Mobile Internet Protocol Issues - Essay Example

MOBILE IP Working of Mobile Internet Protocol and its uses. I. Introduction The use of Internet in the daily activities is continuously increased. Moreover, as the demands of the customers change Internet services have also to be developed in order to meet the requirements set by the consumers. In order to explain the development made in the area of Internet Ghosh (2006) states that 'the Internet infrastructure is built on top of a collection of protocols, called the TCP/IP protocol suite. Transmission Control Protocol (TCP) and Internet Protocol (IP) are the core protocols in this suite; IP requires the location of any host connected to the Internet to be uniquely identified by an assigned IP address; This raises one of the most important issues in mobility, because when a host moves to another physical location, it has to change its IP address. However, the higher-level protocols require IP address of a host to be fixed for identifying connections'. IP protocol is therefore a necessary element of the network activities. In this context, many companies that activate in the area of IT technology and especially those which provide network - related services offer to their customers the chance to use Internet even when they are far from their home or office, i.e. when there is a physical distance from the area where the Internet connected device is placed and operate. The particular technology that offers such an advantage is called Mobile IP and it is available by several IT companies including CISCO, IBM, NOKIA and so on, which have included the above technology in their products offering at the same time to the interest customers all the necessary support. II. Mobile IP - definition and characteristics According to a general definition of Mobile IP used by CISCO (2006) 'Mobile IP provides users the freedom to roam beyond their home subnet while consistently maintaining their home IP address; This enables transparent routing of IP data grams to mobile users during their movement, so that data sessions can be initiated to them while they roam; it also enables sessions to be maintained in spite of physical movement between points of attachment to the Internet or other networks'. In the same context, it has been stated that Mobile IP is 'a standard that allows users with mobile devices whose IP addresses are associated with one network to stay connected when moving to a network with a different IP address; When a user leaves the network with which his device is associated (home network) and enters the domain of a foreign network, the foreign network uses the Mobile IP protocol to inform the home network of a care-of address to which all packets for the user's device should be sent. Image 1 - Description of a Mobile IP system (Ghosh, 2006) In a similar definition presented by Chen (2006) 'Mobile IP is an internet protocol designed to support host mobility; Its goal is to provide the ability of a host to stay connected to the internet regardless of their location; Mobile IP is able to track a mobile host without needing to change the mobile host's long-term IP address'. It should be noticed that in accordance with Ollikainen (1999) 'when IP routing was originally defined, mobility of hosts was not considered to be an issue because routing methods were built for static networks, where the hosts were unlikely to move from one subnet to another. Thus, the IP address encodes the computer's physical location, and - by default - the location is fixed'. The main element of Mobile IP is therefore the IP protocol which enables the users to access the Internet even when they are far from the device which is connected with the Internet - the use of a mobile node towards the achievement of such an effort is crucial. It should also be noticed that Mobile IP tends to present a different level of performance in accordance with the system in which it is implemented (i.e. capabilities of the specific system) as well as with the type of protocol using for its formulation and configuration. More specifically, as presented in the Table 1 below, Mobile IP reaches its highest level of performance in a Dynamic type of protocol. Feature Dynamic MosquitoNet Solaris MIP Cellular IP IMHP Compatibility with existing protocols High High Medium Medium Medium Dependency on network support High Low Medium High High Support for Optimal routing Average High Above average Low Above average Support for Security High Low Medium Low High Scalability Highest Above average Average Lowest Average Speed of Handoff Fast Average Average Above Average Slow Overheads High Low Below Average High Average Table 1 Comparison of Mobile IP implementations (Mondal, 2003, in So-In, 2006) III. Standards and protocols of Mobile IP In general terms the Mobile Internet Protocol (Mobile IP) is 'an extension to the Internet Protocol proposed by the Internet Engineering Task Force (IETF) that addresses the issue of change on an IP address of a host moving to another physical location enabling mobile computers to stay connected to the Internet regardless of their location and without changing their IP address' (Ghosh, 2006). It should be noticed however that the above technology is based on the IP Protocol and for this reason its structure has been based on the components and the operation of the above Protocol. The structure and the operation of IP protocol is presented in general in the work of Kiesler (1997, 16-17) who stated that the IP as 'the data to be sent across the network by sorting information into standard packets that can be transmitted; Under IP each "host" machine is given a unique IP "address," a number to which could be attached attendant routing information'. Using a mathematical type, Mobile IP can be described as follows: In the above mathematical type that has been included in the study of Wu et al. (2004, 1485) there are a series of elements used in order to represent the Mobile IP in practical terms. As for the particular elements used, they can be explained as follows: 'HA4, FA and MH4 are the model for home agents, foreign agents and mobile hosts in Mobile IP, respectively; nha, nfa, and nmh are the number of home agents, foreign agents and mobile hosts, respectively' (Wu et al., 2004, 1485) Furthermore, Mobile IP may appear through similar forms offering certain differentiations in the services provided under normal conditions. In this context, Transparent Mobile IP (TMip) aims 'to provide IP mobility across multiple networks, ensuring that all active TCP sessions will be maintained upon client migration; No client-side software or alteration to the IP stack is required; The network itself changes to provide connectivity to hosts, using IP tunneling techniques' (Transparent Mobile IP, 2003) IV. Implementation of Mobile IP Generally, in order to enable Mobile IP services one has to determine not only 'which home agents will facilitate the tunneling for selected IP address, but also where these devices or hosts will be allowed to roam while the areas, or subnets, into which the hosts will be allowed to roam will determine where Foreign Agent services need to be set up' (CISCO, 2006) At a first level it has to be noticed that 'IP version 4 assumes; that a node's IP address uniquely identifies its physical attachment to the Internet; Therefore, when a corespondent host (CH) tries to send a packet to a mobile node (MN), that packet is routed to the MN's home network, independently of the current attachment of that MN (this is because CHs do not have any knowledge of mobility)' (Introduction to Mobile IP, 2006). On the other hand, 'when the MN is on its home network, and a CH sends packets to the mobile node, the Mobile Node obtains those packets and answers them as a normal host (this is one important requirement in Mobile IP), but if the MN is away from its home network, it needs an agent to work on behalf of it: That agent is called Home Agent (HA) and it is especially beneficial in environments where wireless LANs are used, since it allows seamless transition between base stations, since the tunneling of datagrams hides the movement of the host' (CISCO, 2006) In order to enable Home Agent service for users having homed or virtually homed IP addresses on the router, one has to follow the steps presented in Table 1 which are part of the implementation process of Mobile IP (specifically in the case of Home Agent service). Step Command Purpose 1. router mobile Enable Mobile IP on the router. 2. ip mobile home-agent Enable home agent service. 3. ip mobile virtual-network addr mask Add virtual network to routing table. If not using a virtual network, skip to step6. 4. router protocol redistribute mobile Enable redistribution of virtual network into routing protocol(s). 5. ip mobile host lower [upper] virtual-network addr mask [aaa [load-sa]] Specify mobile nodes (on virtual network) and where their security associations are stored.1 6. ip mobile host lower [upper] {interface name} Specify mobile nodes on interface and where their security associations are stored. Skip this step if there are no mobile nodes on the interface. 7. ip mobile secure host addr {inbound-spi spi-in outbound-spi spi-out | spi spi} key hex string Set up mobile hosts' security associations. Skip this step if using AAA. 8. ip mobile secure foreign-agent addr {inbound-spi spi-in outbound-spi spi-out | spi spi} key hex string (Optional) Set up foreign agents' security associations. Skip this step unless you have security association with remote foreign agents. Table 2 - Steps of implementation of Mobile IP for a home agent service (CISCO, 2006) As of its structure, the Home Agent can be described as follows: The above form that is presented in the study of Wu et al. (2004, 1486) can lead to different types of Mobile IP in accordance with the prices given in the elements used for its formulation. These elements are analysed in the Appendix section (number I of the tables presented in the specific section). On the other hand Foreign Agent services 'need to be enabled on a router attached to any subnet into which a mobile node may be roaming; for administrators wanting to utilize roaming between wireless LANs, Foreign Agent functionality would be configured on routers connected to each base station' (CISCO, 2006). The steps of the implementation process for the Foreign Agent services of Mobile IP are presented in Table 2. Step Command Purpose 1. router mobile Enable Mobile IP on the router. 2. ip mobile foreign-agent care-of interface Set up care-of address(es) advertised to all foreign agent-enabled interfaces. 3. Ip mobile foreign-service Enable foreign agent service on the interface. 4. ip mobile secure home-agent addr {inbound-spi spi-in outbound-spi spi-out | spi spi} key hex string (Optional) Set up home agent security association (optional). Skip steps 4 and 5 unless you have security association with remote home agents or visitors. 5. ip mobile secure visitor addr {inbound-spi spi-in outbound-spi spi-out | spi spi} key hex string [replay timestamp] (Optional) Set up visitor security association. Table 3 - Steps of implementation of Mobile IP for a Foreign agent service (CISCO, 2006) The foreign agent can be formally described as follows (Wu et al., 2004, 1486): The particular elements of this mathematical type are analyzed in the Appendix Section (Appendix II). V. Future Developments in Mobile IP The next version of IP, IPv6 is designed to be 'an evolutionary step from IPv4' while its addresses are '128 bits long; Mobility support in IPv6 solves many of the problems of basic Mobile IP; Some advantages of Mobile IPv6 over Mobile IPv4 are: a) Route Optimization is built as a fundamental part of Mobile IPv6 unlike Mobile IPv4 where it is an optional set of extensions that may not be supported by all nodes, b) Foreign Agents are not needed in Mobile IPv6. The enhanced features of IPv6 like Neighbor Discovery and Address Auto configuration enable mobile nodes to function in any location without the services of any special router in that location, c) In Mobile IPv4, when a mobile node communicates with a correspondent node, it puts its home address as the source address of the packet; This problem is tackled in Mobile IPv6 by putting the care-of address as the source address and having a Home Address Destination option, allowing the use of the care-of address to be transparent over the IP layer' (Ghosh, 2006, Johnson et al., 2000) On the other hand, it has been noticed that IPv6 'will include support for 3G UMTS/GPRS networks and IPSec based security while the Future releases for MIPv4 will incorporate optimized routing methods. Support for SKIP based firewall traversal will be provided' (Mobile IP, 2006). Moreover, because of the continuous development of the technology it is very likely that another version of Mobile IP will be introduced in order to provide a more completed tool of Internet connection avoiding in the same time the pitfalls of the previous versions of this technology. VI. Uses of Mobile IP Mobile IP is most useful in environments where 'mobility is desired and the traditional land line dial-in model or DHCP do not provide adequate solutions for the needs of the users' If it is necessary or desirable for a user to maintain a single address while they transition between networks and network media, Mobile IP can provide them with this ability; Generally, Mobile IP is most useful in environments where a wireless technology is being utilized (CISCO, 2006). On the other hand, it has been proved that Mobile IP is most often found in 'wireless WAN environments where users need to carry their mobile devices across multiple LANs with different IP addresses' (Mobile IP, 2006). Tschudin (1997, in Kotz et al., 2002) noted that 'there are many layers in which mobile agents and mobile code might be useful. Mobile code is most frequently discussed in the application layer, but in many cases it might be more valuable inside a middleware layer, supporting more conventional applications'. Conclusion According to Chen (2006) Mobile IP is 'a newly defined protocol which supports mobile users but also is compatible with the current IP; it is still in the process of being standardized, and there are still many items that need to be worked on and enhanced, such as the security issue and the routing issue'. The use of Mobile IP in the modern IT market cannot be denied. However, it is in any case an issue that should be evaluated in accordance with the real demands of the users while the existence of the appropriate conditions (existed IT technology, financial strength of the interested user etc.) should be always examined thoroughly in advance. Moreover, the presentation of the advantages and the pitfalls of Mobile IP technology has proved that the above technology is not free of negative prospects. A more thoroughly examination of the relevant issue could even present more disadvantages of the specific technology. However, the most important characteristic of Mobile Technology is that it can offer to its users a significant service: the ability to access the Internet from distance and when this demand is of significant importance for the interested user, then the above technology should be considered as achieved the target set by its provider. References CISCO (2006) 'Documentation', available at http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t1/mobileip.htm Chen, Y. (2006) 'A survey paper on Mobile IP', available at http://www.cs.wustl.edu/jain/cis788-95/ftp/mobile_ip/index.html Dang, Z., Kemmerer, R.A. (1999): Using the astral model checker to analyze mobile IP. In: 21st International Conference on Software Engineering, Los Angeles, California, United States, IEEE Computer Society Press, 132-141 Dommety, G., Leung, K. (2001). 'Mobile IP Vendor/Organization-Specific Extensions', available at ftp://ftp.isi.edu/in-notes/rfc3115.txt Ghosh, D. (2006) 'Mobile IP', available at http://www.acm.org/crossroads/xrds7-2/mobileip.html Introduction to Mobile IP (2006), available at http://www.hpl.hp.com/personal/Jean_Tourrilhes/MobileIP/ppal.html Kantarjiev, C. (1993). 'Experiences with X in a Wireless Environment' Proc. USENIX Mobile and Location Independent Computing Symposium, 117-28 Kiesler, S. (1997). 'Culture of the Internet' Lawrence Erlbaum Associates. Mahwah, NJ Kotz, D., Gray, R., Rus, D. (2002). 'Future Directions for Mobile Agent Research' DS Online Exclusive, August McCann, P., Roman, G. (1999) 'Modeling mobile IP in mobile UNITY' ACM Transaction on Software Engineering and Methodology, 8: 115-146 Mobile IP (2006), available at http://www.webopedia.com/TERM/M/Mobile_IP.html Mobile IP Overview (2006), available at http://www.cse.wustl.edu/jain/cis788-95/mobile_ip/index.html Mondal, A. S. (2003). 'Mobile IP - Present State and Future', Series in Computer Science, Kluwer Academic/ Plenum Publishers Ollikainen, V. (1999). 'Mobile IP explained', available at http://www.tml.tkk.fi/Opinnot/Tik-111.550/1999/Esitelmat/MobileIP/Mobip.html#TUsing_PPP_in_mobile_IP Perkins, C., Calhoun, P. (2000). 'Mobile IPv4 Challenge/Response Extensions', available at ftp://ftp.isi.edu/in-notes/rfc3012.txt Raab, S., Chandra, W. (2005) 'Mobile IP Technology and Applications' Cisco Press Transparent Mobile IP, Development Branch (2003), available at http://freshmeat.net/projects/tmip/ Tschudin, C. (1997). "Open Resource Allocation for Mobile Code," Springer-Verlag, Berlin, Germany, 1219: 186-197 Wu, P., Zhang, D. (2004). 'Compositional Analysis of Mobile IP with Symbolic Transition Graphs' Institute of Software, Chinese Academy of Sciences, proceedings of ICCC2004 Appendix I (Wu et al., 2004, 1486) Appendix II (Wu et al., 2004, 1486) Read More