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40120130405018 2

  1. 1. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – INTERNATIONAL JOURNAL OF ELECTRONICS AND 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET) ISSN 0976 – 6464(Print) ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October, 2013, pp. 169-176 © IAEME: www.iaeme.com/ijecet.asp Journal Impact Factor (2013): 5.8896 (Calculated by GISI) www.jifactor.com IJECET ©IAEME TRANSITION FROM IPV4 TO IPV6 Chirag Mulchandani, Kinjal Mistry, Purva Chawan, Abhishek Shetty Electronics and Telecommunication Engineering, D. J. Sanghvi College of Engineering ABSTRACT Currently IPv4 is facing the problem of address exhaustion and it has become a necessity to make a transition to IPv6. However, the deployment of IPv6 has been happening at a slow rate even after it promises to provide enhancements to IPv4. The main aim of this paper is to present information about the transition process from IPv4 to IPv6. Initially, the paper states the prominent features of IPv4 and IPv6 and also mentions the limitations of IPv4 which created a platform for the need of transition to IPv6. It also discusses the advantages of IPv6. Finally, it explains the transition mechanisms specified by Internet Engineering Task Force (IETF) along with their advantages and disadvantages. Keywords: IPv4, IPv6, IP sec, routing infrastructure, dual stack mechanism, tunnelling mechanism, translational mechanism, protocol translation (PT) INTRODUCTION Internet plays a very big role in the lives of individuals by making information available in a quick and easy manner. Internet has revolutionized the world of communication. It has fundamentally changed lives of individuals and business operators in the developed world. With this huge growth in the internet, there is an increased demand for better, faster and efficient technology. This has increased the demand for addresses required for sending and receiving information. Internet Protocol version 6 (IPv6) is the latest revision of the Internet Protocol (IP) which was developed by the Internet Engineering Task Force (IETF). It was mainly developed to deal with the problem of address exhaustion faced by IPV4. With the increase in the use of Internet-based resources globally and the shift of circuit switched technologies to IP based technologies in various Communication Networks, the problem of address exhaustion in IP4 is getting worse. The current version of Internet Protocol (IPv4) has not substantially changed in the past 20 years. In this span of time, IPv4 has witnessed robustness, easy implementation, interoperability and accommodation of rapidly growing internet. However, the continued expeditious growth of the 169
  2. 2. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – Engineering 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME Internet enabled devices and the em emerging necessity for secure transfer of data over the Internet are surpassing the capabilities of IPv4 and are setting limitations. INTERNET PROTOCOL VERSION 4(IPv4) 4 Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is one of the core protocols of inter-networking methods of the Internet, and most traffic is routed by it. networking Being a connectionless protocol, IPv4 is used on packet-switched networks. It does not guarantee packet delivery, or proper sequencing of data. These aspects are addressed by an up upper layer, such as Transmission Control Protocol. The following are some important features of IPv4: Addressing: IPv4 addresses are made up of 32 bits, which allows a total of 4294967296 (2^32) addresses. This number was not enough and as users were assigned addresses, it gave rise to IPv4 assigned address exhaustion. In IPv4, special address blocks are reserved for multicast addresses (~270 million addresses) and private networks (~18 million addresses). Packet Header: Ipv4 has a 32-bit packet header which contains 20 bytes of information. The header bit has variable length which depends on whether the Options field is used or not. An IP packet comprises of two sections: Header and Data. The IPv4 packet header comprises of 14 fields. Out of these, 13 are required. The 14th field named 'Options' is optional. In the packet header, the most 4th significant byte is packed first. In the table below, this byte is the version field. Figure1: IPv4 Packet Header Packet size: The maximum packet size is 65535 octets. There is a compromise between overheads There of small packets and line seizure by large packets. Address Allocation: Address allocation is done using network classes: A, B and C. Local use of address is limited to the link. There is no room for expansion due to exhaustion of current addresses. Address notation: Ipv4 addresses which are 32-bit integers values can be expressed in any notation, 32 but for human convenience, they are often written in dot-decimal, which has four octets expressed in dot decimal, decimal and separated by periods. Address Types: Different types of addresses are: 1.) Point to point address 2.) Local broadcast and limited multicast 3.) Experimental any cast (not widely available) Fragmentation: The routers perform multiple step fragmentation of packets for the sake of the receiver, but this affects router performance. 170
  3. 3. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – Engineering 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME Security: Security in IPv4 is limited as no authentication or encryption is done at IP level. This makes it more dependent on higher level protocols, making it more vulnerable to address de deception and denial of service attacks. INTERNET PROTOCOL VERSION 6 (IPv6) Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP). It was developed by the IETF as a solution to the problem of address exhaustion in IPv4. IPv For a device to communicate with other devices using the internet, it must be assigned an IP address. As the number of devices on the Internet increased, the need for more addresses than existent ones arose. Addressing: IPv6 has a 128-bit address, which accommodates 2^128 or around 3.4×10^38 addresses. Packet Header: Packet header in IPv6 is of fixed size: 40 octets. This increases efficiency of the network. A packet in IPv6 has the following parts: a header and a payload. The header comprises of a fixed part with minimal functionality that packets require and may be extended for special features. Figure 2: IPv6 Packet Header Packet Size: As in IPv4, normal packets having up to 65536(2^16-1) octets are handled. However, 65536(2^16 1) However the concept of jumbo grams is introduced in IPv6, which are packets with up to 4294967295 (2^32−1) octets. These can also be handled. This improves performance over a high −1) highMTU link. Address Allocation: In IPv6, address allocation is hierarchical by provider, registry, subscriber, subnet and geographical region. Link as well as site is allowed the local use of address. Approximately 70% of the total addresses are reserved for use in future. Address notation: IPv6 addresses are expressed in the hexadecimal form. It consists of eight groups consists of four digits each, separated by colons. Since this is a long and inconvenient way, there exist methods of shorter notation. Address Types: The following are the types of addresses in IPv6: IPv6 1.) Multicast – many interfaces can be sent data at once 2.) Anycast – one of the several groups of interfaces is sent data Fragmentation: Here, fragmentation is done by the host and not router. It can be done not more than once. The host checks MTU over the link before performing fragmentation. The router performance is thus improved. Security: IPv6 conducts authentication as well as encryption. In addition to this, security associations are administered to handle key distribution. 171
  4. 4. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME SHORTCOMINGS OF IPv4 With IPv4 being the most widely deployed Internet protocol that is used to connect devices on the internet, it still has some drawbacks. Some of which are stated below: I.) Exhaustion of IPv4 addresses: With the advancement of the Internet, there is a considerable increase in for Internet addresses, in turn draining the supply of IPv4 addresses. IPv4 has32 bit capacity and hence some organizations are forced to use NAT (Network Address Translation) in order to map multiple private addresses into a single public IP address. The primary reason for exhaustion of IPv4 addresses is inadequate design capacity of the initial Internet infrastructure. However, additional driving factors have worsened the shortcomings. Increased Internet deployment, new and advanced devices for network, etc are few factors that have raised the demands for IPv4 addresses. The exhaustion of IPv4 addresses can have various effects in different parts of the world. The effects can trigger the change rapidly in developing economies. II.) Complexity of configuration: Present IPv4 must be manually configured. Implementation can also be done using a state full address configuration protocol like Dynamic Host Configuration Protocol. As more computers and devices use IP, there is a requirement for an easier and higher automatic configuration of addresses that are independent of the administration of a DHCP infrastructure. III.) Flat Routing Infrastructure: In the initial internet, for creating a hierarchical routing infrastructure, address prefixes were not assigned. Rather, individual access prefixes were allocated. Each address prefix became a new route in the routing tables. As a result, Internet backbone routers are required to maintain irrationally large number of routing tables. The large routing tables have over 85,000 specified routes. Current IPv4 infrastructure has both, flat and hierarchical routing. IV.) Security: Internet supports private communication over a public medium. Hence, security calls for encryption services that should protect the data that is being sent from being viewed or being modified in the transmission. The rapidly increasing hostile environment on the internet demands built in security. V.) Quality of Service (QoS): Presently, Internet users not only limit themselves to web browsing and searching data but also are well acquainted with the text, voice and video chat features and online video libraries and video conferences. This type of communication requires real time data transfer service. These services require TCP (Transmission Control Protocol) or UDP (User Datagram Protocol). Real-time traffic support depends on the IPv4 Type of Service (ToS) field but it has limited functionality. When the IPv4 packet payload is encrypted, Payload identification using a UDP Port is not possible. ADVANTAGES OF IPv6 I.) Large Addressing Space: IPv6 has 128 bit long addresses. Hence, an address space with 3.4 x 1038 addresses is possible. This number of address space is abundant for the anticipated future. It also allows all kinds of devices to connect to the internet not making the use of Network Address Translators (NAT’s) and hence allowing spotless transparent end-to-end security. Address space can be also be assigned internationally. II.) Flexible Addressing Configuration: There are plenty of possibilities for address representation that have structures like multicast, anycast, unicast, etc. The anycast structure is an identifier to a set of interfaces having different nodes. When a packet is sent to an anycast group, it will be delivered to the nearest interface (one of the group members) and hence limiting data flooding The multicast structure is also a set of interfaces, but, unlike anycast, when a packet is sent to the anycast group, it will be delivered to all the addresses given by that address). Hence, there is 172
  5. 5. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME transmission of a single data packet to multiple receivers. Multimedia applications can take advantage of multicast III.) Hierarchical routing infrastructure: Global addresses are designed to be hierarchical that leads to relatively few routing entries of the routing tables of the Internet backbone routers. Faster routing is possible due to the efficient routing table organized with hierarchical routing infrastructure. Hierarchical routing is measurable enough to sustain the growth of internet due to the large address space. IV.) Automatic Configuration: IPv6 supports two configurations, the state full address configuration (with DHCP) and stateless address configuration (without DHCP automatic configuration). Hence, IPv6 hosts can configure themselves automatically in the absence of an address configuration infrastructure using stateless address configuration. V.) Improved Security: IPv6 requires support for IPsec. IPsec is a framework of open standards developed by the Internet Engineering Task Force and functions at a low-level in the layers between the physical wire and a software application. Support for IP sec promotes interoperability between different IPv6 implementations. It also provides standard based solutions for network security demands. THE PROGRESSION FROM IPv4 TO IPv6 The main criteria for smooth transition from IPv4 to IPv6 is compatibility between the two protocols as majority of hosts and routers currently use IPv4 and it is not feasible to make a complete switch in a short span of time. Also Network protocol transitions require significant investment and work, and with the exhaustion of IPv4 addresses mounting, there is lack of time to complete the full IPv6 transition. The techniques through which IPv6 hosts and routers can interoperate with IPv4 hosts and employ the existing IPv4 routing infrastructure are discussed below. I.) Dual Stack Mechanism: Dual Stack refers to TCP/IP capable network equipment that provides support for both IPv4 and IPv6. It means that if the end user isIPv6 ready then IPv6 is used and if the end user is IPv4 ready then IPv4 is used. Both IPv4 and IPv6 protocol stack is run by hosts and routers as specified in IETF RFC2893.Thus, with all new devices to be both IPv6 and IPv4 capable allows these devices to have the capability to use either of the IP versions, depending on the availability of the network, service, and the administrative policy. This means that, for each datagram the router has two routing tables and two routes will be calculated but only one of them will be followed by the packet. The application needs to know that routers have a double stack. Figure3 shows the dual stack mechanism in which IPv4 networks communicate with IPv6 networks. Figure3: Dual Stack Mechanism 173
  6. 6. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME Advantages 1.) Easy to understand and implement. 2.) It is the most direct method for a smooth transition from IPv4 to IPv6. Disadvantages 1.) Decreases the performance of devices. 2.) Network complexity and cost increased. Allows communication only between similar network nodes i.e. IPv6-IPv6 or IPv4-IPv4. 3.) II.) Tunnelling Mechanism: The term “tunnelling” in general refers to a method of enveloping one version of IP in another so the packets can be sent over a network that does not support the enveloped IP version. In other words, tunnelling is used to implement the interconnection between the isolated IPv4 networks distributed in an IPv6 network or the isolated IPv6 islands distributed in an IPv4 network. For example, when two IPv6 islands need to communicate over an IPv4 network, dual stack routers at the network borders can be used to set up a tunnel which envelopes the IPv6 packets within IPv4 thereby allowing the IPv6 networks to communicate without having to modify the IPv4 network infrastructure. Thus, tunnelling facilitates internetworking between IPv6 islands without the up gradation of the entire IPv4 network. The tunnelling mechanism is shown in figure4. Figure4: Tunnelling of IPv6 over IPv4 network Types of tunnels: A.) Configured: In configured tunnels, the network administrators manually configure the tunnel within the endpoint routers at each end. B.) Automatic: In automatic tunnels, the devices create their own tunnels to end point routers for shipping IPv6 packets within IPv4 Advantages: 1.) Easy to implement over existing IP4 network. Best technique for older legacy equipment. 2.) 3.) Easy to use at the early stage of transition. Disadvantages: 1.) Breakdown of tunnel will fail the network. 2.) Creation of tunnel can be costly. III.) Translational Mechanism: As the name suggests, this technique translates the IP packets i.e. from IPv4 to IPv6 and vice versa. Translation devices are located on the edges of two networks. They translate corresponding fields of the IP header and the IP address carried in the packet body. 174
  7. 7. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME Network Address Translation (NAT): The NAT mechanism is an IPv4 to IPv6 translator. Nodes of NAT-PT are at the boundaries between IPv6 and IPv4. When sessions are initiated between IPv4 and IPv6, each NAT-PT node maintains a pool of IPv4 addresses which are globally routable and they are dynamically assigned to IPv6. This mechanism allows native IPv6 hosts and routers to communicate with native IPv4 network devices and vice versa. NAT-PT uses an Application Layer Gateway (ALG) functionality that translates Domain Name System (DNS) mappings between protocols. The translation from IPv4 to IPv6 using NAT-PT router is shown in figure5. Figure5: NAT-PT Translation Mechanism Advantages: 1.) Provides a smooth migration to IPv6 and provides seamless Internet experience to Ipv6 users only. IPv4 Network infrastructure need not be changed substantially to provide services to IPv6 2.) networks. 3.) Cost is low. Disadvantages: 1.) Tie up with ALG functionality causes hindrances to deployment of NAT-PT. 2.) Not supported on end-to-end basis. 3.) Single point of failure. PROBLEMS IN IMPLEMENTING IPv6 Deployment of IPv6 is a big challenge for service providers and stake holders. IPv6 is highly incompatible with IPv4 for deployment at the packet level. Translation services have various practical issues that make it disputed. As a result, IPv4 and IPv6 are treated as completely separate networks with hosts and routers having two separate protocol stacks in case devices need to access both networks. Another challenge is the upgrade jump from 32 bit of IPv4 to 128 bit of IPv6. The implementation of IPv6 is as good as planning to implement a new technology that includes increased project risks. Planning to deploy IPv6 must also take into account the lack of broad experience with protocol. Due to the large size of the IPv6 addressing space, reverse name mapping which is an essential part of daily administrations over the internet is impossible to carry out manually. Hence, it is clear that the complexities in the implementation of IPv6 will require judicious use of time in the transition period from IPv4 to IPv6. 175
  8. 8. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © IAEME CONCLUSION While IPv4 has had an overwhelming durability in the ever increasing networking world, major limitations like the exhaustion of addressing space coupled with other basic limitations makes it essential to implement features of IPv6. With the increased addressing space made possible in the IPv6 addressing scheme, the solution is deploying IPv6. As the number of Internet-based devices continues to increase worldwide at an exponential rate, the increased availability of the internet in remote areas and the use of Internet enabled devices in population dense areas, the need for the flexibility extended by IPv6 will be very important. However, transition from IPv4 to IPv6 at an instant is not possible due to the large number of IPv4 users. Taking into account the risks of this immigration a serious challenge is presented to the technologists, which when accomplished successfully should defeat the difficulties. REFERENCES [1]. IPv6: Theory, Protocol, and Practice, 2nd Edition(The Morgan Kaufmann Series in Networking) [2]. IPv6 essentials- Sylvia Hagen. [3]. RFC 2462: IPv6 Stateless Address Auto configuration [4]. http://pic.dhe.ibm.com/infocenter/iseries/v6r1m0/index.jsp?topic=/rzai2/rzai2compipv4ipv6.htm [5]. www.cisco.com [6]. IPv4/IPv6 Transition Mechanisms--European Journal of Scientific Research [7]. RFC 1933- Transition Mechanisms for IPv6 hosts and routers [8]. IPv6: Current Deployment and Migration Status--International Journal of Research and Reviews in Computer Science (IJRRCS) [9]. Fahim A. Ahmed Ghanem And Vilas M. Thakare, “Optimization of IPv6 Packet’s Headers Over Ethernet Frame”, International Journal of Electronics and Communication Engineering & Technology (IJECET), Volume 4, Issue 1, 2013, pp. 99 - 111, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472. [10]. Fahim A. Ahmed Ghanem and Vilas M. Thakar, “Compatibility Between the New and the Current IPv6 Packet Headers”, International Journal of Electronics and Communication Engineering & Technology (IJECET), Volume 4, Issue 3, 2013, pp. 211 - 219, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472. [11]. Fahim A. Ahmed Ghanem and Vilas M. Thakare, “Compatibility Between the New and the Current IPv4 Packet Headers”, International Journal of Electronics and Communication Engineering & Technology (IJECET), Volume 4, Issue 3, 2013, pp. 202 - 210, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472. 176

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