14
Cost and Ef ciency Analysis of NEMO Protocol Entities Md. Shohrab Hossain, Mohammed Atiquzzaman School of Computer Science, University of Oklahoma, Norman, OK 73019, USA Email: [email protected], [email protected] William D. Ivancic NASA Glenn Research Center, Cleveland, OH 44135, USA Email: [email protected] Abstract—To support IP-mobility of networks in motion, IETF proposed Network Mobility (NEMO) protocol that uses various signaling messages to ensure connectivity of the mobile nodes with the Internet and to maintain security of ongoing sessions by protecting the binding updates. As the next-generation wireless and mobile network is supposed to be a unified network based on all-IP technology, compounded by the fact that the number of mobile nodes requiring mobility support has increased signifi- cantly, the cost analysis of mobility protocols and the underlying mobility management entities have become essential to avoid their performance degradation. However, there has been no compre- hensive cost analysis of NEMO protocol entities that considers all possible costs. In this paper, we have developed analytical models to estimate total costs of key mobility management entities of NEMO. We have defined a metric to compute the efficiency of mobility protocol as well as the mobility entities to find out the percentage of resources used for data (payload) delivery. We have presented numerical results to demonstrate the impact of network size, mobility rate, traffic rate and data volume on the total costs and the efficiency of the NEMO protocol and its key entities. Our results show that a significant amount of resources (bandwidth, processing power, transmission power) are required by the mobility entities for transmission, processing of various signaling messages, as well as searching location database. Our cost analysis will thus help network engineers in estimating actual resource requirements for the key entities of the network in future design while analyzing the data transmission efficiencies of these entities. Index Terms—NEMO, mathematical modeling, cost analysis, mobility management entities, mobility protocol. I. I NTRODUCTION To ensure continuous Internet connectivity of networks in motion, IETF proposed NEtwork MObility Basic Support Protocol (NEMO BSP) [1] which is an extension of IETF host- mobility protocol, Mobile IPv6 [2]. NEMO BSP requires dif- ferent mobility agents to exchange various signaling messages to maintain continuous connectivity and security of ongoing sessions between mobile nodes and Internet nodes. In a mobile computing environment, a number of network parameters (such as, network size, mobility rate, trafc rate, data volume) inuence the cost arising from mobility proto- cols. The total cost includes cost related to query messages, updating Home Agents about the change of location of the mobile entity, sending updates to hosts with ongoing commu- nication, and processing and lookup costs by various mobility agents. As the next-generation wireless/mobile network will be a unied network based on all-IP technology, and the number of mobile nodes requiring mobility support has increased signicantly, the cost analysis of mobility protocols as well as the underlying mobility management entities (e.g., home agents, mobile router, etc.) have become essential to avoid performance degradation of the mobility protocol. There have been earlier attempts for signaling cost anal- ysis ( [3]– [10]) of host-mobility protocols, such as, Mobile IPv6 [2], Hierarchical Mobile IPv6 (HMIPv6) [11]. However, these cost analysis are not adequate for NEMO protocols since NEMO has more parameters and cost components and different types of nodes in the mobile network unlike host- mobility protocols. There have been a few works [12]– [14] on the cost analysis of NEMO protocols. However, these cost analysis ignored major cost components relating to mobility management, e.g., cost related to securing location updates, query messages by CN, obtaining IP address by MH, refreshing binding updates, costs of registration messages, etc. Hence, those analysis are incomplete. Moreover, the entity-wise evaluation of costs has not been performed to obtain the load on various mobility entities of the network required for the operation of NEMO protocol. Such analysis is very essential as resource limitations exist for all network entities and this entity-wise evaluation can aid in estimating actual resource requirement of these entities. The main differences of this work are that we have consid- ered all possible costs required for mobility management and have computed total costs of various mobility management entities of NEMO. We have also dened a metric to compute the data transmission efciency of NEMO protocol as well as its key entities. The authors are not aware of any such work. The objective of this work is to analyze the total cost (including data delivery cost) and data transmission efciency of various mobility entities of NEMO and gure out how those costs are affected by various network parameters, such as network size, mobility rate, trafc rate, and data volume. The contributions of this work are: (i) developing math- ematical models to estimate total costs of various mobility management entities of NEMO: home agent for mobile router, home agent for mobile host, mobile router, correspondent JOURNAL OF NETWORKS, VOL. 7, NO. 3, MARCH 2012 427 © 2012 ACADEMY PUBLISHER doi:10.4304/jnw.7.3.427-440

Cost and Efficiency Analysis of NEMO Protocol Entities · Cost and Efficiency Analysis of NEMO Protocol Entities Md. Shohrab Hossain, Mohammed Atiquzzaman School of Computer Science,

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Page 1: Cost and Efficiency Analysis of NEMO Protocol Entities · Cost and Efficiency Analysis of NEMO Protocol Entities Md. Shohrab Hossain, Mohammed Atiquzzaman School of Computer Science,

Cost and Efficiency Analysis of NEMO ProtocolEntities

Md. Shohrab Hossain, Mohammed AtiquzzamanSchool of Computer Science, University of Oklahoma, Norman, OK 73019, USA

Email: [email protected], [email protected]

William D. IvancicNASA Glenn Research Center, Cleveland, OH 44135, USA

Email: [email protected]

Abstract—To support IP-mobility of networks in motion, IETFproposed Network Mobility (NEMO) protocol that uses varioussignaling messages to ensure connectivity of the mobile nodeswith the Internet and to maintain security of ongoing sessions byprotecting the binding updates. As the next-generation wirelessand mobile network is supposed to be a unified network basedon all-IP technology, compounded by the fact that the numberof mobile nodes requiring mobility support has increased signifi-cantly, the cost analysis of mobility protocols and the underlyingmobility management entities have become essential to avoid theirperformance degradation. However, there has been no compre-hensive cost analysis of NEMO protocol entities that considersall possible costs. In this paper, we have developed analyticalmodels to estimate total costs of key mobility management entitiesof NEMO. We have defined a metric to compute the efficiencyof mobility protocol as well as the mobility entities to find outthe percentage of resources used for data (payload) delivery. Wehave presented numerical results to demonstrate the impact ofnetwork size, mobility rate, traffic rate and data volume on thetotal costs and the efficiency of the NEMO protocol and its keyentities. Our results show that a significant amount of resources(bandwidth, processing power, transmission power) are requiredby the mobility entities for transmission, processing of varioussignaling messages, as well as searching location database. Ourcost analysis will thus help network engineers in estimating actualresource requirements for the key entities of the network in futuredesign while analyzing the data transmission efficiencies of theseentities.

Index Terms—NEMO, mathematical modeling, cost analysis,mobility management entities, mobility protocol.

I. INTRODUCTION

To ensure continuous Internet connectivity of networks inmotion, IETF proposed NEtwork MObility Basic SupportProtocol (NEMO BSP) [1] which is an extension of IETF host-mobility protocol, Mobile IPv6 [2]. NEMO BSP requires dif-ferent mobility agents to exchange various signaling messagesto maintain continuous connectivity and security of ongoingsessions between mobile nodes and Internet nodes.

In a mobile computing environment, a number of networkparameters (such as, network size, mobility rate, traffic rate,data volume) influence the cost arising from mobility proto-cols. The total cost includes cost related to query messages,updating Home Agents about the change of location of themobile entity, sending updates to hosts with ongoing commu-nication, and processing and lookup costs by various mobility

agents. As the next-generation wireless/mobile network will bea unified network based on all-IP technology, and the numberof mobile nodes requiring mobility support has increasedsignificantly, the cost analysis of mobility protocols as wellas the underlying mobility management entities (e.g., homeagents, mobile router, etc.) have become essential to avoidperformance degradation of the mobility protocol.

There have been earlier attempts for signaling cost anal-ysis ( [3]– [10]) of host-mobility protocols, such as, MobileIPv6 [2], Hierarchical Mobile IPv6 (HMIPv6) [11]. However,these cost analysis are not adequate for NEMO protocolssince NEMO has more parameters and cost components anddifferent types of nodes in the mobile network unlike host-mobility protocols.

There have been a few works [12]– [14] on the cost analysisof NEMO protocols. However, these cost analysis ignoredmajor cost components relating to mobility management, e.g.,cost related to securing location updates, query messages byCN, obtaining IP address by MH, refreshing binding updates,costs of registration messages, etc. Hence, those analysis areincomplete. Moreover, the entity-wise evaluation of costs hasnot been performed to obtain the load on various mobilityentities of the network required for the operation of NEMOprotocol. Such analysis is very essential as resource limitationsexist for all network entities and this entity-wise evaluation canaid in estimating actual resource requirement of these entities.

The main differences of this work are that we have consid-ered all possible costs required for mobility management andhave computed total costs of various mobility managemententities of NEMO. We have also defined a metric to computethe data transmission efficiency of NEMO protocol as well asits key entities. The authors are not aware of any such work.

The objective of this work is to analyze the total cost(including data delivery cost) and data transmission efficiencyof various mobility entities of NEMO and figure out howthose costs are affected by various network parameters, suchas network size, mobility rate, traffic rate, and data volume.

The contributions of this work are: (i) developing math-ematical models to estimate total costs of various mobilitymanagement entities of NEMO: home agent for mobile router,home agent for mobile host, mobile router, correspondent

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node, mobile host, and complete network and (ii) defininga novel metric to compute the data (payload) transmissionefficacy of NEMO protocol and its key entities (iii) analyzingthe impact of network size, mobility rate, traffic rate, and datavolume on these costs and efficiency.

The analytical cost models developed in this paper coversall possible costs required for mobility management and willhelp in estimating the actual resources (bandwidth, processingpower, transmission power) required by key entities of the net-work in order to maintain continuous connectivity with remoteInternet hosts and securing the ongoing session. Moreover, theefficiency metric can be used to compare the NEMO protocoland its mobility entities with other related protocols.

The rest of the paper is organized as follows. In Section II,we present a literature review of the existing cost models ofdifferent mobility protocols. In Section III, NEMO architectureand BSP are briefly explained. In Section IV, analytical modelsfor total cost and efficiency of various entities of NEMO arepresented. Section V analyzes the results. Finally, Section VIhas the concluding remarks.

II. LITERATURE REVIEW

In this section, we present some of earlier attempts for costanalysis of mobility protocols. Xie et al. [3] perform the costanalysis of Mobile IP to minimize the signaling cost whileintroducing a novel regional location management scheme. Fuet al. [4] analyze the signaling costs of Seamless IP-diversitybased Generalized Mobility Architecture (SIGMA) [15] andHierarchical Mobile IPv6 (HMIPv6) [11]. Makaya et al. [5]present an analytical model for the performance and cost anal-ysis of IPv6-based mobility protocols (i.e., MIPv6, HMIPv6,FMIPv6 and F-HMIPv6). Diab et al. [8] propose a genericmathematical model for fast and simple cost estimation thatcan be used for a wide range of mobility management pro-tocols and the parameters of the generic model are chosento reflect the characteristics of the studied protocols, mobilitypatterns and network topologies. Galli et al. [6] propose ananalytical model for the comparative analysis of mobility pro-tocols by decomposing existing protocols into their buildingblocks, and obtaining the general cost functions to identify net-work and topology conditions under which a certain protocolperforms better than another. Singh [7] analyze the signalingcost of MIPv6 and HMIPv6 using random walk and fluid flowmodel. They use two cost components: location update costand packet delivery cost which are computed as a functionof session to mobility ratio (SMR). These cost analysis onhost mobility protocols are not adequate for NEMO protocolssince NEMO has more parameters and cost components anddifferent types of nodes in the mobile network unlike host-mobility protocols.

Munasinghe et al. [16] present an analytical signaling costmodel in a heterogeneous mobile networking environment forvertical handoffs at the core network level for a roaming user.The numerical analysis and evaluation is based on a frameworkdesigned for interworking between UMTS, CDMA2000 tech-nology, and mobile WiMAX networks. Lee et al. [17] analyze

the performance of recently proposed route optimization ofProxy Mobile IPv6, a network-based mobility support protocolproposed by the IETF, in terms of signaling cost and packetdelivery cost. Narayanan et al. [9] have analyzed varioushandoff scenarios for a dual stack mobile node roaming in amixed IPv4/IPv6 environment. They also present an analyticalmodel for the handoff signaling cost for dual stack scenario.Lee et al. [10] present an analytical cost model to evaluatethe performance of the existing IP mobility protocols, such asMobile IPv6, HMIPv6 and the recently proposed Proxy MobileIPv6 and compare them with respect to signaling cost, packetdelivery cost, tunneling cost, and total cost. Again, these worksmainly focus on host-mobility protocols.

There have been a few works on the cost analysis of NEMOprotocols. Reaz et al. [12] perform the signaling cost analysisof NEMO and SINEMO [18], seamless IP-diversity basednetwork mobility protocol. Jalil et al. [13] perform a signalingcost analysis of NEMO using the similar models developedin [12]. Lim et al. [14] perform the cost analysis of NEMOroute optimization schemes. Shahriar et al. [19] presents acost analysis framework for NEMO prefix delegation-basedschemes. However, the cost analysis performed earlier ignoredsome major costs relating to mobility management, e.g., costrelated to securing location updates, costs related to querymessages by CN, costs of refreshing binding updates, and costsof registration messages, and data acknowledgement messages,etc. These are regular and essential messages exchangedduring the operation of a mobility protocol and have significantimpact on NEMO and its mobility entities. Hence, the analysisfound in the literature are incomplete. Moreover, the entity-wise evaluation of costs has not been performed to obtain theload on various mobility entities of the network due to theoperation of NEMO protocol.

We have developed an analytical model that takes intoaccount all possible costs for mobility management. Unlikeprevious works, we have also performed the entity-wise anal-ysis to compute the actual costs and efficiencies of variouskey mobility entities involved in mobility management. Suchanalysis is very essential as resource limitations exist for all theentities responsible for mobility management in the network.This work is an extension of our earlier work [20]. We haveadded analysis and corresponding results for other network en-tities, such as on mobile hosts, correspondent nodes. We havedefined a new metric called efficiency of mobility protocolto estimate the data transmission efficacy of NEMO protocoland its key entities. We have also presented results showingefficiency of NEMO protocol and all its entities. Therefore,this work is a complete cost and efficiency analysis of NEMO.

III. NETWORK MOBILITY

In this section, we explain briefly NEMO architecture andNEMO BSP. This will aid in understanding the cost analysisof NEMO in Section IV.

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Fig. 1. NEMO Architecture

A. NEMO Architecture

Fig. 1 shows the architecture of a Mobile Network (MN).Mobile Router (MR) act as gateways for the nodes inside theMN, each of the nodes are called a Mobile Network Node(MNN). Different types of MNNs are: Local Fixed Nodes(LFN) that do not move with respect to MN, Local MobileNodes (LMN) that usually reside in MN and can move toother networks, and Visiting Mobile Nodes (VMN) that getattached to the MN from another network. LMNs and VMNsare MIPv6 capable, and we refer them as mobile nodes. TheMR attaches to the Internet through Access Routers (ARs).An MN is usually connected to a network called the homenetwork where an MR is registered with a router called theHome Agent (HA). The HA is notified the location of the MR,and re-directs packets, sent by the Correspondent Node (CN)to MNNs.

B. NEMO BSP

In NEMO BSP [1], the MR ensures connectivity of all hostsinside the MN when the MR changes its point of attachmentto the Internet while moving from a home network to a foreignnetwork. An MR has its unique IP address and one or moreMN Prefixes (MNP) that it advertises to the hosts attached toit. MR establishes a bidirectional tunnel with the HA of MobileHosts (HA-MH) to pass all the traffic between its MHs and theCNs. When MR changes its point of attachment, it acquires anew care-of-address from the visited foreign network. It thensends a Binding Update (BU) to its HA which creates a cacheentry, binding MRs home address with its care-of-address, andcreates a bidirectional tunnel between HA and MR. When aCN sends a packet to a host, the packet is routed to the HA ofthe corresponding MR (HA-MR). HA-MR looks at its cacheentry and forwards the packet to the MR using the bidirectionaltunnel. Finally, MR receives the packet, decapsulates it, andforwards it to the host inside the MN.

IV. COST ANALYSIS

We compute below the mobility management cost onNEMO’s key entities, such as, Home Agent for Mobile Router(HA-MR), Home Agent for Mobile Host (HA-MH), MobileRouter (MR) and the complete network.

A. Notations

The notations that are used the cost analysis are listed below.Nr Number of mobile routers in the mobile network,Nf Number of LFNs in the mobile network,Nl Number of LMNs in the mobile network,Nv Number of VMNs in the mobile network,Nmnn Total MNNs in the mobile network, i.e., Nmnn =

Nf +Nl +Nv,Nm Total mobile nodes in the mobile network, i.e., Nm =

Nl +Nv,Nc Average number of CNs communicating with the

nodes inside the mobile network,δL Per hop transmission cost for Location Update (LU)

message,δB Per hop transmission cost for Binding Update (BU)

message,δQ Per hop transmission cost for query message,δR Per hop transmission cost for MH registration,δDT Per hop transmission cost for each data packet,δDA Per hop transmission cost for each (data) Ack packet,δRR Per hop transmission cost for Return Routability

(RR) message,δDH Per hop transmission cost for DHCPv6 message,δTH Transmission cost for extra IP header used in tunnel-

ing,γt processing cost for tunneled packet,γr processing cost at MR,σ Proportionality constant (for transmission cost) of

wireless link over wired link,ψ Linear coefficient for lookup cost,Tr Subnet residence time,λs Average session arrival rate,hp average number of hops between Internet to arbitrary

CN, HA or AR,hin average number of hops in the Internet,ωl Ratio of number of LMNs to total MNNs in the MN,ωf Ratio of number of LFNs to total MNNs in the MN,ωv Ratio of number of VMNs to total MNNs in the MN,κ Maximum transmission unit,α Average session size.

B. Assumptions

Following are the assumptions of the model:• All the MRs have the same HA which is HA-MR.• HA-MR is the HA for LFNs and LMNs of the mobile

network under consideration.• HA-MH has been considered to be HA of all the VMNs

of the mobile network under consideration. That is, HA-MH serves as the location manager of Nf mobile hosts.

• Session arrival rate for each mobile host is equal.

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• The data (file) size in each session is equal.• Each CN has, on the average, one ongoing session with

a MNN.• Binary search is used to search location database.

C. User Mobility Model

Most of the cost analysis ( [3], [4], [12]) used random way-point model as the user mobility model though the mobilitypattern simulated by the RWP model is not realistic. We haveused city section mobility model, a realistic street movementmodel, as the mobility model. The stochastic properties ofCSM model has been analyzed in [21] and we use theexpression of subnet residence time in Section V for numericalanalysis.

D. Traffic Model

Session arrival follows Poisson process with the followingprobability distribution function:

fs(n) =e−λsλnsn!

(1)

In other words, the inter-arrival times are exponentiallydistributed. The session length process that denotes size of data(file) in each session follows Pareto distribution. The meansession length (file size) is assumed to be α.

E. HA-MR

In NEMO, the HA-MR keeps the location database of themobile network. In fact, the location information of MR, LFNsand LMNs are kept in the HA-MR whereas that of VMNs arekept in corresponding HAs since they belong to some othernetworks. The main tasks of HA-MR are processing 1) querymessages from CNs, 2) LU messages from MRs, 3) RR testmessages, 4) BU messages to CNs, and 5) data delivery cost.

1) Query message: The fraction of CNs that communicatewith either with a LMN or a LFN are (ωl + ωf )Nc. TheseCNs send query message to the HA-MR at the beginning ofevery session. This requires a lookup at the HA-MR which isproportional to the logarithm of the number of entries in thelookup table. As the HA-MR contains location information forall the MRs, LFNs and LMNs (see the assumption above), thelookup cost at HA-MR is ΨLK

HA−MR = ψ log2(Nr + Nf +

Nl). In addition, transmission cost is incurred for query-replymessages at the HA-MR. Hence, the cost relating to querymessages at HA-MR are given by the following equation:

ΛQRHA−MR = (ωl + ωf )Ncλs

[2δQ +ΨLK

HA−MR

](2)

2) Location update messages: When the mobile networkcrosses subnets, MR sends LU message to the HA-MR andthe location database is modified by the HA-MR which sendsback acknowledgement to LU message. This happens in everyTr seconds. In addition, MRs and mobile nodes send periodicrefreshing updates to the HA-MR so that the entries are notremoved from the the location database after the binding life-time. Let the lifetime of the entries in the location database be

Te. Therefore,⌊Tr

Te

⌋refreshing updates will be sent to HA-MR

within the time Tr. Thus, the frequency of sending periodicrefreshing updates are ηr =

⌊Tr

Te

⌋/Tr, and total frequency of

sending LU and refreshing LU is ηt =(1 +

⌊Tr

Te

⌋)/Tr,

Each LU and corresponding Acknowledgement messagesexchanged with HA-MR incurs transmission and processingcost. The LU messages from LMNs goes through one level ofencapsulation which cost additional transmission cost of δTH

and a processing cost of γt. whereas the LU messages fromthe MR goes without encapsulation. In both cases, a lookupcost of ΨLK

HA−MR is required. So the cost related to the LUand refreshing LU messages can be computed as follows:

ΛLUHA−MR = ηtNr

[2δL +ΨLK

HA−MR

]+ ηrNl

[2(δL + δTH + γt) + ΨLK

HA−MR

] (3)

3) Return routability messages: NEMO employs RR testbefore sending BU to the HA similar to the mechanismemployed in route optimization of MIPv6 [2]. Before eachBU message, RR messages are exchanged among the MR,HA and CN. The HA-MR receives the Home Test Init (HoTI)message sent by the MR and forwards it to the CN. HA-MR also receives the Home Test (HoT) message from the CNand sends it back to MR. This happens for every Tr seconds.The HA-MR receives these RR messages for all CNs that arecommunicating with LMN. Therefore, the cost on HA-MR forRR messages are as follows:

ΛRRHA−MR = Nl

(Nc

Nmnn

)4δRR

Tr

(4)

4) Binding updates to CNs: To continue ongoing sessionswith the CNs, LMNs inside the mobile network sends refresh-ing Binding Updates (BU) to the CNs by tunneling throughthe HA-MR. The HA-MR has to lookup the table, tunnel andtransmit those BUs. Hence, cost incurred on HA-MR due theseBUs are given by,

ΛBUHA−MR = 2ωlNcηr

[δB + δTH + γt +ΨLK

HA−MR

](5)

5) Data delivery cost: In every session, the first data packetis sent through the HA and all other packets are transmittedthrough direct path to the MR [2]. This is also true for VMNs.Data packets (first one of each session) are routed though theHA-MR. This costs transmission cost data and ACK packets,extra IP-header processing and transmission cost as well aslookup cost. Therefore, the data delivery cost on the HA-MRis given by,

ΛDDHA−MR = Ncλs

[δDT + δDA + 2

(δTH + γt +ΨLK

HA−MR

)](6)

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6) Total cost: Thus, the total cost of the HA-MR can beobtained by adding Eqns. (2), (3), (4) (5), and (6):

ΛHA−MR = ΛQRHA−MR + ΛLU

HA−MR + ΛRRHA−MR

+ ΛBUHA−MR + ΛDD

HA−MR

(7)

F. HA-MH

The HA-MH serves as the location manager of the VMNsof the mobile network. The main tasks of the HA-MH are 1)processing the query message sent by the CNs, 2) processingthe LU messages, 3) RR messages of the VMNs, and 4) datadelivery cost.

1) Query message: The fraction of CNs that communicatewith the VMN are ωvNc and they send query message tothe HA-MH at the beginning of every session. This incurstransmission and lookup cost for HA-MH. Thus, cost on HA-MH for query messages is

ΛQRHA−MH = ωvNcλs

[2δQ + ψ log

2Nv

](8)

2) Location update messages: Each VMN sends LU mes-sage after each handoff and periodic refreshing updates to theHA-MH which incurs transmission, and lookup cost. Thus thecost on HA-MH is

ΛLUHA−MH = Nvηt

(2(δL + δTH + γt) + ψ log

2Nv

)(9)

3) Return routability messages: Each VMN sends RRmessages involving the HA-MH which costs the following:

ΛRRHA−MH = Nv

(Nc

Nmnn

)4δRR

Tr

(10)

4) Data delivery cost: The first data packet from the CNtravel through the HA-MH, and then through the HA-MR toreach the VMN. This requires transmission, extra IP-headerprocessing and lookup cost at HA-MH. Therefore, the datadelivery cost on the HA-MH is given by

ΛDDHA−MH = ωvNcλs

[δDT + δDA

+ 2(δTH + γt + ψ log

2Nv

)] (11)

5) Total cost: Thus, the total cost of the HA-MR can beobtained by adding Eqns. (8), (9), (10), and (11):

ΛHA−MH = ΛQRHA−MH + ΛLU

HA−MH + ΛRRHA−MH + ΛDD

HA−MH (12)

G. Mobile RouterIn NEMO, the main tasks of each MR are 1)IP address and prefix

acquisition, 2) sending LU messages to HA-MR, 3) sending bindingupdates to the CNs, 4)processing RR messages, and 5) processingdata (ACK) packets to and from MNNs,

1) Acquiring IP address and prefixes: MRs acquire IP addressfrom access router in the foreign network during each handoff byexchanging DHCPv6 request-reply messages through the wirelessmedia.

ΛDHCPMR =

2σδDH

Tr

(13)

2) Location updates: After each handoff, each MR sends a LUmessage to the HA-MR. In addtion, periodic refreshing updates arealso sent by the MRs and the mobile nodes through MR. Thus thecost on each MR due to LU messages is,

ΛLUMR = 2σηtδL + 2ηr

(Nm

Nr

)(σ(δL + δTH) + γt

)(14)

3) Binding updates to CNs: Mobile nodes send periodicrefreshing BUs to the CNs through the MR updating thecurrent address to continue ongoing sessions. Number of CNsthat communicates with the mobile nodes are Nc(ωl + ωv).This requires transmission of BU message through the wirelessmedia with extra IP-header (encapsulation), and processingcost due to tunneling. Thus the cost on each MR for these BUmessages are

ΛBUMR = 2ηr

(Nc

Nr

)(ωl + ωv)

(σ(δB + δTH) + γt

)(15)

4) MH’s local registration messages: Every subnet crossingby the MH (in every Tl sec from a MR region) triggers alocal registration message to be sent to the MR. This involvestransmission cost over the wireless link and processing cost atMR.

ΛLRMR =

Nm

Nr

×

2σδR + γrTl

(16)

5) Return routability messages: To ensure that the ongoingsession is not hijacked by some malicious agent, beforesending binding updates to the HA-MR, it is essential toperform RR test to verify that the node can actually respondto packets sent to a given CoA [2]. Thus the MR will haveto process and transmit RR messages on behalf of the mobilenodes under its domain.

ΛRRMR =

4σ(Nm/Nr)δRR

Tr

(17)

6) Data delivery cost: In each session between the CN andMNN, an average of �α

κ� data packets are sent from the CN

to MNN or vice versa. The successful reception of each datapacket is confirmed by a corresponding ACK packet from thereceiver. As each MR manages the ongoing communicationof Nc/Nr sessions, total data / ACK packet arrival rate tothe MR is λp = (Nc/Nr)λs�

ακ�. Data packet delivery incurs

transmission cost through the wireless media (with extra IP-header), and processing cost for the MR. Therefore, the datadelivery cost at each MR is given by,

ΛDDMR = λp

(σ(δDT + δDA + δTH) + γt

)(18)

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7) Total cost: Therefore, total cost of each MR can beobtained by adding Eqns. (13), (14), (15), (17), and (18),

ΛMR = ΛDHCPMR + ΛLU

MR + ΛBUMR +ΛLR

MR + ΛRRMR + ΛDD

MR (19)

H. Mobile Host

As the mobile nodes inside a mobile network can movewithin the network, they can be attached to a new MR leavingthe domain of a previous mobile network. As the mobile nodesinside the network do not have to send binding updates to theCNs, rather the MR does so on their (MHs’) behalf, reducingthe signaling load on the MHs. In fact, the MRs analyzesthe sessions between the MHs and the CNs, and updates thesessions table which is used to send binding updates to theCNs. Thus, the cost on each MH is for registration with theMR and data delivery directly to the CN through the MR.

1) Registration messages: When a MH enters into a MRdomain, it receives router advertisements, and registers withthe MR sending (receiving) registration request (reply). Letthe time duration that a MH reside within a MR be Tl.So the subnet change frequency for the MH (micro-mobilityinside the MN) is 1/Tl. Therefore, the overhead on each MHassociated with the registration event is given by

ΛRGMH =

2σδRTl

(20)

2) Data delivery cost: We have assumed a total of Nc

CNs for all the (Nf + Nm) MNNs. Therefore, on the av-erage, number of correspondent node per MNN or MH isNc/(Nf + Nm) = Nm

c (let). Thus, Each MH communicateswith Nm

c correspondent nodes through MRs. Since averagesession length is α, total number of packets in a session is⌈ακ

⌉. Therefore, the packet delivery costs for each MH per

second is as follows:

ΛDDMH = Nm

c

⌈ακ

⌉σλs(δDT + δDA) (21)

3) Total cost of each MH: Thus, the total signaling over-head on each HA can be obtained by adding Eqns. (20), and(21) as

ΛMH = ΛRGMH +ΛDD

MH (22)

I. Correspondent Node

The total cost of each CN are due to the query messageexchanged with CLM, RR messages and data delivery cost.

1) Query message: Each CN sends query messages to theHA for each association with the MH. Since the session arrivalrate is λs, the transmission cost per second on CN for thisquery message is

ΛQRCN = 2δQλs (23)

2) Return routability messages: Every CN processes returnroutability messages sent by the MH so that malicious hostscannot steal a session. So the cost on CN is given by,

ΛRRCN =

4δRR

Tr

(24)

3) Data delivery cost: In each session, a file of size α istransferred from the CN to the MH. Since session arrival rateis λs, then packet delivery cost on CN per unit time can beobtained as

γDDCN = λs

⌈ακ

⌉(δDT + δDA) (25)

4) Total Cost on each CN: Therefore, the total cost on eachCN can be obtained by adding Eqns. (23), (24) and (25):

ΛCN = ΛQRCN + ΛRR

CN + ΛDDCN (26)

J. Complete Network

In order to compute the signaling load on the network asa whole, we consider all the resources (such as, bandwidth,processing power, etc.) consumed in all network entities. Thecost of the network due to the operation of NEMO BSPinclude query messages exchanged between HA and CN, localregistration of MHs, RR messages, location update messages,binding updates to CNs, and data delivery to CN.

1) Query message: At the beginning of each session be-tween a MNN and a CN, query messages are exchangedbetween CN and HA (HA-MR or HA-MH). As the sessionarrival rates for each MNN are assumed to be equal (λs), thetransmission cost for all the query and reply messages towardsthe HA-MR or HA-MH is 2Nc(hp + hin + hp)δQλs. Thesearching cost in the HA-MR is (ωl + ωf )Ncψλs log2(Nr +Nl + Nf ) and that in HA-MH is ωvNcψλs log2Nv. Hence,the cost of the network for the query messages from the CNsis,

ΛQRNet = λsNc

[2δQ(2hp + hin) + ψ(ωl + ωf )

× log2(Nr +Nl +Nf ) + ψωv log2

Nv

] (27)

2) Local registration messages: Every subnet crossing bythe MH (in every Tl sec) within a MR region, triggers alocal registration message to be sent to the MR. This involvestransmission cost in one wireless hop. In addition, processingcost is incurred at the MR for updating the local locationdatabase.

ΛLRNet = Nm

2σδR + γrTl

(28)

3) Return routability messages: The RR messages are sentevery Tr second by the MRs (on behalf of the MNNs) to HA(either HA-MR or HA-MH) which forwards them to CN. TheHoTI message follow the path between MR and HA whichconsists of (hp + hin + hp) wired hops with one wireless hop(between the MR and the AR). The path between HA and CNcontains (hp + hin + hp) wired hops. Similar cost is incurredfor each HoT message. Each CoTI message is sent directlyto CN from the MR which uses (hp + hin + hp) wired hopsand one wireless hop. Therefore, cost on the network for RRmessages are as follows:

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ΛRRNet = 2δRR

((hp + hin + hp + σ) + (hp + hin + hp)

+ (hp + hin + hp + σ))×

Nc

Tr

(29)

4) Location updates: After each handoff, each MRs andLMNs send LU to the HA-MR and VMNs send LU to HA-MH informing the newly acquired IP address and prefixes.As the HA is (hp + hin + hp + 1) hops (including hpwireless hop) away from the MR, each LU from MR (andcorresponding Ack) message incurs a transmission cost ofδL(hp+hin+hp+σ), and a lookup cost of ΨLK

HA−MR at theHA-MR. The LU messages from LMNs (or VMNs) travels onemore wireless hop than the MR with additional transmissioncost for tunneling header and tunnel processing cost. Thus thecost of LU message on the network is given by,

ΛLUNet = 2NrδLηt(hp + hin + hp + σ) + 2(Nl +Nv)ηr

×

((δL + δTH )(hp + hin + hp + 2σ) + γt

)+ (ηtNr + ηrNl)Ψ

LKHA−MR + ηtNvψ log

2Nv

(30)

5) Binding updates to CNs: To maintain continuous con-nectivity with the CNs that are communicating with themobile nodes, binding updates informing the care-of-addressare sent to the CNs. These BU messages goes through and(hp + hin + hp) wired hops and two wireless hop, on theaverage, to reach a CN. Thus cost required to send BU toCNs are given by,

ΛBUNet = 2Ncηr(ωl + ωv)

[(hp + hin + hp + 2σ)

× (δB + δTH) + γt] (31)

6) Data delivery cost: The first data packet in a sessiongoes through the HA (with tunneling) whereas the rest of thepackets, that is,

(⌈ακ

⌉− 1

)packets use direct route (without

tunneling). The path between a MNN and the HA contains(hp + hin + hp) wired links and 2 wireless links whereas thepath between HA and CN contains (hp + hin + hp) wiredlinks. In addition, data packets incur table lookup in HA-MR and HA-MH. Thus, the costs related to data delivery andprocessing by the network are given by

ΛDDNet = λsNc

[((hp + hin + hp + 2σ) + (2hp + hin)

)× (δDT + δDA + 2δTH ) + 2γt + 2ωvψ log

2Nv + 2ΨLK

HA−MR

]

+Ncλs

(⌈ακ

⌉− 1

)[((hp + hin + hp + 2σ)

)(δDT + δDA)

] (32)

7) Total cost of the network: Therefore, the total cost ofthe complete network due to NEMO protocol can be obtainedby adding Eqns. (27), (28), (29), (30), (31), and (32),

ΛNet = ΛQRNet + ΛLR

Net + ΛRRNet + ΛLU

Net + ΛBUNet + ΛDD

Net (33)

K. Efficiency

In this section, we define a new metric (efficiency) for themobility protocol as well as the entities of the network.

a) NEMO protocol: Efficiency of a NEMO protocol isdefined as the ratio of data delivery cost (when an optimalroute is used) to the total cost (that includes signaling and datadelivery costs) required for the mobility protocol. In NEMOBSP, the data packets are sent through the HA even thoughit is not the optimal route. The cost to send data from CN toMH in the optimal route can be obtained as follows:

ΛDD = Ncλs

⌈ακ

⌉(hp + hin + hp + 2σ)δDT (34)

Therefore, efficiency of NEMO BSP can be obtained usingthe following equation:

ζNEMO =ΛDD

ΛNet

(35)

b) Mobility entities: We define efficiency of an entity asthe percentage of usage of its resources due to the transmissionof payload (data). Thus the efficiency of HA-MR can beobtained as follows:

ζHA−MR =NcλsδDT

ΛHA−MR

(36)

Similarly, we can compute the efficiencies of HA-MH, MR,MH and CN using the following equations:

ζHA−MH =ωvNcλsδDT

ΛHA−MH

(37)

ζMR =σλpδDT

ΛMR

(38)

ζMH =Nm

c σλs

⌈ακ

⌉δDT

ΛMH

(39)

ζCN =λs

⌈ακ

⌉δDT

ΛCN

(40)

V. RESULTS

In this section, we present numerical results to demonstratethe impact of network size, mobility rate, traffic rate and datavolume on the total cost of various mobility managemententities. The default values of the parameters used to obtain thenumerical results are shown in Table ???. We have considereda large mobile network with the number of MNNs around270 which is common onboard a train or ship. Values of theparameters related to the file-size, packet-size, session arrivalrates and the proportionality constant for the wireless networkare taken from [12], [22]. Transmission costs are relative anddetermined based on the packet size assuming unit cost per100 bytes. Similarly, processing costs are determined assumingunit cost per 100 bytes. The transmission and processing costsare determined following the technique used in [19], [32]. Forthe lookup cost, we assume a logarithmic time for the lookup

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with the proportionality constant as the processing cost perentry.

The values for the system parameters have been taken fromthe previous works [12], [22]: δL = 0.6, δB = 0.6, δQ = 0.6,δR = 0.6, δDH = 1.4, δRR = 0.6, δDT = 5.72, δDA = 0.60,δTH = 0.40, σ = 10, λs = 0.01, γt = 10, Nc = Nmnn, hin=5, hp= 1, Tr = 70s, Te = 60s, ψ = 0.3, α = 10Kb, and κ =576b, Nr = 20, Nf = 70, Nl = 100, Nv = 100; Nm = 200;

A. Total cost on HA-MR

In Fig. 2(a), the total cost of the HA-MR is shown forvarying number of mobile hosts and different subnet residencetimes. Here we have used equal number of LMNs and VMNs,that is, Nv = Nl =

1

2Nm. and the values used for Nf and Nr

are 100 and 20, respectively. It is found that total cost of HA-MR increases for higher number of mobile hosts and higherresidence times. For NEMO, when the subnet residence timeincreases the refreshing binding cost increases although thecost related to handoff reduces due to less handoff frequency.Other costs, such as, query and data delivery cost remainsunchanged. The net result is increase of total cost. It can benoted that refreshing BU is dependent on the values of Tr andTe. For Te = 60 sec and Tr = 50 sec, there will be no needof refreshing BU, whereas for Tr = 100 and Tr = 150, thenumber of times RBU sent by mobile hosts (while residing ina subnet) are 1 and 2, respectively.

In Fig. 2(b), the total cost of the HA-MR is shown as afunction of Session to Mobility Ratio (SMR) which is definedas λs×Tr. We keep λs constant while varying the value of Trbetween 50 to 400 sec. Increase of SMR value implies highersubnet residence times of the mobile network, producing lesssignaling relating to location updates and refreshing bindingupdates. In addition, the presence of higher number of MRsresults in more LUs, thus increasing the total cost of HA-MR.

B. Total cost on HA-MH

Fig. 3(a) shows the impact of number of VMNs on thetotal cost of HA-MH. We have varied total number of CNscommunicating with the MNNs for this graph. As number ofVMNs increases in the mobile network, data packets are sentthrough the HA-MH along with higher number of LU andRR messages. In addition, higher number of CNs implies inhigher query messages exchanged between HA-MH and CN,thus producing higher cost for HA-MH.

Fig. 3(b) shows the impact of SMR on the total cost of theHA-MH for different number of VMNs. Total cost decreaseswith higher SMR values (that is, when mobility rate of MN islow). The changes of total cost is very small as the total costis dominated by the data delivery cost which is independentof subnet residence time.

C. Total cost on each MR

In Fig. 4(a), the total cost of each MR is shown for varyingnumber of mobile hosts and LFNs. Increase in LFNs resultsin constant shifting of the total cost graph due to the increasein query message cost and data delivery cost. In Fig. 4(b),

100 200 300 400 500 600 7000

100

200

300

400

500

600

Tot

al C

ost o

n H

A−

MR

Number of Mobile Hosts

Tr = 50s

Tr = 100s

Tr = 150s

(a)

0.5 1 1.5 2 2.5 3 3.5 4205

210

215T

otal

Cos

t on

HA

−M

R

Session to Mobility Ratio (SMR)

Nr = 20

Nr = 30

Nr = 40

(b)

Fig. 2. (a) Impact of number of mobile hosts on the total cost on the HA-MRfor different subnet residence times and (b) Impact of SMR on the total costof the HA-MR for different number of MRs.

the impact of SMR on the total cost of each MR is shownfor varying session lengths. Higher session length causes moredata packets to be routed through each MR, resulting in highercost. The total cost is found to be invariant of SMR due tothe dominance of data delivery cost.

D. Total cost on each MH

In Fig. 5(a), the total cost of each MH is shown for varyingnumber of CNs communicating with it and for differentsession lengths. Increase in number of CNs per MH results inhigher data delivery cost, thereby producing more cost on theMH. Similar thing happens for higher values session lengths.In Fig. 5(b), the impact of SMR on the total cost of each MHis shown for various Tl, i.e, the subnet residence time of a MHunder a MR-region in the mobile network. Higher values ofTl produces less registration messages, thereby reducing thetotal cost. The total cost is found to be invariant of SMR dueto the dominance of data delivery cost in each MH.

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50 100 150 20050

100

150

200

250

300

Tot

al C

ost o

n H

A−

MH

Number of Visiting Mobile Nodes

Nc = 300

Nc = 450

Nc = 600

(a)

0.5 1 1.5 2 2.5 3 3.5 440

60

80

100

120

140

160

180

200

220

Tot

al C

ost o

n H

A−

MH

Session to Mobility Ratio (SMR)

Nv = 50

Nv = 100

Nv = 150

(b)

Fig. 3. (a) Impact of number of VMNs on the total cost of the HA-MH fordifferent number of CNs, (b) Impact of SMR on the total cost of the HA-MHfor different number of VMNs.

E. Total cost on each CN

In Fig. 6(a), the total cost of each CN is shown for varyingsession arrival rates and session lengths. Higher session arrivalrates causes more query messages to be sent to the CN,resulting in the increase of total cost on each CN. Highersession lengths causes higher packet delivery costs, therebygenerating higher cost on each CN.

In Fig. 6(b), the total cost of each CN is shown for varyingsubnet residence times and session arrival rates. The total costincreases for higher session arrival rates, as the CN sendsmore query messages to the HA, in addition to the higher datadelivery cost. However, the total cost on each CN reduces veryslowly with higher subnet residence times, as the magnitudeof lower return routability cost is not quite visible due to themore dominant data delivery cost.

100 200 300 400 500 600 700100

200

300

400

500

600

700

800

Tot

al C

ost o

n ea

ch M

R

Number of Mobile Hosts

Nf = 100

Nf = 200

Nf = 300

(a)

0.5 1 1.5 2 2.5 3 3.5 40

500

1000

1500

2000

2500T

otal

Cos

t on

each

MR

Session to Mobility Ratio (SMR)

α = 10kα = 50kα = 100k

(b)

Fig. 4. (a) Impact of number of mobile hosts on the total cost of each MRfor different number of LFNs, (b) Impact of SMR on the total cost of eachMR for different session lengths.

F. Cost on Complete Network

Fig. 7(a), the total cost of the complete network is shownas function of number of mobile hosts. We have used equalnumber of LMN and VMNs for this graph. Increased numberof mobile hosts sends higher number of location updates,binding updates; in addition, query for the mobile hosts arealso increased for higher number of mobile hosts in the MN.The total cost is also shown for different number of hops inthe Internet (such as, hin = 5, 15 and 25). The slope of thetotal cost graph rises for higher values of hin since its valueof influences all the costs of the network.

In Fig. 7(b), total cost of the network is shown as a functionof SMR for different session length. It is found that the totalcost does not vary much (around 1%) with respect to SMR.This implies that data delivery cost (through optimized andunoptimized route) dominates the total cost.

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2 4 6 8 100

200

400

600

800

1000

1200

Tot

al C

ost o

n ea

ch M

H

Number of CNs per MH

α = 10kα = 50kα = 100k

(a)

0.5 1 1.5 2 2.5 3 3.5 456.85

56.9

56.95

57

57.05

57.1

57.15

Tot

al C

ost o

n ea

ch M

H

Session to Mobility Ratio (SMR)

Tl = 50 sec

Tl = 100 sec

Tl = 150 sec

(b)

Fig. 5. (a) Impact of number of CNs per MH on the total cost of each MHfor different session lengths, (b) Impact of SMR on the total cost of each MHfor subnet residence times inside a MR-region.

G. Efficiency of NEMO

Fig. 8(a), the efficiency of NEMO is shown for varyingnumber of mobile hosts in the network with different numberof hops in the Internet. Increased number of mobile hostscauses higher signaling costs, such as, location updates, bind-ing updates, query cost. Hence the efficiency drops for highernumber of nodes. Moreover, with more number of Internethops, these signaling costs increases, thereby producing lowerefficiency of NEMO.

In Fig. 8(b), the efficiency of NEMO is shown as a functionof SMR for different session lengths. Higher session lengthscauses higher efficiency of NEMO due to higher data volume.On the other hand, higher SMR (i.e., lower speed of MN)causes less signaling traffic, thereby causing higher efficiency.

0.02 0.04 0.06 0.08 0.10

20

40

60

80

100

120

Tot

al C

ost o

n ea

ch C

N

Session arrival rates

α = 10kα = 50kα = 100k

(a)

50 100 150 200 250 300 350 4000

2

4

6

8

10

12T

otal

Cos

t on

each

CN

Subnet Residence Times (sec)

λs = 0.01

λs = 0.05

λs = 0.1

(b)

Fig. 6. (a) Impact of session arrival rates on the total cost of each CN fordifferent session lengths, (b) Impact of subnet residence times on the totalcost of each CN for different session arrival rates.

H. Efficiency of HA-MR

Fig 9(a) shows the efficiency of HA-MR as a function ofnumber of MHs for various subnet residence times. As wecan see that the efficiency of HA-MR is much less than thatof the NEMO protocol (see Fig. 8(a)) since HA-MR is highlyinvolved in signaling which makes its (data) efficiency muchless than the network. The pattern of this graph is similar toFig. 8(a).

In Fig. 9(b), the efficiency of HA-MR as a function of SMRfor different number of MRs in the network. Higher numberof MRs produces more binding updates and refreshing bindingupdates, thereby reducing the efficiency. Moreover, the higherSMR value produces higher efficiency due to lower signalingtraffic.

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100 200 300 400 500 600 7000.5

1

1.5

2

2.5

3

3.5

4

4.5

5x 10

4

Tot

al C

ost o

n th

e N

etw

ork

Number of Mobile Hosts

hin

= 5

hin

= 15

hin

= 25

(a)

0.5 1 1.5 2 2.5 3 3.5 40

1

2

3

4

5

6

7

8

9x 10

4

Tot

al C

ost o

n th

e N

etw

ork

Session to Mobility Ratio (SMR)

α = 10kα = 50kα = 100k

(b)

Fig. 7. (a) Impact of number of mobile hosts on the total cost of the networkfor different number of hops in Internet, (b) Impact of SMR on the total costof the network for different session lengths.

I. Efficiency of HA-MH

Fig. 10 shows the efficiency of HA-MH as a function ofVMNs for different number of CNs. Higher values of Nc

more query messages, and return routability message, therebyreducing the efficiency. With the increase of number of VMNs,the magnitude of signaling cost rises at a higher rate than thedata delivery cost, producing lower efficiency of HA-MH. Itcan be noted that the efficiency of HA-MH is somewhat closerto that HA-MR as both serve as the HA of the nodes insidethe mobile netowrk.

J. Efficiency of each MR

Fig. 11 shows the efficiency of each MR as a functionof SMR for different session lengths. Higher session lengthsproduce higher (data) efficiency. In addition, the higher valueof SMR (less mobility) causes efficiency to increase due toless signaling

100 200 300 400 500 600 700

0.78

0.785

0.79

0.795

0.8

0.805

0.81

Eff

icie

ncy

of N

EM

O

Number of Mobile Hosts

hin

= 5

hin

= 15

hin

= 25

(a)

0.5 1 1.5 2 2.5 3 3.5 40.78

0.8

0.82

0.84

0.86

0.88

0.9E

ffic

ienc

y of

NE

MO

Session to Mobility Ratio (SMR)

α = 10kα = 50kα = 100k

(b)

Fig. 8. (a) Efficiency of NEMO vs. number of MHs for different numberof hops in Internet, (b) Efficiency of NEMO vs. SMR for different sessionlengths.

K. Efficiency of each MH

Fig. 12 shows the efficiency of each MH as a function ofnumber of CNs (per MH) for different session lengths. Highervalues of CNs and higher session lengths causes more datatraffic in the network, thereby increasing the efficiency.

L. Efficiency of each CN

In Fig. 13, the efficiency of each CN is shown as a functionof subnet residence times for various session arrival rates.Higher subnet residence times cause less signaling traffic,thereby producing higher efficiency. For λs, the opposite istrue.

M. Discussion on Results

We have analyzed the impact of network size (number ofMHs, LFNs, MRs), mobility rate (subnet residence times,

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100 200 300 400 500 600 7000.08

0.1

0.12

0.14

0.16

0.18

Eff

icie

ncy

of H

A�

MR

Number of Mobile Hosts

Tr = 50s

Tr = 100s

Tr = 150s

(a)

0.5 1 1.5 2 2.5 3 3.5 40.079

0.08

0.081

0.082

0.083

0.084

Eff

icie

ncy

of H

A�

MR

Session to Mobility Ratio (SMR)

Nr = 20

Nr = 30

Nr = 40

(b)

Fig. 9. (a) Efficiency of HA-MR vs. number of MHs for different subnetresidence times, (b) Efficiency of NEMO vs. SMR for different number ofMRs.

SMR), traffic rate (session arrival rate), and data volume(session length) on the total costs and efficiencies of variousmobility entities of NEMO protocol. It is found that totalcost on various entities increases for smaller session lengthas there is more signaling traffic compared to data traffic. Inaddition, the cost on various entities does not vary much withrespect to session to mobility ratio due to the dominance ofdata delivery cost over signaling costs. The efficiency of theNEMO protocol is found to be much higher than that of homeagents (HA-MR and HA-MH) as these entities manage mostof the mobility signaling whereas the efficiencies of mobilehosts and correspondent nodes are much higher due to theirless involvement in signaling.

VI. CONCLUSION

In this paper, we have developed mathematical modelsto estimate the total costs and data transmission efficiencies

50 100 150 2000.04

0.05

0.06

0.07

0.08

0.09

0.1

Eff

icie

ncy

of H

A�

MH

Number of Visiting Mobile Nodes

Nc = 300

Nc = 450

Nc = 600

Fig. 10. Efficiency of HA-MH vs. number of VMNs for different numberof CNs.

0.5 1 1.5 2 2.5 3 3.5 40.67

0.68

0.69

0.7

0.71

0.72

0.73

0.74

Eff

icie

ncy

of e

ach

MR

Session to Mobility Ratio (SMR)

α = 10kα = 50kα = 100k

Fig. 11. Efficiency of MR vs. SMR for different session lengths.

2 4 6 8 10

0.86

0.87

0.88

0.89

0.9

0.91

Eff

icie

ncy

of e

ach

MH

Number of CNs per MH

α = 10kα = 50kα = 100k

Fig. 12. Efficiency of MH vs. number of CNs for different session lengths.

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50 100 150 200 250 300 350 4000.85

0.86

0.87

0.88

0.89

0.9

Eff

icie

ncy

of e

ach

CN

Subnet Residence Times (sec)

λs = 0.01

λs = 0.05

λs = 0.1

Fig. 13. Efficiency of CN vs. subnet residence times for different sessionarrival rates.

of various mobility management entities of NEMO BSP,considering all possible costs that influence their operation.We have presented numerical results to show the impact ofnetwork size, mobility rate, traffic rate, and data volume onthe total costs and efficiencies of these mobility entities aswell as the NEMO protocol. The cost analysis presented inthis paper will help network engineers in estimating actualresource requirements for the key entities of the network infuture design and can be used to compare with other mobilityprotocols.

REFERENCES

[1] V. Devarapalli, R. Wakikawa, A. Petrescu, and P. Thubert, “ NEtworkMObility (NEMO) basic support protocol,” RFC 3963, Jan 2005.

[2] D. Johnson, C. E. Perkins, and J. Arkko, “ Mobility support in IPv6,”IETF RFC 3775, Jun 2004.

[3] J. Xie and I. Akyildiz, “A novel distributed dynamic location man-agement scheme for minimizing signaling costs in Mobile IP,” IEEETransactions on Mobile Computing, vol. 1, no. 3, pp. 163– 175, Jul 2002.

[4] S. Fu and M. Atiquzzaman, “ Signaling cost and performance of SIGMA:A seamless handover scheme for data networks,” Wireless Communica-tion and Mobile Computing, vol. 5, no. 7, pp. 825– 845, Nov 2005.

[5] C. Makaya and S. Pierre, “An analytical framework for performanceevaluation of IPv6-based mobility management protocols,” IEEE Trans-actions on Wireless Communications, vol. 7, no. 3, pp. 972– 983, Mar2008.

[6] S. Galli, A. McAuley, and R. Morera, “An analytical approach to theperformance evaluation of mobility protocols: The overall mobility costcase,” in IEEE International Symposium on Personal, Indoor and MobileRadio Communications (PIMRC), Barcelona, Spain, Sept 5-8, 2004.

[7] B. Singh, “ Signaling cost analysis in mobile IP networks,” in IETConference on Wireless, Mobile and Multimedia Networks, Mumbai,India, Jan 11-12, 2008.

[8] A. Diab, A. Mitschele-Thiel, and F. Liers, “ Estimation of the cost result-ing from mobility management protocols using a generic mathematicalmodel,” in ACM International Conference on Modeling, Analysis, andSimulation of Wireless and Mobile Systems, Vancouver, BC, Canada,Oct 27-31, 2008.

[9] J. Xie and U. Narayanan, “ Performance analysis of mobility support inIPv4/IPv6 mixed wireless networks,” IEEE Transactions on VehicularTechnology, vol. 59, no. 2, Feb 2010.

[10] J.-H. Lee, T. Ernst, and T.-M. Chung, “ Cost analysis of IP mobilitymanagement protocols for consumer mobile devices,” IEEE Transactionson Consumer Electronics, vol. 56, no. 2, May 2010.

[11] H. Soliman, C. Castelluccia, K. E. Malki, and L. Bellier, “ HierarchicalMobile IPv6 mobility management (HMIPv6),” IETF RFC 5380, Oct2008.

[12] A. S. Reaz, P. K. Chowdhury, and M. Atiquzzaman, “ Signaling costanalysis of SINEMO: Seamless End-to-End Network Mobility,” in FirstACM/IEEE International Workshop on Mobility in the Evolving InternetArchitecture, San Francisco, CA, Dec 1, 2006.

[13] K. A. Jalil and J. Dunlop, “ Signaling cost analysis of PDE-NEMO,”in World Congress on Science, Engineering and Technology, Penang,Malaysia, Feb 25-27, 2009.

[14] H. Lim, D. Lee, T. Kim, and T. Chung, “A model and evaluation ofroute optimization in nested NEMO environment,” IEICE Transactionon Communications, vol. E88-B, no. 7, pp. 2765– 2776, Jul 2005.

[15] S. Fu and M. Atiquzzaman, “ SIGMA: A Transport Layer HandoverProtocol for Mobile Terrestrial and Space Networks,” e-Business andTelecommunication Networks, Springer, pp. 41– 52, 2006.

[16] K. S. Munasinghe and A. Jamalipour, “Analysis of signaling cost fora roaming user in a heterogeneous mobile data network,” in IEEEGlobecom, New Orleans, LA, Nov 26-30, 2008.

[17] J.-H. Lee, S. Gundavelli, and T.-M. Chung, “A performance analysison route optimization for Proxy Mobile IPv6,” in IEEE InternationalConference on Communications, ICC 2009, Dresden, Germany, Jun 14-18, 2009.

[18] P. Chowdhury, M. Atiquzzaman, and W. Ivancic, “ SINEMO: An IP-diversity based approach for network mobility in space,” in Second IEEEInternational Conference on Space Mission Challenges for InformationTechnology (SMC-IT), Pasadena, CA, Jul 17-21, 2006.

[19] A. Z. M. Shahriar, M. S. Hossain, and M. Atiquzzaman, “A cost analysisframework for NEMO prefix delegation-based schemes,” Universityof Oklahoma, Technical report, TR-OU-TNRL-10-101, January 2010,http://cs.ou.edu/∼netlab/.

[20] M. S. Hossain, M. Atiquzzaman, and W. Ivancic, “ Cost analysis ofNEMO protocol entities,” in International Conference on Computer andInformation Technology, Dhaka, Bangladesh, Dec 23-25, 2010.

[21] M. S. Hossain and M. Atiquzzaman, “ Stochastic properties and applica-tion of city section mobility model,” in IEEE Global CommunicationsConference (GLOBECOM), Honolulu, HI, Nov 30- Dec 4, 2009.

[22] P. Chowdhury, A. Reaz, M. Atiquzzaman, and W. Ivancic, “ Performanceanalysis of SINEMO: Seamless IP-diversity based Network Mobility,”in IEEE ICC 2007, Glasgow, Scotland, Jun 24-28, 2007.

Md. Shohrab Hossain received his B.Sc. andM.Sc. in Computer Science and Engineering fromBangladesh University of Engineering and Tech-nology (BUET), Dhaka, Bangladesh in the year2003 and 2007, respectively. Currently he is a Re-search Assistant, and working towards his PhD inthe School of Computer Science at University ofOklahoma. His research interests include mobility ofIPv6 networks, mobility models, security, scalabilityand survivability of wireless and mobile networks.

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Page 14: Cost and Efficiency Analysis of NEMO Protocol Entities · Cost and Efficiency Analysis of NEMO Protocol Entities Md. Shohrab Hossain, Mohammed Atiquzzaman School of Computer Science,

Mohammed Atiquzzaman obtained his M.S. andPh.D. in Electrical Engineering and Electronics fromthe University of Manchester. He is currently a pro-fessor in the School of Computer Science at the Uni-versity of Oklahoma, and a senior member of IEEE.Dr. Atiquzzaman is the editor-in-chief of Journalof Networks and Computer Applications, co-editor-in-chief of Computer Communications journal andserves on the editorial boards of IEEE Communi-cations Magazine, International Journal on Wirelessand Optical Communications, Real Time Imaging

journal, Journal of Communication Systems, Communication Networks andDistributed Systems and Journal of Sensor Networks. Dr. Atiquzzaman hasreceived Edith Kinney Gaylord Presidential Professorship for meeting thehighest standards of excellence in scholarship and teaching at Universityof Oklahoma. In recognition of his contribution to NASA research, hereceived the NASA Group Achievement Award for ”outstanding work tofurther NASA Glenn Research Center’s effort in the area of AdvancedCommunications/Air Traffic Management’s Fiber Optic Signal Distributionfor Aeronautical Communications” project. He is the co-author of the book”Performance of TCP/IP over ATM networks” and has over 220 refereedpublications, available at www.cs.ou.edu/∼atiq. His research interests are inwireless and mobile networks, ad hoc networks, and satellite networks. Hisresearch has been funded by National Science Foundation (NSF), NationalAeronautics and Space Administration (NASA), U.S. Air Force, and Ciscothrough grants totaling over $3.8M.

William Ivancic has over twenty-five years expe-rience in network and system engineering for com-munication applications, communication networkingresearch, state-of-the-art digital, analog and RF hard-ware design and testing. He currently is a seniorresearch engineer at NASA’s Glenn Research Cen-ter where he directs the hybrid satellite/terrestrialnetworking, space-based Internet, and aeronauticalInternet research. He has lead research efforts todeploy commercial-off-the-shelf (COTS) technologyinto NASA missions including the International

Space Station and Shuttle. Mr. Ivancic is also performing joint research withCisco System on advance routing research for space-based and aeronautic-based networks. Of particular interest is large scale, secure deployment ofmobile networks including mobile-ip and mobile router technology. Recentaccomplishments include being first to demonstrate and deploy secure mobilenetworks in an operational government network, the US Coast Guard, first todeploy Mobile-IP Mobile networking on a space-based asset, the Cisco routerin Low Earth Orbit (CLEO, first to deploy Internet Protocol security (IPsec)and Internet Protocol version 6 on a space-base asset, and first to deploydelay/disruption network technology bundling protocol in space.

Mr. Ivancic is also the principal of Syzygy Engineering, a small consultingcompany specializing in communications systems and networking as well asadvanced technology risk assessment. Mr. Ivancic is currently performingresearch and development on Identity-based security and key and policymanagement and distribution for tactical networks - particularly mobilenetworks.

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