Location Management Agent for SCTP Handover in Mobile Network

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1 Location Management Agent for SCTP Handover in Mobile Network Yong-Jin Lee Department of Technology Education, Korea National University of Education 250 Taesungtapyon-ro, Heungduk-ku, Cheongju, South Korea Abstract This paper aims to describe and discuss about the location agent to support the SCTP (stream control transmission protocol) handover in mobile network. Related literatures about typical mobility and location schemes are presented. Features of TCP and SCTP over MIP (mobile IP) and SCTP over IP are also described respectively. Mobility requires the address reconfiguration during handover. This address update can be performed either by (mobile node) or (correspondent node) during handover, and can increase the handover latency. This paper proposes the LMA (location agent) that can reduce the handover latency by performing the address reconfiguration instead of and. This agent is especially efficient in the s ping pong behavior environment. Keywords: handover, SCTP, location agent INTRODUCTION Location is one of important research issues in the recent mobile network [1-9]. During the SCTP handover, the IP address of (mobile node) is changed, so the fact should be informed to the (correspondent node) communicating with the promptly. should reconfigure the address of in order to continue the seamless communication. In the location, this address reconfiguration is mainly performed by interchanging the binding update between and, which increases the handover latency remarkably. Although the SCTP handover schemes with the IP address reconfiguration [10-15] provides or with the binding update, it does not support the fast agent scheme proposed in this paper. We focus on the IP address reconfiguration during SCTP handover when MIP (mobile IP) is used or not in the lower layer. The proposed agent scheme can be applied to the mobile network design by using the SCTP over IP and MIP. We first describe typical mobility schemes including TCP and SCTP over MIPv4/MIPv6 and then propose the location agent for SCTP handover. We also discuss about the application procedure of the proposed agent to the SCTP with/without MIP. In order to implement our scheme, we extend the packet format of the SCTP with add_ip reconfiguration. The rest of the paper is organized as follows. In section 2, we describe several handover schemes including SCTP over MIPv4 and MIPv6, respectively. Section 3 discusses the location agent in SCTP handover scheme, followed by concluding remarks in section 4. MOBILITY AND LOCATION MANAGEMENT SCHEMES In the original MIPv4 [3], handover procedure is as follows: Firstly, HA (home agent) and FA (foreign agent) informs itself by using agent advertisement message similar to ICMP (internet control message protocol) router discovery. also can advertise by using agent solicitation message. can decide if it is in the home network through such an advertisement message. Secondly, exchanges the registration request message and the registration reply message with the HA. It registers the CoA in the HA. There are two types of CoA s: CoA of FA is used for (CoA). Temporary IP address by DHCP (dynamic host configuration protocol) is used for (Colocated CoA). Such a registration message uses UDP port 434 and contains CoA and lifetime of. After successful registration between HA and is performed, datagram sent from to the home address of is tunneled to the CoA of. Datagram from to has not been tunneled. It is forwarded to the destination by using the standard IP routing. In the MIPv4 with route optimization options, we can eliminate the triangular routing problem where HA becomes the bottleneck point as the number of increases. In the route optimization, manages the binding cache. Instead of sending datagram to HA, sends datagram to directly using tunneling. When the moves, this method provides with the forwarding datagram sent to the previous FA and datagram sent by old cache binding to the current position. Although mobile IP provides a simple and scalable mobility scheme, it is not appropriate for high mobility and seamless handovers. In fact, it envisages that every time a node migrates, a local address must be obtained and communicated to a distant local directory, called HA. This updating procedure, together with route optimization, introduces delays and data transfer disruption while the obtains the new binding. Moreover, as the number of mobile hosts increases, the traffic load generated by the update messages can have a drastic effect on the Internet and on the HA as well. Cellular IP defines a wireless access network architecture and protocol for managing micro-mobility. The cellular IP node embeds different functions, such as wireless access point, IP packet routing and cellular control functionality. The nodes implement cellular IP integrated routing and location 7532

2 and are built on regular IP forwarding engine. A gateway connects the cellular IP network to the Internet. Table 1 summarizes the location and binding updates, features (advantage and disadvantage), and who performs the location when TCP and SCTP over MIPv4 and MIPv6 [6,7,8,9] are used respectively. In the table, we find out that the binding update is performed at the IP layer and IP address reconfiguration is performed at the SCTP layer (_add_ip), respectively. Table 1: TCP and SCTP over MIP Location Features Who performs (advantage/ the location and binding disadvantage)? updates TCP over packet loss, IP layer only MIPv4/v6 large handover latency SCTP over Location HA, FA for each IP layer MIPv4 subnet (binding and binding,ha,fa update) and update Data must have MIP- SCTP layer tunneling (triangular duplicate registration (_ add_ip) problem) HA bottleneck SCTP over Location HA, FA for each MIPv4 with subnet, HA, route and binding FA, must optimization update have MIP Binding cache duplicate in only registration with INIT tunneling during handover in L3 and L4 layer SCTP over intrinsic route HA and MIPv6 optimization must have MIP only INIT duplicate tunneling registration with during handover in L3 and L4 layer Table 2 represents the location and binding updates, features (advantage and disadvantage), and who performs the location when SCTP over IP is used. The location is provided by SCTP over IP (v4 or v6) with the location agent. That is, SCTP only performs the location. Table 2: SCTP over IP Location Features Who performs (advantage/ the location and binding disadvantage)? updates SCTP over No location IP(v4 or v6) (only from to ) SCTP over Location need not MIP on SCTP layer IP(v4 or v6), need not (register and with the and update HA, FA per _ location with only subnet need the add_ip) INIT location agent tunneling agent which covers the several subnets SCTP performs the location LOCATION MANAGEMENT AGENT FOR SCTP HANDOVER Who performs the registration update There are two methods that perform registration updates in the SCTP handover. One of them is for to update the registration. TABLE 3 describes the update time, features, and requirements when performs the registration update. Table 3: registration update Description Features Requirement Initialization: Advantage: the 1) need to registration SCTP of additional packet define the update registers the home is not necessary registration address to the Disadvantage: message location since the SCTP of and reply registers the format. agent new IP address 2) may use During handover: during the the UDP when SCTP of handover, the total protocol obtains the time might like MIP new IP in the become too 3) need to overlapped longer. install the region, it registers LMA on on the location the routeror host agent Figure 1 shows the registration timeline. In the Figure 1, Location Mgt Broker represents LMA (location agent). 7533

3 Location Mgt Broker Old AR Location Mgt Broker Old AR New AR SCTP (add_ip) -ACK Router Advertisement Registration New IP configuration Simultaneously send add_ip Initialization Handoff Simultaneously send Register Request New AR SCTP (add_ip) -ACK Router Advertisement Registration New IP configuration add_ip Initialization Handoff Figure 2: registration timeline Figure 1: registration timeline registration Table 4 describes the update time, features, and requirements when performs the registration update. Disadvantage of this method is to require the modification of the for to be able to know the IP of LMA and to inform the registration completion to the (LMA ). Table 4: registration update Description Features Requirement Initialization: same Advantage: same registration as registration needs not consider update update During the registration handover: Disadvantage: need when receives to modify the the (add_ip) for to be able to know the and sends the IP of LMA. need to _ACK to inform the, it also send the registration registration to the completion to the location (LMA ) agent registration Discussion about SCTP handover with the location agent If we use mobile IP to initiate the session by toward in SCTP only, we have the following problem. Since we have the with add_ip chunk during the handover, there are the duplicate location registrations. If we use mobile IP, we must send the binding update to HA through FA in the layer 3. With the route optimization option, we have also to send the binding update to via HA. In layer 4 (SCTP), we send the with add_ip to inform the new IP to. Figure 3 depicts the registration with sending with add_ip when the SCTP with MIP is used. Figure 2 shows the registration timeline. In the Figure 2, Location Mgt Broker represents LMA. Figure 3: SCTP with MIP: registration with sending 7534

4 Therefore, we make a location registration twice when we use the SCTP with MIP. This will make bad effects on the performance of the SCTP handover process. To get rid of this anomaly, we can consider following two scenarios. One is not to send (add_ip) to when we use the MIP. The other is not to use the MIP for the location. Figure 4 depicts the registration without sending with add_ip when the SCTP with MIP is used. Step 4: sends the binding update to LMB (IP = L) which it already knows. Step 5: When the LMB receives the BU (binding update: x y), new IP in BU might not be in the domain which it covers, and then it stores the BU and forwards to the other LMB covering that new IP address. Otherwise, it binds the home address (x) and new address (y). Step 6: moves to the other domain. And it sends the BU (x z). Thus, the LMB stores the BU on its own database and relays it to the other LMB. The binding data will be lost after the life time. Step 7: When the INIT chunk of SCTP (over x or y) to require the connection setup with the arrives at the gateway (This is performed by the regular routing on the basis of the destination address: x or y), The LMB looks up the database, and then finds out the current location (z). Step 8: The LMB establishes the tunnel with the current address (z) and forwards the INIT from to. Step 9: extracts the INIT chuck and replies with the INIT- ACK of SCTP. At this time, sends the INIT-ACK with the set_ip_primary (new IP address = z) Figure 4: SCTP with MIP: registration without sending Now, we use the SCTP over MIP with the route optimization. Through this method, we can achieve both the location in the HA and the reduction of SCTP handover delay. (1) We obtain the new IP address by using the MIP and send the binding update with the new IP address to HA and by using the route optimization. (2) MIP of passes new IP address to the SCTP. (3) SCTP adds the new IP address to its IP_list. (4) SCTP sends the _ACK (add_ip) to. Discussion about SCTP handover without the location agent Figure 5 represents the location agent operation when the SCTP without MIP is used. In the Figure 5, LMB (location broker) represents LMA (location agent). LMA performs the following steps: Step 1: receives the IP address of LMB attached to GW (gateway) which covers several ARs (access router) through RA (route advertisement) from AR1. ARs know the IP address of LMB or can use the IP broadcast packet to obtain the IP address of LMB. Step 2: sends the RR (registration request: ID of, home IP address of = x) by using the UDP. In the MIP, RR is composed of the home address of, address of HA, and care-of-address of. MIP uses the UDP port number 434 for RR. Step 3: After moves into the overlapped region, it configures new IP address (y) by using stateless IP configuration (IPv6) or stateful configuration (DHCP). AR1 INIT chunk Domain 1 (:x-y-z) Domain 2 (:z) GW: LMB (IP: L) GW: LMB (IP: M) AR2 tunneling INIT ACK Set primary AR3 x y z Figure 5: SCTP without MIP: location agent During association, receiving the withadd_ip will sends the BU to the corresponding LMB. In order to do this, should know the IP address of LMB. Thus, we will send the with add_ip containing the IP address of the corresponding LMB. Figure 6 depicts the modified packet including IP address of the LMB (LMA). 7535

5 32 bit Source port=3000 Destination Port=80 Verification Tag =0x1000 Checksum Type=0xc1 Flags Length Serial Number Type=0xc001(add_ip) Length = 16 C-ID=0x (correlation id) Type =5 (6: ipv6) Length = 8 value =0x0a ( ) MAC address, prefix_of_router, Visit_count, visit_time, IP address of Location Management Broker flag to requet to send the Binding Update Type=0xc004(set_primary) Length=16 C-ID = 0x Type=5 Length =8 Value = 0x0a ( ) SCTP Common header add_ip extension Set_primary _ip Figure 6: Modification of with add_ip containing IP address of LMA CONCLUSIONS Location problem is one of most important topics in the recent mobile network. Since the latency for reconfiguring IP address during handover increases, the performance degradation of network occurs. To handle this problem, we first survey the related mobility and location schemes including MIPv4 and MIPv6. We then propose the location agent performing the binding update to reduce the handover delay in the SCTP address reconfiguration. The modification of SCTP packet format to support our proposed agent is also proposed. In the future, the performance evaluation for the proposed scheme will be expected. [4] Yegin, A., Supporting Optimized Handover for IP Mobility Requirements for Underlying Systems, <draft-manyfolks-12-mobilereq-02.txt>, Dec., [5] Tan, P., Recommendation for Achieving Seamless IPv6 Handover in IEEE Networks, <draftpaultan-seamless-ipv6-handover txt>, Feb., [6] Montavont, N. and Noel, T., Analysis and Evaluation of Mobile IPv6 Handovers over wireless LAN, Mobile Networks and Applications, Vol. 8, No. 6, 2003, pp [7] Daley, G., Movement Detection Optimization in Mobile IPV6, <draft-delay-mobileip-movedetect- 01.txt>, May, [8] Gwon, Y., Enhanced Forwarding from Previous Care-of-Address for Fast Mobile IPV6 handover, Proceedings of IEEE Wireless Communications and Networking Conference (WC-2004), 2004, pp [9] Montavont, N., Analysis and Evaluation of Mobile IPV6 Handovers over wireless LAN, Mobile Networks and Applications, 8, 2003, pp [10] Fu, S. and Atiquzzaman, M., SCTP: State of the art in research, products, and technical challenges, IEEE Communications Magazine, Vol. 42, No. 4, 2004, pp [11] Stewart, R. and Xie, Q., Stream Control Transmission Protocol (SCTP) A Reference Guide, Addison-Wesley, [12] Stewart, R., SCTP Dynamic Address Reconfiguration, <draft-ietf-tsvwg-addip-sctp- 07.txt>, Feb., [13] Lee, Y., 2014, On the Layer based seamless handover schemes for mobile data network, Advances in Computer Science, Vol. 3, Issue 6, No. 12, November, pp [14] Lee, Y., 2014, History based Handover Broker Scheme for SCTP, Advances in Computer Science, Vol. 4, Issue 3, No. 15, May, pp [15] Lee, Y., 2015, Location Management Broker Scheme for SCTP Handover, International Journal of Engineering Innovation & Research, Vol.43, Issue 3, pp REFERENCES [1] Perkins, C. E., Mobile IP, Addison-Wesley, 1998, pp [2] Widmer, J., Network Simulations for a mobile network architecture for vehicles, TR , International Computer Science Institute, UC Berkeley, [3] Gowasmi, S., Simultaneous Handover in Mobile- IPv4 and , <draft-gowasmi-mobileipsimultaneous-handover-v4-00.txt>, Sep.,