An MPLS/HMIPv6 Based Mobility Management ...

An MPLS/HMIPv6 Based Mobility Management Framework for GPRS/WLAN Integration Architecture Iti Saha Misra

Chandi Pani (Banerjee)

Electronics and Telecommunication Engineering Dept. Jadavpur University, Kolkata-700032, India email:[email protected],

Electronics and Communication Engineering Department Meghnad Saha Institute of Technology, Kolkata-700150, email:[email protected]

Abstract— During last couple of years, cellular system becomes one of the popular wirelesses Communication mediums. But in the hot spot region use of WLAN is increased due to its high data rate and low installation cost. So there is a requirement for suitable integration technique of 3G/GPRS and WLAN to increase the area of coverage and high data rate. In this paper, we present an integration of GPRS and WLAN in connection with Multi protocol label switching (MPLS). The mobility is managed by hierarchical mobile IPv6 (HMIPv6). The aim of this paper is to design seamless mobility with low signaling overhead and provision for optimal quality of service (QoS). Performance analysis of the integrated framework is done for signaling overhead. Simulation result based on ns-2.26 indicates better throughput and faster switching. Thus ensure optimal QoS for the integrated framework. Keywords- GPRS, WLAN, MPLS, fast handoff

I.

INTRODUCTION

In the recent time, there is a trend to provide high speed data access and sophisticated service based on IP, that motivate the mobile operator to transit towards 3G starting from 1G. WLAN [1] provides high data rate with low cost but one of the major drawbacks of this is limited area of coverage. Cellular systems [1] are one of the popular wireless access technologies in communication domain. It has moved through different generations like 1G, 2G (GSM, DAMPS), 2.5G (GPRS, EDGE) followed by 3G (UMTS). In 1992, International Telecommunication Union (ITU) has issued International Mobile Telecommunication for year 2000 (IMT-2000) which defines the basic characteristics of 3G. But due to the high deployment cost, 3G is not globally accepted into the market. Advantages of cellular system are: wide coverage, well known voice service whereas limitations are: low data rate and more costly compared with WLAN. A. Focus of Integration Considering the advantages and disadvantages of WLAN and Cellular systems, our focus of integration is to develop a network comprising the best features of these two heterogeneous technologies. Our integration model will allow GPRS users to access the WLAN services from hotspot regions whenever they require high data rate and switch back in GPRS

This work is supported by CMCC, UGC project under University with Potential for Excellence at Jadavpur University, Kolkata, India

1-4244-0340-5/06/$20.00 ©2006 IEEE

region when the service quality of the WLAN is not satisfactory or they are outside the WLAN region. B.

Related work There are different proposals regarding integration of these two technologies. Tight Coupling integration architecture (TCIA) is proposed in [2]. But it has several disadvantages: TCIA injects the WLAN traffic directly towards the core network thus increases the overall traffic in the core network. Secondly, the core network is completely exposed to WLAN network which violets the security and privacy of cellular networks. Integration based on loose coupling (LCIA) [3] is introduced to overcome the disadvantage of TCIA. LCIA use mobile IP (MIP) [4] to provide seamless mobility. MIP provides mobility by hiding the change of IP address, when mobile node roams between different networks. But this scheme has some disadvantage of triangular routing and seamless mobility in hand off intensive environment. So, MIP introduces significant network overhead in terms of increased delay, packet loss and signaling when the user changes its point of attachment very quickly. To overcome these deficiencies hierarchical mobile IP (HMIP) based protocols [5] have been proposed that worked on a model, which divides the network into domain and domains are further subdivided into subnets. HMIPv6 [5] is based on MIPv6 platform that introduces a new entity called mobility anchor point (MAP), the major idea is that once mobile node (MN) registers with MAP’s CoA with home agent (HA), there is no requirement of further registration when MN moves locally i.e within the scope of MAP. So this method provides low signaling overhead and less number of location update. Multi protocol label switching (MPLS) [6] is a labelforwarding scheme provides a good solution for faster switching. When it is used in conjunction with IP, conventional IP look up and forwarding within the network is replaced by faster label look up and switching, the IP header is analyzed only in entry and exit point of the networks. There are so many advantages of MPLS systems [7], which motivate us to use MPLS in mobile wireless architecture. This method also provides better QoS, traffic engineering, fast hand off and support advanced IP based service like virtual private networks. Related works that introduce mobility in MPLS domain is mainly based on MIPv4 and HMIPv4 [8]. [9]

Integrates the protocols HMIPv6 and M-RSVP over M-MPLS in order to provide QoS in IP network mobility. [10] Integrates 3G/GPRS/WLAN based on TLMM protocol where a global mobility agent is placed at the integration point to handle inter domain mobility.

CN HA

II. PROPOSED MPLS/HMIPV6 BASED INTEGRATION GPRS/WLAN FRAMEWORK Fig.1 shows the MPLS/HMIPv6 based integration GPRS/WLAN framework where two heterogeneous networks GPRS and WLAN are considered as two different domains. In our proposed architecture, to increase the scalability of GPRS and WLAN, two separate MPLS domains are formed between Gateway GPRS support node (GGSN) to Serving GPRS support node (SGSN) and WLAN gateway router (WGWR) to Access router (AR) respectively. So GGSN, SGSN, WGWR and AR all act LEMA for their corresponding domains. For GPRS domain GGSNLEMA acts as ingress and SGSNLEMA acts as egress label edge router (LER) and for WLAN domain WGWRLEMA is the ingress and AR is the egress LER. To get the advantage of reduced signaling overhead the mobility of our integrated framework is handled by HMIPv6. All the LEMAs are considered as IPv6 enabled AR and they are placed at different hierarchical level of the integrated framework. According to HMIPv6, MAP can be placed at any level of AR. If it is placed just above AR, then GGSNLEMA and WGWRLEMA both will act as MAP for the corresponding domains. In this situation, when MN moves from GPRS to WLAN and vice versa, it is required to inform home agent (HA) for location update and will increase signaling in core network. To eliminate this extra overloading and signaling, we place MAP at the integration point of the two heterogeneous networks. Again from the scalability and

FA Network 2

MAP LEMA

C. Motivation Next Generation (NG) wireless networks offer the promise of integrating high-speed access network with the IP based services to the mobile users. MPLS is also proposed as a transport option in the access networks of NG wireless networks [11]. Considering the bests of existing protocols, in this paper, we introduce HMIPv6/MPLS based GPRS /WLAN integrated framework for seamless mobility. Our framework uses the enhanced type of MPLS router called label edge mobility agent (LEMA) that are placed at different hierarchical level of the integration framework. LEMA takes an active part in mobility management. To control the intra network mobility MAP is placed at the integration point of the network. So our proposed framework would satisfy the seamless mobility with fast packet forwarding, fast hand off, minimum packet loss during hand off, minimum delay and reduced location update that make our framework more scalable and can handle micromobility as well as global mobility efficiently. Our objective is to reduce signaling cost with seamless mobility at the same time providing provision for better traffic management for required QoS in the cellular-WLAN integration model. Though we consider GPRS network, this framework is valid for 3G/WLAN integration also.

INTERNET

R1 MAP Network domain

R2

R3

WGWR LEMA

R4

GGSN LEMA R5 R6

R8

SGSN1 LEMA/ AR1

BSC1

R9 R7

SGSN2 LEMA/ AR2

BSC2

GPRS domain

R10

R11

AR3 LEMA

AR4 LEMA

BSC3

WLAN domain

MN

HA-home agent, CN- correspondent node, MAP LEMA-MPLS enabled MAP, GGSNLEMA-MPLS enabled GPRS gateway LEMA, WGWRLEMA-MPLS enabled WLAN gateway LEMA, SGNNLEMA-MPLS enabled serving GPRS support LEMA, MN-mobile node, ARLEMA-MPLS enabled Access router, BSC- base station controller MPLS Router

Access point.

Figure 1 Proposed integrated framework

fast packet forwarding aspect another MPLS domain is formed between MAP and two heterogeneous networks where MAP is the ingress and GGSNLEMA and WGWRLEMA are the egress LER. During registration, all the LEMAs are modified their label forwarding information base (LFIB) by placing the care of address (CoA) of MN in the forward equivalent class (FEC), also modify their label forwarding table (LFT) by placing the in-label and out-label value for next hop information and a new label switch path (LSP) is established afterward. During packet forwarding, ingress LER encapsulates the packet, pushes a label value in front of IP header and forwards it to next label switch router (LSR) in MPLS domain. In LSR, no header analysis is performed; only by 20-bits label swapping packet is forwarded to next hop. At the egress LER,

MPLS label is popped out and packet is forwarded to its destination. In our proposed architecture user equipment (UE) must have dual mode terminal to interface GPRS and 802.11b.The 802.11b interface allow the user to operate in WLAN domain and GPRS driver allow the user to operate in GPRS domain. The initial registration request bit format based on HMIPv6 of MPLS based integrated framework is shown in Fig. 2 0 31 Header Length L

K

I

15 MH Type Checksum R G Reserved 128 bit Source address

LI

B. Inter domain mobility MN moves from GPRS to WLAN domain that means from BSC3 to AR3. Here MAPLEMA takes the full responsibility about the movement of MN. So registration is required up to this level, no requirement to inform HA. Table III, IV and V shows modified LFIB for MAPLEMA, WGWRLEMA and AR3. TABLE III. IL -

IF -

Sequence Life Time

FEC WGWR

TABLE IV. IL 11

128 bit Destination address

IF i-o

Exp

FEC AR3 TABLE V.

128 bit CoA address label 0 31

OL 11

S

IL 21 -

TTL 19

IF i-o -

FEC AP MN

LFIB FOR MAPLEMA OF i-o

S 1

T T

Note MAP-WGWR

LFIB FOR WGWRLEMA OL 21

OF i-o

S 1

T T

Note WGWR-AR4

LFIB FOR AR3LEMA OL -

OF -

S 1 -

T T T

Note AR3-AP AP-MN

Figure.2 Registration request message format based on MPLS/HMIPv6

III.

MOBILITY MANAGEMENT FOR INTEGRATED FRAMEWORK

The mobility management of integrated framework can be classified into three categories: Intra domain mobility: movement of MN under similar domain that means either within GPRS or WLAN domain. Inter domain mobility: movement of MN from one domain to another i.e from GPRS to WLAN. Global mobility: movement of MN from one network to another. It needs global update. Finally, complete content and organizational editing before formatting. Please take note of the following items when proofreading spelling and grammar: A. Intra domain mobility Here we consider the mobility within the GPRS domain i.e from one SGSNLEMA to another. GGSNLEMA takes the full charge to control the mobility within this domain; there is no requirement to inform MAPLEMA about handoff. According to our framework MN moves from BSC2 to BSC3. Table I and Table II show the modified LFIB for SGSN2LEMA and GGSNLEMA. We consider S as segmented flag; T as the active time for which MN belongs to a domain. TABLE I. IL

IF

FEC

1

i-o

SGSN2

MODIFIED LFIB FOR GGSNLEMA OL

OF

S

T

3

i-o

1

T

IF i-o -

FEC BSC3 MN

GGSN-SGSN2

LFIB FOR SGSN2LEM

TABLE II. IL 3 -

Note

OL -

OF -

S 1 -

T T T

Note SGSN2-BSC3 BSC3-MN

C. Global mobility In this case MN moves to a new network that mean under different gateway router. According to Fig.1 MN enters a new network network2 where foreign agent (FA) acts as gateway router. From the agent advertisement MN finds that base station BS is the serving base station under that FA. As MN enters a new domain new registration is required up to HA so the location update is required only in this level. IV.

PERFORMANCE ANALYSIS

In this section we present the performance analysis of integrated framework in respect of handoff and signaling overhead. A.

Handoff

When a labeled packet enters into MPLS domain, only the edge router process the entire header, but in the intermediate routers only 20 bits label is processed. The time required to process 20 bits is less as compared to process whole header bit. For MPLS domain, with the increase of number of router the processing time is not increased in large extent as in the intermediate router no header encapsulation is performed. Handoff delay requires configuring new CoA and LSP set up time. Hand off time depends how fast the switching is done during the movement. In case 1, for intra domain mobility we see that BSC2 and BSC3 are under same GGSNLEMA, so there is no requirement to inform HA about MN’s movement. Registration is required up to GGSNLEMA and LFIBs modification is required as given in Table I and Table II. Afterward, a new LSP is set up between GGSNLEMA to SGSN2LEMA. In case 2 for inter domain mobility when MN moves from GPRS to WLAN domain, as they are under same MAPLEMA intra domain registration is required up to this level. MAPLEMA modifies its LFIB and make a new LSP from MAPLEMA to WGWRLEMA. In case 3 for global movement, MN enters a new network so global registration up

Calculation of signaling overhead:

During packet forwarding in MPLS domain only 20 bit label value is processed by the router, irrespective of full IP header analysis. Thus signaling overhead is reduced drastically. The following calculations will show the results. Let, L=64: size of registration packet in bytes, (According toFig.3) NSGSN=6: number of hops NGGSN=8: number of hops NGWR=10: number of hops NHA=12: number of hops from arbitrarily chosen).

from MN to SGSNLEMA from MN to GGSNLEMA from MN to GWRLEMA MN to HA (These values are

MN to SGSN 3G/WLAN MN to GGSN 3G/WLAN MN to GWR 3G/WLAN

2000

1500

MN to SGSN 3G/WLAN/MPLS MN to GGSN 3G/WLAN/MPLS MN to GWR 3G/WLAN/MPLS

1000

500

0 0

Ts = average time for which MN belongs to under same SGSNLEMA (sec) Td = average time for which MN belongs to domain (sec) Tg = average time for which MN belongs to same MAPLEMA (sec) N= number of SGSNLEMA under same GGSNLEMA M= number of GGSNLEMA under same GWRLEMA Therefore, Td = N*Ts and Tg = M*Td The signaling overhead of edge router is 2* L/Ts and in the intermediate router signaling overhead is 2* (N-1)*(20/8)*Ts because in the intermediate router no header analysis is performed only 20 bit label is changed. Therefore the total signaling overhead under subnet is 2*L/Ts[1+( N-1)20/(8*L)], Where N is the number of routers. Table VI shows the comparative chart for signaling overhead of integrated architecture and Table VII shows the total signaling overhead of integrated architecture. TABLE VI.

Signaling overhead of integrated framework

2500

COMPARATIVE CHART FOR SIGNALING OVERHEAD Up to SGSNLEMA

Up to GGSNLEMA

Up to MAPLEMA

GPRS/WLAN

2*NGGSN*L/Td

2*NGWR*L/Td

2*NHA*L/Tg

GPRS/WLAN /MPLS

2*L/Ts[1+(NGGSN1)20/8L]

2*L/Td[1+(NGWR1)20/8L]

2*L/Tg[1+(NHA1)20/8L]

1

2

3

4

5

6

Subnet change period (sec)

Fig.3 Relation between signaling overhead at different level of integrated framework with subnet change period Signaling overhead (bytes/sec)

B.

signaling overhead in case of MPLS based integrated framework. Signaling overhead (bytes/sec)

to HA is now required. So the number of global location update is less in our proposed framework.

Total signaling overhead of integrated framework 4500 4000 3500 3000 2500 2000 1500 1000 500 0

3G/GPRS/WLAN 3G/GPRS/WLAN/MPLS

0

1

2

3

4

5

6

Subnet change period (sec) Fig.4 Relation between total signaling overheads of integrated framework with subnet change period

V.

NETWORK EVALUATION AND SIMULATION

We have performed a series of simulations in order to evaluate the GPRS/WLAN/MPLS based hierarchical architecture in multi domain scenarios. The simulations are implemented using Network Simulator 2.26 [12] (ns-2.26). Fig.5 shows the network topology used for simulation purpose. The entry point of the network is MAP which is an IPv6 router and GGSN, SGSN, WGWR, AR forms an integrated GPRS/WLAN MA

TABLE VII.

GPRS/WLAN GPRS/WLAN/ MPLS

COMPARATIVE CHART FOR TOTAL SIGNALING OVERHEAD

R3

Total signaling overhead 2*NGGSN*L/Td+2*NGWR*L/Td+2*NHA*L/Tg 2*L/Ts[1+(NGGSN-1)20/8L] +2*L/Td[1+ (NGWR-1)20/8L]+2*L/Tg[1+(NHA-1)20/8L]

R4

GGSN R5

R6

R7 SGSN1

Fig.3 is the plot for signaling overhead at different level of integrated framework with subnet change period and Fig.4 is that of total signaling overhead of integrated framework. From Fig.4 we see that there is an improvement of 85% in total

R1

R2

R8 SGSN

WGWR R9 R11 AR1

R10 R12 AR2

Figure 5 Network topology used for simulation

From Fig.6 it is seen, for both cases bandwidth consumption is same, but MPLS based framework takes less time to forward packet in its destination. For large network this effect will be more prominent. So GPRS/WLAN/MPLS based framework provides faster switching and thus scalable. Fig. 7 depicts packet loss scenarios for integrated framework. Fig.8 shows the bandwidth consumed by the network when an UDP packet of 800kbps is sent from MAP to SGSN in the MPLS based integrated framework. It is simply an example to show the performance improvement for QoS provision using explicit route traffic engineering scheme for integrated framework. It is observed that by the application of traffic engineering network consumed less bandwidth, which in turn improves the network throughput. Consumed bandwidth (Mbps)

0.07 0.06 0.05 0.04 0.03 0.02 0.01 0

MPLS IP

0

10

20

30

40

Time (sec)

Figure 6 Delay for each flow for first exponential traffic Packet loss in integrated framework 2.5

3G/GPRS/WLAN 3G/GPRS/WLAN/MPLS

No. of packet

2 1.5 1 0.5 0 0

10

20

30

40

50

Time (sec)

Figure 7 Packet losses in the integrated framework

60

0.5 0.4 0.3 0.2

Without TE

0.1

With TE

0 0

2

4

6

Time (sec) Figure.8 Bandwidth consumed by the network

VI.

CONCLUSION

In this paper, we have proposed an MPLS/HMIPv6 framework on GPRS/WLAN integrated network to manage intra, inter and global mobility in seamless manner. This scheme supports faster hand off and reduces global location updates by placing MAP to restrict inter domain handoff and to support scalability. During frequent movement from GPRS to WLAN and vice versa, faster switching reduces packet loss and forward packets faster from MAPLEMA to MN compared to GPRS/WLAN integrated framework. Improvement of total signaling overhead for MPLS based framework is achieved. Preliminary simulation results ensure our proposed integration model for reduced packet loss, provision for QoS by the application of traffic engineering. REFERENCES [1]

Consumed bandwidth vs. time

Bandwidth consumed by the network

0.6

Bandwidth (Mbps)

framework. In this case all the intermediate routers are the IP routers. But when we integrate this network with MPLS all the edge routers (i.e MAP, GGSN, SGSN, WGWR, AR) are IP/MPLS router and all the intermediate routers are replaced by LSR. In simulation scenario, we consider all the links have the capacity of 1Mb with 100ms delay. We consider that MN is under SGSN1 and MAP is source node sends different types of packets for simulation. We use distance vector algorithm for route selection and three exponential traffic of property packet size 200, burst 2 sec, idle 1 sec and rate 100k, 200k, 300k respectively flowing from MAP to SGSN for 60 sec. Out of these three traffics, first traffic flows from 10 sec to 30 sec. Fig.8 shows the delay for each flow for first exponential traffic. Fig.10 shows the packet loss in the integrated framework during the run time of three exponential packets.

Jeffrey Bannister, Paul Mather and Stebastian Coope, Convergence Technologies for 3G Networks – IP, UMTS, EGPRS and ATM, John Wiley and Sons, Ltd, 2004. [2] Muhammed Jassemuddin," Architecture for Integrating UMTS & 802.11 WLAN Network", IEEE Symposium on Computer Communications ISCC, Turkey, 2003, pp.1-8. [3] Milind M. Buddhikot, Girish Chandranmenon, Seungjae Han, Yui-Wah Lee, Scott.Miller, Luca Salgarellie, " Design and Implementation of a WLAN/CDMA 2000 Internetworking Architecture", IEEE communication Magazine, November 2003, pp.93-97. [4] C. Perkins, Ed., " IP mobility support", IETF RFC 2002, Oct, 1996. [5] H. Soliman, C. Castelluccia, K. El Malki and L. Bellier, “ Hierarchical MIPv6 Mobility Management”, draft-soliman-mobileip-hmipv6-05.txt , IETF, July 2001, Work in Progress. [6] S. Jha and M. Hassan, Engineering Internet QoS, Artech House, 2002. [7] Fabino M. Chiussi, Denis A.Khotimsky, Santosh Krishnan, Lucent Technologies, "Mobility Management in 3G All IP Networks", IEEE Communication Magazine, September, 2002. [8] Kaiduan Xie, Victor C.M Leung, "A MPLS Framework for Macro and Micro Mobility Management". pp. 549555,Orlando,FL,USA,March2002. [9] Jesus Hamilton Ortiz, "Integration of Protocols HMIPv6 and M-RSVP over M-MPLS in order to Provide QoS in IP Network Mobility", University Polytechnic of Madrid, Spain, ETSI Telecommunication. [10] Iti Saha Misra, Sudipta Dey and Debashis Saha ," 4G All IP Integration Architecture for Next Generation Wireless Internet", ICWN 2005, Las Vegas, USA. [11] R. Langur, G. Le Grand, S. Tohme, “Micro Mobile MPLS Protocol in Next Generation Wireless Access Networks”, MASCOTS, Netherland, Oct 2004. [12] ns-2 home page, http://isi.edu/nsman/ns.