An Analysis of the Handover for Hierarchical MobileIPv6

Chan Lee YeeDepartment of Electrical, Electronics and Systems

EngineeringUniversiti Kebangsaan Malaysia

43600 UKM Bangi Selangor, MALAYSIAlychan_80gyahoo.com

Abstract- Mobility support for mobile networks becoming moreimportant as the mobile Internet becomes popular. The IETFMobile Internet Protocol version 6 (MIPv6) enablesCorrespondent Nodes (CNs) to send packets directly to a mobilenode (MN) using Care-of address of the mobile node. To reducethis control signaling, the existing hierarchical scheme built ontop of the MIPv6 separates micro-mobility from macro-mobilityand exploit mobile node's locally. This paper describes videostreaming QoS analysis on the HIMIPv6 testbed. Throughput forMN during handoff has been analyzed and the conclusion showsthat throughput is dropping during handover process.

Index Terms-Mobile IP, IPv6, handoff, performanceevaluation

1. INTRODUCTION

THE Mobile IP protocol (MIPv4, MIPv6) has beenproposed by the IETF as a basic protocol in order to

support terminal mobility in the Intemet[l]. Besides theiradvantages, it also has some limitations such as high latencyduring the handover process. Various studies have beencarried out to enhance MIP protocol so that the latency, packetloss and signaling overhead experienced during handoff can bereduced. HMIPv6 is proposed to separate mobility into micro-mobility (within one domain) and macro-mobility (betweendomains). Furthermore, HMIPv6 can also reduce the delay andthe amount of signaling during handover [21[3].

A. Mobile IPv6MIPv6 is a basic IP mobility management schemes that wasdesigned to allow nodes to be reachable and maintain ongoingconnection while changing their location within thetopology[4]. In MIPv6, a Mobile Node (MN) has two IPaddresses, a Home Address and a CoA. Home address is anaddress in the network that the mobile node belongs to, whileCoA is mobile node's temporary address in the visitednetwork. The home address is fixed but the CoA changes asthe MN moves. When a MN moves from its home network toforeign network, a new CoA will be assigned. Followingaddress configuration, the MN informs it HA and of suchmovement by sending a Binding Update (BU) message. Homeagent is a router in the home network that is used as a

Mahamod Ismail, Kasmiran JumariDepartment of Electrical, Electronics and Systems

EngineeringUniversiti Kebangsaan Malaysia

43600 UKM Bangi Selangor, MALAYSIA{mahamodgeng.ukm.my, kbjgpkrisc.cc.ukm.my}

redirection point. When a node (correspondent node) needs tocommunicate with mobile node, it sends packets to the mobilenode's home address. Home agent then intercepts the packetsand forwards them to the MN current CoA. At this point, themobile node may decide to use the route optimizationprocedure. Route optimization involves packet routingbetween MN and CN, using shortest possible path. The MNEaware when packets are routed through the home agent. Whenit receives tunneled packets addressed to its home address, theMN can decide whether it should attempt to optimize the routebetween itself and CN. If so, the MN informs the CN itscurrent location by sending a signaling message (BindingUpdate) that contains its current CoA. The CN can then sendthe packets directly to the MN. However, mobile IPv6 mayhave problem to support real-time or loss-sensitiveapplication. Whenever mobile node moves from one AccessRouter to another, it should registers (or binding update) itsnew CoA to its HA and HA that the distance from MN may belong. While registration, the mobile node lost the connectionto correspondent node and it may induces packet loss andlatency.

B. Hierarchical Mobile IPv6Hierarchical mobile IPv6 (HMIPv6) was proposed to reduce

the time required for the binding update process byintroducing a Mobility Anchor Point (MAP) which is locatedbetween MN and home agent[6][7]. The HMIPv6 networkarchitecture as shown in Figure 1 illustrates an example ofusing MAP in a visited network.When a MN moves into a new MAP domain, the MN will

discover the global address of the MAP. This address is storedin the Access Routers and communicated to the MAP viarouter advertisements. Mobile node needs to acquire aRegional Care-of Address (RCoA) and an On-link Care-ofAddress (LCoA)[8]. RCoA is an address on the MAP'ssubnet, it is auto-configured by the MN when receiving theMAP option and it does not change when the MN roamswithin the domain. Whereas LCoA is configured on a MN'sinterface based on the prefix advertised by its default router, itchanges as the MN moves within the domain. The RCoA

1-4244-0000-7/05/$20.00 ©2005 IEEE. 941

essentially replaces the home address as far as the MN'scommunication with the MAP concemed. The MAP knowsnothing about the MN's real home address. HMIPv6 wasdesigned to allow MN to move within a particular domainwithout having to update their HA and CN every time theymove. Instead, they send one binding update to MAP locatedin the visited network. Certainly, this would minimize thenumber of binding update send to the HA. A MAP isessentially a local HA located in the visited network. Itintercepts all the packets addressed to the MN it serves andtunnels them to the corresponding on-link CoA of the mobilenode. If the mobile node changes its current address within alocal MAP domain, it only needs to register the new on-linkaddress with the MAP since that the global CoA does notchange[9][10[I1 I].

Figure 1: HMIPv6 Architecture [5]

Figure 2: HMIPv6 Routing Scheme

Figure 2 show the HMIPv6 routing scheme and the descriptionfor each message exchange is as follows:I. when mobile node enter into a new MAP domain, mobilenode's IP layer will send "Set Handoff Request' request toLink Layer, the Link Layer will then reply "Link upNotification".

2. Mobile node needs to reset its CoAs, which are RCoA andLCoA. Mobile node sends Router Solicitation to requestaccess router reply Router Advertisement. RCoA and LCoAwill be generated after received Router Advertisement.During Autoconfiguration, mobile node will performedduplicate address detection (DAD) to make sure no nodeperformed same LCoA.

3. After generated RCoA, mobile node send local BindingUpdate (BU) to MAP, MAP received the BU and willperform DAD check. MN has to wait for the check.

4. MAP will reply Binding Acknowledgement to mobile node,to inform mobile node's binding is success or not.

5. After finish the registration, mobile node need to register toits home agent. During this time mobile node will send onebinding update to home agent.

11. HMIPv6 TESTBED AND ANALYSIS RESULT

A. HMIPv6 testbed

Figure 3: HMIPv6 Testbed

Our testbed environment consists of 6 computers and a

notebook with kernel patch, mon-hmipv6-0.3-mpl-0.9.4.diff.All of these computers run in Linux Redhat 8.0 with kernel2.4.19 as operating system. Figure 3 show the HMlPv6 testbedthat we have built. Overall, our testbed consist of a CN, HA,MAP, ARI and AR2. HA is a router that is located in homewith address 2001:328:2004::2:1. MAP, ARI and AR2 are

942

......;..... No Ie

r................ ._... 42. :1 t <.:- i: ~~~~~~~~~~~~~~~~~~~~~~~~~...........V,,;*,< .R

-~~~~~~~~~~~~~~.. .. . . . ,, , , ,, -S'C$- r..E,s^><-: n-I

:.-.,.:t ,Ste tj~~~~~:z;j-;;t _V .. _ ._ .. s _~~~~~i

routers that located in visited network. Correspondent node(CN) in our testbed is a PC that supports IPv6 address place inhome link. Server application for the real-time videostreaming application based on UDP packet is installed in thisPC.Testing, analysis and measuring of the QoS parameters

(video streaming application) experiments will be done in thispaper. We assume MN already in MAP domain, and we willstudy the MN's ping-pong type of movement[13], that is MNwill move from domain ARI to domain AR2 and finally MNwill move back from domain AR2 to ARI. The impact of eachhandover towards the QoS parameters will be analyzed.B. Analyze Test Result

Figure 4 shows the traffic pattern for MN while MN enteredinto domain ARI. After Duplicate Address Detection (DAD)process, where RCoA and LCoA are auto-generated by MN,the MN will send binding update to ARI. ARI then reply MNby sending binding acknowledgement. Label I in Figure 4represented binding update send by MN, whereas label 2represented binding acknowledgements send by AR].Neighbor solicitation which is sending by MN can representlabel 3. The purpose of neighbor solicitation is to verify thatan access router (ARI) is still reachable via a cached link-layer address.

Figure 5 shows the traffic pattern for MN when MN roamsfrom domain ARI to domain AR2. Label 1 in Figure 5 isRouter Advertisement, it is sending by ARI to MN before MNentered into domain AR2.

Figure 4: Traffic at Mobile Node enter domain ARI

Label 2 represented as router solicitation and it is sending byMN. Neighbor solicitation is sending by MN which can beshown in label 3. It means that MN need to determine whichneighbor (access router) is reachable via a cached link-layeraddress. Neighbor Advertisement which is sending by AR2 tomobile node can be shown by label 4 in Figure 5. The purpo.eof neighbor advertisement is to tell MN that AR2 is the besthop to connect. Router solicitation which is sending by MNcan be shown by label 5 in Figure 5. While interface for MN isready to communicate, MN will send router solicitation torequest router (AR2) to generate router advertisement to MNimmediately. Label 6 is router advertisement which is sendingby AR2 to reply MN's request.

Figure 5: Traffic at Mobile Node enter from ARI to AR2

943

7 ; 0 0; : i: f; 8re*da 0in0Hr-t -

8

-:.~~~~~~~~~~~j -l -..

-- -.

N4iL-0''" 4Ei' - ': ' '- -S - - '- 0

-., '. ,:: S ,';I ^'. .' ' '- '. . 't

O. :- -.:: :- : - - ::: },: .:'i . .s .: .f .1i.I...- .... .fDt. ................

tv5 1 V | ' " ! '' 0 |'ec

Hoist Breakdown.0.004 -fe8022O2~~~~~~~~~~~~~~~~~~~~~~~~~~~~2dff-tfeA4372

6;--: :- -- -00L328:2004:12202:fr45-4

3 i- :020 2 12f4-5Q13fl3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~2001:-328:2004 .:2:1

0.~~~~~~~ff2:1 :ffb7±1c5.fe U0202-2 ff.,a:d7

0.0

20.--g;..-.---:: -0 220.- 0 .: -:-240 260 280

D''.'''D'j' "-:.' ',' - ' :\ -'\ ' - -;'/:':C-:: -Tim (sec)-- -::-0

Inside packet router advertisement included prefix of AR2which is for on-link determination and address configuration.After sending router advertisement and router solicitation, MNwill start to process Duplicate Address Detection (DAD). MNwith layer 2 MAC address "0:002:2D: B7: BC: 45" have tocheck whether a potential address,"2001: 328: 2004: 12 :202: 2dff : feb7 :bc45" is alreadybeing used by another node or not. After receivingadvertisement as above, MN will check the duplicate addressby sending "ff02: : 1: ffb7 :bc45 ', this is to make sure no

other nodes configure the same address. MN will thenconfigure itself with the global address"2001:328:2004:12:202:2dff: feb7:bc45"'. After thenew LCoA address was generated, MN then send bindingupdate to MAP through AR2. Finally, MAP will send bindingacknowledgement to MN. Both binding update and bindingacknowledgement signal can be shown by label 7 and 8 inFigure 5.The results presented show only the traffic pattems for MN

during handover occur. It proves that MN obtained new LCoAonce it entered into a new domain. Later, testing, analysis andmeasuring of the QoS parameters (video streamingapplication) experiments will be done. The impact of eachhandover towards the QoS parameters will be analyzed. Wewill capture the UDP packet from the real-time videostreaming application in MN. Here, we chose Videolan as our

analysis tools. Videolan software is chosen because it is UDPbased, and we believe that UDP based implementations will bethe mainstream of future networking multimedia applications,although the combined use of UDP and TCP could becomeuseful in adaptive networking multimedia models. Thus, it isimportant for us to understand the performance of UDP baseddata transmission in WLAN environment.

0q6-Q.0

i. :,'

..

Figure 6 show the throughput performance for mobile nodewhile MN receiving video stream packet when it roams fromdomain ARI to domain AR2. Handover occur at the time 175seconds. Before handover occur, total video stream packetssend to mobile node are constant, that is around 0.9 Mbps.When mobile node roams into domain AR2, handover occur

and the throughput drop to 0.25 Mbps. After process

handover, throughput increase to normal rate, that is 0.9 Mbps.Throughput drop is cause by the registration time. If there wasno latency in this process, the throughput should be constant at0.9Mbps. The latency of this period was measured to beapproximated 0.44 second. According to [14], where the meanvalue for the QoS-sensitive traffic is around 0.8 second, thiscan prove that the handover latency result is acceptable.

III. CONCLUSIONHierarchical Mobile IPv6 is one of the aspects which

proposed by IETF to improve the handover performance as

micro-mobility support in Mobile IPv6. This paper presentedhow MN generated a new LCoA during handover. The resultsshow that traffic pattern for MN while we apply multimediasoftware (Videolan software) on the HMIPv6 testbed.Throughput for MN has been analyzed during handover,which is from 0.9 Mbps to 0.25 Mbps. Handoff latency isapproximated 0.44 second where the result is accepted basedon [14].

Host Breakdown

:---200SOL 32BO4'ti2022dffieb7± -

---:20 2-.3dffi 2£:feTb :C c

02,

m:16 0:..14n

944

180

Figure 6: Throughput performance for MN while receiving video stream packet

d

.Ut

REFERENCES

[1] H. Soliman and K. El-Malki, "Hierarchical MIPv6 mobility management(HMIPv6)," Intemet Draft, IETF, June, 2003. Work in progress.

[2] Robert Hsieh, Aruna Seneviratne, Hesham Soliman, Karim El-Malki,"Performance analysis on Hierarchical Mobile IPv6 with Fast-handoffover End-to-End TCP," GLOBECOM 2002 - IEEE GlobalTelecommunication Conference, vol. 21, no. 1, November 2002, pp.2500 -2504.

[3] Koji OMAE, Masahiro INOUE, Ichiro OKAJIMA, and NarumiUMEDA, "Handoff Performance of Mobile Host and Mobile RouterEmploying HMIP Extension," WCNC 2004 - IEEE WirelessCommunications and Networking Conference, vol. 5, no. 1, March 2004,p.p. 2368-2373.

[4] Xavier P erez-Costal and Marc Torrent-Moreno, "A Performance Studyof Hierarchical Mobile IPv6 from a System Perspective," ACMSIGMOBILE Mobile Computing and Communications Review, Volume7, Issue 4, October 2003, p.p. 5-19.

[51 Hesham Soliman, Claude Castelluccia, Karim El-Malki, LudovicBellier, "draf-ietf-mobileip-hmipv6-03http:Ilwww. ietf/proceedings/l I marfslides/mobileip-2/sIdOO04. htn.

[61 Seung-Hee Hwang, Bo-Kyung Lee*, Youn-Hee Han", and Chong-SunHwang, "An Adaptive Hierarchical Mobile lPv6 with RouteOptimization", Vehicular Technology Conference, 2003. VTC-Spring.The S74 IEEE Semiannual, Volume 3, 22-25 April 2003, p.p. 1502 -1506.

[7] Hideaki Takahashi, Ryoichi Kobayashi, Ichiro Okajima, and NammiUmeda, "Transmission Quality Evaluation of Hierarchical Mobile IPv6with Buffering Using Test Bed", Vehicular Technology Conference,2003. VTC 2003-Spring. The 57th IEEE Semiannual," Volume4, 22-25 April 2003, p.p. 2246-2250.

[81 Axel Neumann, Xiaoming Fu, Holger Karl, "Prototype Implementationand Perfor-mance Evaluation of a QoS-Conditionalized Handoff Schemefor Mobile IPv6 Networks* ", in proc. IEEE Computer CommunicationsWorkshop (CCW), Laguna Nigu el, California, USA, October 2003.

[9] SangHeon Pack and Yanghee Choi, "Performance Analysis ofHierarchical Mobile 1Pv6 in IP-Based Cellular Networks:, in proc. IEEEConf Beqing, Sept. 2003

[10] Masaki Bandai and Iwao Sassase, "A Load Balancing MobilityManagement for Multilevel Hierarchical Mobile IPv6 Networks", IEEEInternational Symposium on Personal, Indoor and MobileCommtnications (PIMRC'03), pp.460-464, Sep. 2003.

[11] Koji OMAE, Ichiro, OKAJIMA, and Narumi UMEDA, "MobilityAnchor Point Discovery Protocol for Hierarchical Mobile IPv6,WCNC 2004 - IEEE Wreless Communications and NetworkingConference, vol. 5, no. 1, March 2004 pp. 2368-2373.

[121 Koji Omae, Masahiro lnoue, Ichiro Okajima, Narumi Umeda,"Handoff performance of mobile host and mobile router employingHMIP extension", WCNC 2003 - IEEE Wireless Communicationsand Networking Conference, vol. 4, no. 1, Mar 2003 pp. 1218-1223.

[131 Zongkai Yang, Yuming Wang, Dasheng Zhao, Jianhua He,Xiaming Fu, "Fast Seamless Handover Scheme and CostPerformance Optimization for Ping-Pong Type of Movement",16th IEEE Int'l Symp. On Personal Indoor and Mobile RadioCommunication (PIMRC), Berlin, Gernany, Sept 2005.

[141 Steffen Sroka, Holger Karl, 'Performance Evaluation of a QoS-Aware Handover Mechanism", Telecommunication NetworksGroup, Technische UniversifStBerlin.

945