is sub-optimal. Our work ismoderately different from other previous work due to differentused parameters and basis of evaluation, analysis andcomparison criteria while such work was not produced prior,using NS2 Simulator.We justify the performance of TCP and UDP on basis of

different aspects. Our work validate to this theoretical idea thatwith increase of MN, the performance of TCP and UDPdecrease.

3. Routing Protocols

We have used the proactive Destination-Sequence DistanceVector (DSDV), as on demand protocols ADV and AODVcannot be used to establish the routes in wireless portion (Ad-hoc) of the network. ADV has no clear route mechanismbecause it is distance vector protocol that avoids long routingroutes and using sequence numbers. DSDV meets thecomplete demand of wired-cumwireless LAN network [11].We have used TCP with FTP and UDP with CBR applicationsas transport protocols.

4. Simulation Method

We used Network Simultor-2. The network we simulatedconsists of different scenarios, which contain differentnumber of nodes randomly placed on 1000m* 1000mtopological grid. The position of Home Agent (HA) is 300,250 and Foreign Agent (FA) is 800, 250 in grid, simulation

time is 80 seconds. We utilize mobility pattern that is basedon random waypoint model. The speed of nodes is uniformlydistributed between 5m/s to 40m/s. We used different linkcapacity include 256Kb, 1Mb, 2Mb, 5Mb and 11Mb. Everylink capacity for both TCP and UDP is used for variousmobile nodes speeds, in order to determine which one isbetter in particular case.We simulate the steady state conditions of network with

various background traffics. UDP packet size is fixed 1000bytes with CBR Traffic as compared to TCP with same packetsize with FTP Traffic. In each simulation scenario, we evaluatethrough put and good put.

Through put is computed as amount of data delivered byTCP and UDP divided by 80 sec.. Good put is the ratio ofTCPand UDP packets successfully delivered and compared withthe total number of the packets transmitted.

5. Simulation Analysis ofTCP and UDPThe test environment consists of wired-cum-wireless

topology having number of variables to accommodate the testcases. Fig.1 shows the wired cum wireless which highlightsthe fixed nodes and inter connecting lines shows the positionsof Home agent and Foreign agent with movements of mobilenodes. Simulation is started at 0.5 sec. We generated differentscenarios with FTP and CBR traffics for TCP and UDPrespectively. During the simulation, each mobile node movesbetween foreign agent and home agent. Here we analyze twoscenarios with different aspects such as different mobile nodes,varying link capacity and speed.

Scenario # 1 indicates the throughput of TCP and UDP withone and thirteen mobile nodes with one foreign agent, onehome agent and one corresponding node.

Scenario # 2 indicates the good put of TCP and UDP withone and thirteen mobile nodes with one foreign agent, onehome gent and one corresponding node

If we increase the mobile nodes that the throughput may bedegraded in the TCP case while for the case of UDPthroughput increase. In addition during different scenariosgood put ofTCP cannot be affected much more but in the caseofUDP good put decrease.

6. Performance Result

We analyze performance of UDP and TCP according tofollowing scenarios.

A. Scenario #1 (Throughput)We use FTP for TCP and CBR for UDP traffic. One

corresponding node communicates with one mobile node.During the communication, mobile node moves from HomeAgent (HA) to Foreign Agent (FA). During the allotted 80second time of simulation, we evaluated the scenarios on thebasis of link capacity such as 256Kb, 1Mb, 2Mb, 5Mb and11Mb. Mobile node's speed is set from ranging 5m/sec,1Om/sec, 20m/sec, 30m/sec and 40m/sec. The size of TCP andUDP packets remains same in all of the scenarios. Thefollowing graphs give analytical comparison of TCP and UDPin detail. Through put can be found by the following formula:

Through put = Packet (size) x delivered packet / Time (sec)

338


95

90

n090 101 02 03 04

-~ 85-

UDP80 (m/s0L- 75-

70

nq10 15 20 25 30 35 40 45

UDTP Speed (mis)

Fig 1: Simulation layout scenario for 13 A

82 -

80 -

-78-76 -

0..m 74 -

= 72 -0 70 -

8680 5 10 15 20 25 30

T TCP Speed (misec)UDP

Fig 2: Comparison ofTCP, UDP w.r.t Link capacity 256having 1 Mobile node (with different spe

I..,

0.-

QF-

90

85

80

75

70

650 5UTCP

--1- UDP

10 15 20 25 30 3

Speed (mis)

Fig 5: Comparison ofTCP, UDP w.r.t Link capacity 11Mb & Throughput,having 1 Mobile node (with different speed)

In this scenario, there are thirteen mobile nodes that movefrom their Home Agent (HA) to Foreign Agent (FA) andcommunicating with one correspondence node (CN), beforeand after the handoff. We use the same link capacity, samepacket size and speed of mobile nodes as same as in previousscenario.With help of scenario # 2 we calculated the throughput of

all ofMN by fixing link capacity to 5Mb where the speed ofmobile nodes to be set to 30m/s.

35 40 45 We evaluate throughput w.r.t mobile nodes, using TCP andUDP. We analyze that by increasing number of mobile nodes,throughput of every mobile node vary from other increasing

iKb & Throughput, number of mobile nodes for both TCP and UDP. The graphsed) for the throughput are given below.

220

170 -

o.120 -

2 70

20 7

5 40 45 n g 10 15 20 25 30 35 40 455 0TCP

UDP Speed (m/s)


U)

0.

n

0

I-

90

85

80

75

70

650 5 10 15 20 25 30 35 40 45TCP Speed (m/s)UDP


Fig 6: Comparison ofTCP, UDP w.r.t Link capacity 256Kb & Throughput,having 13 mobile nodes (with different speed)

200.0

-0

I 150

XL100

= 50

_i_ OX _

+TC 0 20 3.TCP 10 peed (m?s)UDP

40 50

Fig 7: Comparison ofTCP, UDP w.r.t Link capacity 1Mb & Throughput,having 13 mobile nodes (with different speed)

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100

90

80-

70-

60n 10

-4-TCPUDP

20 30 40 50Speed (m/s)

Fig 8: Comparison ofTCP, UDP w.r.t Link capacity 5Mb & Throughput,having 13 mobile nodes (with different speeds)

0

-* TCP

UDP

by the following formula:Good put Delivered packets x 100 Transmitted packets

105 -

-0 95 -

m 85 -

75 -

655-00> 55

450 1 2 3 4 5 6 7 8 9 10 11 12 13 14TCPUDP # of Mobile Nodes

Fig I 1: Good put ofTCP, UDP with 13 MN, speed 30m/s andLinkCapacity256Kb

110

m0

0

10 20 30 40 50 0 70-

Speed (m/s) 60 |n 1 3 4 5 6 7 8 9 10 11 12 13 14

Fig 9: Comparison ofTCP, UDP w.r.t Link capacity I IlMb & Throughput,having 13 mobile nodes (with different speed)

In this scenario, we fix link capacity to 5Mb where thespeed of mobile nodes to be set to 30m/s. We evaluatethroughput w.r.t mobile nodes, using TCP and UDP. Weanalyze that by increasing number of mobile nodes thatthroughput of every mobile node vary from other nodes forboth TCP and UDP. The graphs for the throughput are givenbelow.

100 _

90

80

~70

60

50n 1 2 3 4 5 6 7 8 9 10 11 12 13 14

-+TCPUDP # of Mobile Nodes

Fig 10: Throughput of TCP, UDP with 13 MN, speed 30m/s, Link capacity5Mb

B. Scenario # 2 (Good Put)We evaluate and analyze the good put of all mobile nodes to

use different link capacity. We find that different packet lossoccurs in UDP case especially when we use link capacity256Kb while in case of 5Mb and I Mb packet losses for UDPdecreases. In case of TCP packet loss with different linkcapacity is minimum as compared to UDP (dropped packets tobe retransmitted). We set speed of all mobile nodes to 30m/swith different link capacity such as 256Kb, 1Mb, 2Mb, 5Mband 1Mb for both TCP and UDP. Good put can be calculated

UDPTCP-W-UDP # of Mobile Nodes

Fig 12: Good put ofTCP, UDP with 13 Mobile nodes, speed 30m/s, Linkcapacity 1Mb

105

a)m 91-1

850.o 750

65

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14-4-TCP # of Mobile Nodes_ UDP

Fig 13: Good put ofTCP, UDP with 13 Mobile nodes, speed 30m/s, Linkcapacity 5Mb

Cu

0.1-1

0.0

0

Q

1051009590

85

80

750 1 2 3 4 5 6 7 8 9 10 11 12 13 14TOP # of Mobile Nodes

UDP

Fig 14: Good put ofTCP, UDP with 13 Mobile nodes,Speed 30m/s, Link capacity 11 Mb

340

0.110)0

I-s0

oes_

110I-,enm1 00

900

80

2 70sf-erNbu


In addition with scenario # 2, we calculof all mobile nodes with respect to link cafig show the throughput performance of evlink capacity.

-* MNMN6MN11

MN2-MN7MN12

MN3MN8MN13

80

70

e- 60

0. 50cm

2 40

30

200 1 2 3 4 5 6 7 4

Link Capacity (Mb/<

Fig 15: Comparison of all mobile nodes w.r.t Link Cwith TCP

lated the throughput registration for communication. Thus layer-2, layer-3 andipacity. The fig. and acknowledgement messages affect the performance of TCPery node on varying [2,4,6]. Another performance affecting factor is only one

corresponding node, communicating with many nodes in ourscenario. TCP has capability of retransmission; lost packets are

MN4 MN5 retransmitted because of this, good put for TCP is encouragingMN9 MN10 even number of MNs increase and link capacity change. In

case of UDP, having no signaling message and lesser payloadbut main factor of degrading the performance of good put is noretransmission of lost packets. Communication ofcorresponding node with single mobile, produce encouragingthroughput and good put in form ofTCP with FTP application.The performance of UDP with CBR traffic in case ofsingle mobile node is little bit lesser than TCP but increasingthe number of mobile nodes, can be cause of increasing thethroughput but decreasing good put (packet loss).

Our goal is to obtain additional data for utilizing theservices of UDP and TCP in particular cases in wired cumwireless channel. Our results for both TCP and UDP casesproduce substantial contribution. Losses are caused due to

3 9 10 11 12 many implementations including mobile nodes, using low linkcapacity; Network boundary and speed of mobile nodes are

Tapacity & Throughput having the major factors to degrade the performance of TCPand UDP over wired cum wireless LAN.

8. Conclusion and Future Work4MN1

MN6MN11

MN2MN7MN12

MN3- MN8MN13

MN4MN9

MN5MN10

105

.0

0.

m

0

vF-

95

85

75

65

55

450 1 2 3 4 5 6 7 8 9 10 11 12

Link Capacity (MbIs)

Fig 16: Comparison of all mobile nodes w.r.t Link Capacity & Throughputwith UDP

7. Discussion of Test Results

Our measurements discovered various comparisons of TCP& UDP performance over wired cum wireless LAN due todifferent parameters used in evaluation. Different scenarios areexplained and simulated by NS-2, using various numbers ofmobile nodes. Single node linked with wired area iscommunicating with different mobile nodes, using the UDP &TCP with its applications including CBR and FTPrespectively, playing a role for receiving and transmitting thepackets.Due to the increasing the mobile nodes, the performance is

degraded for both UDP and TCP because in case of TCP,every MN has number of signaling message to complete the

We concluded that TCP is giving better performance (goodput) in case of minimum number of mobile nodes. TCP alsoproduce encouraging results in case of data includes filetransfer, loading of audio, video, web pages etc on internet butIt does not give encouraging performance voice over IP, whilein case of UDP, It is found better in VOIP and even increasingof mobile nodes produce better throughput while maximumpacket losses occur, in consequence the good put to be greatlyaffected If we can bear loss of little data in terms of filetransfer that UDP can also be best choice for fast delivery ofdata. Link capacity and speed of MNs affect the performanceof TCP and UDP. In future we focus on different comparisonof TCP variants and introduce the hierarchical concept inwired-cum-wireless LAN by using NS-2. We also want tointroduce smart cache on access points to reduce latency andsaving packet losses during hand off process.

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