Comparing Mobile IP, TCP/IP and IPv6 - Case Study Example

Comparing Mobile IP, TCP/IP and IPv6 Section Number of Comparing Mobile IP, TCP/IP and IPv6 How TCP/IP works The Transmission Control Protocol/Internet Protocol suite or simply Internet protocols is the foundation on which the Internet and the World Wide Web (WWW) operates. The Transmission Control Protocol/Internet Protocol (TCP/IP) suite has become the industry-standard method of interconnecting hosts, networks, and the Internet. As such, it is seen as the engine behind the Internet and networks worldwide (Parziale, et. al., 2006:1). Actually, the Internet Protocols or TCP/IP Protocols, as they are referred to, are a suite of communication protocols of which the Transmission Control Protocol and the Internet Protocol are the most well known. The entire suite of Protocols has therefore been named as the TCP/IP protocols. The Internet Protocol Suite not only specify protocols lower layer protocols such as TCP and IP but also specifies common applications such as electronic mail, terminal emulation and file transfer. The TCP/IP protocols are the world’s most popular non-proprietary protocol suite because they can be applied to communicate over any set of interconnected networks and are equally adoptable both for LAN and WAN environments. The TCP/IP protocols are best explained illustratively in terms of an architectural model that is used as a common frame of reference for discussing communications over the Internet. An architectural model separates the functions of the communication protocols into manageable layers stacked on top of each other. Each layer of the stack performs a specific function in the process of communicating over the network. The layers are therefore defined in terms of their functions that may be performed not by a single but by a number of protocols. Any architectural model would comprise the four basic layers – Application Layer, Transport Layer, Internetwork or Network Layer, and Network Interface Layer. In a traditional network environment, Internet Protocol (IP) is a Network Layer protocol whereas the Transport Control Protocol (TCP) is a Transport Layer protocol. This layer is responsible for routing messages through internetworks. It is not concerned with data reliability. The Transport Layer, on the other hand, is responsible for providing end-to-end data integrity, and provides a highly reliable communication service in extended two-way conversation over networks. IP controls addressing information and some control information so that routing of data packets is possible. IP therefore has two primary functions: i. Providing unreliable, connectionless, best-effort delivery of datagrams through an internetwork. Best-effort implies that packets sent by IP might be lost, reach non-sequentially, or may even be duplicated. IP leaves it to the higher layer protocols to address these anomalies. Connectionless means that IP does not exchange control information, called a handshake, to establish end-to-end connection before sending data. Data, along with a header and a trailer, are called datagrams. Information such as destination address that is required to route the data is contained in the data header. The header may also contain other data information source address and security labels. Trailers are used to ensure that the data has not been modified in transit. This is typically done through a checksum value in the trailer. ii. IP also fragments and reassembles datagrams so that data links with different Maximum Unit Transmission (MTU) sizes in internetworks may be supported. IP, along with TCP, are the most crucial of the Internet Protocols and are therefore said to represent the heart of the Internet Protocols. The IP addressing scheme is standardized, and is oriented around the process of routing IP datagrams through an internetwork. Each IP address comprises specific components and is of a specified format. Every host on a TCP/IP network is identified by a unique 32-bit logical address. This 32-bit logical address if divided into two parts – the network number and the host number. The network is identified by the network number and is assigned by the Internet Network Information Centre (InterNIC) which is the apex Internet domain registration and IP assigning body. To be a part of the Internet, a network must be assigned the network number by the InterNIC. The InterNIC can also allocate blocks of internet addresses or IP addresses to an Internet Service Provider (ISP) which can in turn assign the addresses as necessary. The host number, on the other hand, identifies a host on the network and is assigned by the network administrator locally. The 32-bit IP address is represented in decimal format known as dotted decimal notation. It is grouped in eight bits at a time, each group separated by dots. Thus, the binary weight of each group in the octet could be 128, 64, 32, 16, 8, 4, 2 and 1. An octet could have a minimum value of 0 and a maximum value of 255. IP networks are broken into smaller networks called subnetworks or subnets. A subnet does not only provide the administrator additional flexibility, but also accords more efficient use of network addresses, and the capability to contain broadcast traffic in a network within the limits of a router. As subnets are under local administration, the network is seen by the external world as a single entity. Detailed knowledge of the organization’s internal structure remains hidden behind the subnets. For example, a network address of 127.10.0.0 can be broken into many subnets such as 127.10.1.0, 127.10.2.0, 127.10.3.0, 127.10.4.0. Bits are borrowed from the host field and designated as the subnet field to create the subnet address. The subnet mask specifies the number of borrowed bits which may vary from subnet to subnet. IP routing is an important function of the IP layer. This function provides the routers the basic mechanism to interconnect different physical networks. IP uses a dynamic routing protocol. This implies that routes are charted automatically at regular intervals by the software in the routing devices depending on the network traffic. This is very unlike static routing where the route is initially established by the network administrator and do not change till the network administrator changes them again irrespective of the pattern of network traffic. Dynamic routing is enabled through an IP table which consists of the destination address or the next hop pair. In IP routing, IP datagrams travel through the network one hop at a time. The entire route is not defined at the beginning of the journey. As the datagram reaches each node, the next route is calculated by matching the destination information in the header with the entry in the node’s routing table. Each node is involved in the routing process to the extent that it forwards the data packets based on internal information. The individual nodes do not monitor whether the packets reaches their final destination or not. This work is done by another protocol called the Internet Control Message Protocol (ICMP). It is the TCP that provides reliable data transmission in an IP environment. TCP provides stream data transfer, reliability, efficient flow control, full duplex operation and multiplexing. In stream data transfer, an unstructured stream of bytes identified by their sequence numbers is delivered by TCP. Reliability is worked into TCP by the provision of connection-oriented, end-to-end reliable packet delivery through a network. TCP establishes a three-way handshake mechanism that allows both the sending and receiving side to agree upon initial sequence numbers. It ensures that each side is ready to transmit and also knows the other side is ready to transmit too. This avoids the transmission or retransmission of packets prior to and after the established transmission session. TCP sequences bytes with a forwarding acknowledgement number that indicates to the destination the next byte that the source expects to receive. When bytes are not acknowledged within a specified time period, they are retransmitted. This mechanism of ensuring reliability in TCP enables devices to adjust for lost, delayed, duplicate or misread packets. TCP also ensures efficient flow control by indicating the highest sequence number that a destination can receive back to the source along with the acknowledgements. Full duplex operation implies that TCP processes can send and receive simultaneously. Similarly, multiplexing indicates that numerous upper layer conversations can be multiplexed over a single connection. Mobile IP In IP networks, routing is based on stationary IP addresses. A device is identified and reached on the network by the IP address specified for it through normal IP routing. But what happens when the device roams from one network to another. Moreover, it is projected that the number of wireless devices for voice of data will soon surpass fixed devices. This scenario is applicable to cellular systems such as 3G and in wireless LAN such as 812.11 and extends to satellite communication. Though link-layer technologies may enable mobility, there will still be problems in terms of data crossing networks or different link layers. The solution lies in Mobile IP – an open-standard protocol defined by the Internet Engineering Task Force (IETF) RFC 2002, that enables users to retain the same IP address, stay connected and maintain ongoing applications while roaming between IP networks. In the overview of Mobile IP, Perkins (1997:84) states that Mobile IP can be thought of as the cooperation of three major subsystems. First, there is a discovery mechanism defined so that mobile computers can determine their new attachment points (new IP addresses) as they move from place to place within the Internet. Second, once the mobile computer knows the IP address at its new attachment point, it registers with an agent representing it at its home network. Lastly, mobile IP defines simple mechanisms to deliver datagrams to the mobile node when it is away from its home network. Mobile IP has three components – Mobile Node, Home Agent and Foreign Agent. The Mobile Node can be any device such as a laptop, cell phone or personal digital assistant with appropriate software that enables roaming capabilities. The Home Agent is a router on the home network which serves as an anchor for communication with the Mobile Node wherever it may be. The Home Agent tunnels data packets from the Correspondent Node or source node – a device on the Internet – to the roaming mobile node. A tunnel is established between the Home Agent and a reachable point for the Mobile Node in the foreign network. The Foreign Agent is a router that functions as the point of attachment for the Mobile Node when it is roaming in a foreign network. The Foreign Agent delivers packets from the Home Agent to the Mobile Node. Mobile IP is achieved through the execution of three phases – Agent Discover, Registration and Tunneling. During the Agent Discovery phase, the Home Agent and the Foreign Agent advertise their services on the network by using ICMP Router Discovery Protocol (IRDP). The mobile node listens to these advertisements to determine whether it is connected to its home network or to a foreign network. Instead of waiting for agents to send the advertisements, the mobile node on its own can also send out a solicitation that forces any agent on the link to immediate send an agent advertisement. Once the mobile node finds out that it is on a foreign network, it acquires a care-of-address. There are two types of care-of-addresses – care-of address acquired from a foreign network and collated care-of address. The care-of address from a Foreign Agent is the IP address of a Foreign Agent that has an interface on the foreign network being visited by the mobile node. It can be shared by more than one mobile node. A collated care-of address, on the other hand, is an IP address temporarily assigned to the interface of the mobile node itself. It can be used by only one mobile node at a time. When a mobile node detects that it is on a foreign network, it starts the Registration process. In the registration process, the mobile node registers its current location with the Foreign Agent and Home Agent. The mobile node sends a registration request with the care-of address that it has acquired to the Home Agent, if required through the Foreign Agent. When the Home Agent receives this request, it either approves the request and adds the necessary information to its routing table, or rejects the request if it is not valid and sends an appropriate error code to the mobile node. The registration process is therefore preceded by an authentication process. The mobile node uses its home IP address to send packets. This effectively maintains the appearance that the mobile node is always on its home network. The mobile nodes movements are transparent to the correspondent nodes even while it is roaming on foreign networks. Data packets addressed to the mobile node are sent to the home network. The Home Agent intercepts these packets and tunnels them to the care-of address of the foreign network in which the mobile node is roaming. Tunneling encapsulates the data to be sent to the end point and de-capsulates the data when it reaches the end point. Mobile IP is scalable because only the mobile node and the end points of the tunnel need to be Mobile IP aware. No other router in the network, or any host with which the mobile node communicates need to be changed or even aware of the movement of the Mobile Node. Implications of IPv6 The coming of IP version 6 (IPv6) brings great advancements in Mobile IP technology. IPv6 includes many features for streamlining mobility support that are missing in IP version 4 (current version), including Stateless Address Autoconfiguration14 and Neighbour Discovery. IPv6 also attempts to drastically simplify the process of renumbering, which could be critical to the future routability of the Internet (Perkins, 1998:64) Route Optimization dramatically improves the performance of IPv6 mobile nodes. In IPv6, when a Correspondent Node knows the mobile node’s current care-of address, it can deliver packet directly to the mobile node’s home address without any assistance from the home agent. Internet Protocol version 6 (IPv6) contains numerous features that make it attractive from a security standpoint (Warfield, 2003:1). There is an overall improvement in security. All IPv6 nodes implement strong authentication and encryption features to improve internal security. IPv6 mobility additionally supports coexistence with Internet ingress filtering, smooth handoffs, renumbering of home networks and automatic home agent discovery. Enhancements such as Mobile IPv6 and Hierarchical Mobile IPv6 (HMIPv6) are being developed to improve mobile communications more secure and more efficient. Interactive Protocol for Mobile Networking (IPMN) envisages supporting mobility on a regular IP network. These development efforts are directed towards creating support for mobile networking without the requirement of any additional infrastructure. Alternative tunnelling protocols such as PPTP and L2TP may pose challenges to mobile IP. Base on PPP, these protocols offer portability to mobile computers. But it is also possible that Mobile IP could recommend the use of such alternative tunnelling protocols to take advantage of their deployment on platforms that do not support IP-within-IP encapsulation as in mobile IP. The total number of mobile subscribers is expected to increase to approximately 3.964 billion by the end of 2011. In the same time frame, the population of the world is likely to increase from approximately 6.5 billion to approximately 7 billion, meaning that worldwide mobile phone penetration should pass the 50% mark some time around the end of 2009 (MobileIN.com Research). The scope of applicability of Mobile IP is therefore infinite. References 1. Parziale, L., Britt, D.T., Davis, C., Forrester, J., Liu, W., Matthews, C. Rosselot, N., TCP/IP Tutorial and Technical Overview, Redbooks, IBM International Technical Support Organization, Eighth Edition. 2006: 1 2. Perkins, C.E., Mobile Networking through Mobile IP, IEEE Internet Computing, 1998:64 3. Perkins, C.E., Mobile IP, IEEE Internet Computing, 1997:84 4. Warfield, M.H., Security Implications of IPv6, Internet Security Systems, 2003:1 5. MobileIN.com Research, Worldwide Mobile Market Forecasts 2006-2011, http://www.mobilein.com/reports/PR/WW_Mobile_Forecasts_2006-2011.php Read More