Transition From Ipv4 to Ipv6

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INTERNATIONAL JOURNAL OF ELECTRONICS ANDCOMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)

ISSN 0976 –6464(Print) ISSN0976 –

6472(Online)Volume 4, Issue 5, September – October, 2013,pp. 169-176 © IAEME: www.iaeme.com/ijecet.asp

Journal Impact Factor (2013): 5.8896 (Calculatedby GISI) www.jifactor.com

IJECET

© I A E M E



TRA

NSI

TIO

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FRO

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IPV

4

TO

IPV

6

Chirag

Mulchandani,

Kinjal Mistry,

Purva Chawan,

Abhishek Shetty

Electr

onics

and

Teleco

mmunication

Engin

eering,

D.J.Sang

hviCollegeo

f Engineering

ABSTRAC

T

Curr

ently IPv4is facing theproblem of addressexhaustionand it hasbecome anecessity tomake atransition toIPv6.However,

thedeploymentof IPv6 hasbeenhappeningat a slowrate evenafter itpromises toprovideenhancements to IPv4.

The mainaim of thispaper is topresentinformationabout thetransitionprocessfrom IPv4to IPv6.Initially, thepaper statestheprominentfeatures of IPv4 andIPv6 andalsomentionsthelimitationsof IPv4whichcreated a

platf orm f or the nee

d of transit

ion to IPv6.

Italso discu

sses the advantages of IPv6.Finally, it explains the transitionmechanisms specified byInternet Engineering Task Force(IETF) along with theiradvantages and disadvantages.

Keywords: IPv4, IPv6, IP sec,routing infrastructure, dualstack mechanism, tunnellingmechanism, translationalmechanism, protocol translation(PT)

INTRODUCTION

Internet plays a very bigrole in the lives of individuals bymaking information available in a

quick and easy manner. Internet

has revolutionized the world of communication. It hasfundamentally changed lives of

individuals and business operatorsin the developed world. With thishuge growth in the internet, thereis an increased demand for better,faster and efficient technology.This has increased the demand foraddresses required for sendingand receiving information.

Internet Protocol version

6 (IPv6) is the latest revision of the Internet Protocol (IP) whichwas developed by the InternetEngineering Task Force (IETF).It was mainly developed to dealwith the problem of addressexhaustion faced by IPV4. Withthe increase in the use of Internet-based resourcesglobally and the shift of circuitswitched technologies to IPbased technologies in variousCommunication Networks, theproblem of address exhaustionin IP4 is getting worse.

The current version of Internet Protocol (IPv4) has notsubstantially changed in the past20 years. In this span of time,IPv4 has witnessed robustness,easy implementation,interoperability andaccommodation of rapidlygrowing internet. However, thecontinued expeditious growth of



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International Journal of Electronics and Communication Engineering & Technology (IJE CET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © I AEME

Internet enabled devices and the emerging necessity for secure transfer of data oveer the Internetare surpassing the capabilities of IPv4 a nd are setting limitations.

INTERNET PROTOCOL VERSION 4(IPv4)

Internet Protocol version 4 (IPv4) is the fourth version of the Internet Protocol (IP). It is oneof the core protocols of inter-netwo rking methods of the Internet, and most traffic is routed by it.Being a connectionless protocol, IP v4 is used on packet-switched networks. It do es not guaranteepacket delivery, or proper sequencing of data. These aspects are addressed by an upper layer, suchas Transmission Control Protocol.The following are some important fe atures of IPv4:

Addressing: IPv4 addresses are made up of 32 bits, which allows a total of 4294967296 (2^32)addresses. This number was not en ough and as users were assigned addresses, it gave rise to IPv4address exhaustion. In IPv4, special address blocks are reserved for multicast addresses (~270million addresses) and private netwo rks (~18 million addresses).

Packet Header: Ipv4 has a 32-bit packet header which contains 20 bytes of information. Theheader has variable length which depends on whether the Options field is used or n ot. An IPpacket comprises of two sections: Header a nd Data. The IPv4 packet header comprises of 14fields. Out of these, 13 are required. The 14th fi eld named 'Options' is optional. In the packetheader, the most significant byte is packed first. In th e 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 beetweenoverheads of small packets and line seizure by large packets.

Address Allocation: Address alloca tion is done using network classes: A, B and C. Local use ofaddress is limited to the link. There i s no room for expansion due to exhaustion of c urrentaddresses. Address notation: Ipv4 addresses w hich are 32-bit integers values can be expressed inany notation, but for human convenience, they are often written in dot-decimal, which has four octets expressed in decimal and separated by periods.

Address Types:

Different types of addressesare: 1.) Point to point address2.) Local broadcast and limited multicast

3.) Experimental any cast (not widely available)

Fragmentation: The routers perform multiple step fragmentation of packets fo r the sake of the receiver, but this affects router performance.

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International Journal of Electronics and Communication Engineering & Technology (IJE CET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 5, September – October (2013), © I AEME

Security: Security in IPv4 is limit ed as no authentication or encryption is done at IP level. Thismakes it more dependent on higher level protocols, making it more vulnerable to address deceptionand denial of service attacks.

INTERNET PROTOCOL VERSION 6 (IPv6)

Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP). Itwas developed by the IETF as a solu tion to the problem of address exhaustion in IP v4.

For a device to communicate with other devices using the internet, it must be assign ed an IPaddress. As the number of devices on the Internet increased, the need for more addresses thanexistent ones arose.

Addressing: IPv6 has a 128-bit add ress, which accommodates 2^128 or around 3.4 ×10^38addresses. Packet Header: Packet header in IP v6 is of fixed size: 40 octets. This increasesefficiency of the network.A packet in IPv6 has the following parts: a header and a payload.

The header comprises of a fixed p art with minimal functionality that packets req uire and may beextended for special features.

F igure 2: IPv6 Packet Header

Packet Size: As in IPv4, normal pa ckets having up to 65536(2^16-1) octets are h andled.However, the concept of jumbo grams is introduced in IPv6, which are packe ts with up to4294967295 (2^32−1) octets. These can also be handled. This improves performa nce over a high-MTU link.

Address Allocation: In IPv6, add ress allocation is hierarchical by provider, reg istry, subscriber,subnet and geographical region. Link as well as site is allowed the local use of address.Approximately 70% of the total add resses are reserved for use in future.

Address notation: IPv6 addresses a re expressed in the hexadecimal form. It consists of eightgroups 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:

1.) Multicast – many interfaces can be sent data at once

2.) Anycast – one of the several grou ps of interfaces is sent data

Fragmentation: Here, fragmentation is done by the host and not router. It can be do ne not morethan once. The host checks MTU over the link before performing fragmentation. The ro uterperformance is thus improved.

Security: IPv6 conducts authentication as well as encryption. In addition to this, securityassociations are administered to han dle key distribution.

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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 deviceson 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 bitcapacity and hence some organizations are forced to use NAT (Network Address Translation) inorder to map multiple private addresses into a single public IP address. The primary reason forexhaustion of IPv4 addresses is inadequate design capacity of the initial Internet infrastructure.However, additional driving factors have worsened the shortcomings. Increased Internetdeployment, new and advanced devices for network, etc are few factors that have raised thedemands for IPv4 addresses. The exhaustion of IPv4 addresses can have various effects in differentparts of the world. The effects can trigger the change rapidly in developing economies.

II.) Complexity of configuration: Present IPv4 must be manually configured. Implementation canalso be done using a state full address configuration protocol like Dynamic Host ConfigurationProtocol. As more computers and devices use IP, there is a requirement for an easier and higherautomatic configuration of addresses that are independent of the administration of a DHCPinfrastructure.

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 arerequired to maintain irrationally large number of routing tables. The large routing tables have over85,000 specified routes. Current IPv4 infrastructure has both, flat and hierarchical routing.

IV.) Security: Internet supports private communication over a public medium. Hence, securitycalls for encryption services that should protect the data that is being sent from being viewed orbeing modified in the transmission. The rapidly increasing hostile environment on the internetdemands 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 andonline video libraries and video conferences. This type of communication requires real time datatransfer service. These services require TCP (Transmission Control Protocol) or UDP (User Data-gram Protocol). Real-time traffic support depends on the IPv4 Type of Service (ToS) field but ithas limited functionality. When the IPv4 packet payload is encrypted, Payload identification usinga 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. Italso 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 spacecan 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 thenearest 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 theanycast group, it will be delivered to all the addresses given by that address). Hence, there is

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transmission of a single data packet to multiple receivers. Multimedia applications can takeadvantage of multicast

III.) Hierarchical routing infrastructure: Global addresses are designed to be hierarchical thatleads to relatively few routing entries of the routing tables of the Internet backbone routers. Fasterrouting 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 tothe large address space.

IV.) Automatic Configuration: IPv6 supports two configurations, the state full addressconfiguration (with DHCP) and stateless address configuration (without DHCP automaticconfiguration). Hence, IPv6 hosts can configure themselves automatically in the absence of anaddress configuration infrastructure using stateless address configuration.

V.) Improved Security: IPv6 requires support for IPsec. IPsec is a framework of open standardsdeveloped by the Internet Engineering Task Force and functions at a low-level in the layersbetween the physical wire and a software application. Support for IP sec promotes interoperabilitybetween 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 twoprotocols as majority of hosts and routers currently use IPv4 and it is not feasible to make acomplete switch in a short span of time. Also Network protocol transitions require significantinvestment and work, and with the exhaustion of IPv4 addresses mounting, there is lack of time tocomplete the full IPv6 transition.

The techniques through which IPv6 hosts and routers can interoperate with IPv4 hosts andemploy 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 theend 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



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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.

3.) Allows communication only between similar network nodes i.e. IPv6-IPv6 or IPv4-IPv4.

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.

2.) Best technique for older legacy equipment.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.

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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 translationfrom 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 Ipv6users only.

2.) IPv4 Network infrastructure need not be changed substantially to provide services to

IPv6 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 ishighly 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 completelyseparate networks with hosts and routers having two separate protocol stacks in case devices needto 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 thatincludes 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 namemapping which is an essential part of daily administrations over the internet is impossible to carryout 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.



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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 limitationsmakes 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, theneed for the flexibility extended by IPv6 will be very important. However, transition from IPv4 toIPv6 at an instant is not possible due to the large number of IPv4 users. Taking into account therisks of this immigration a serious challenge is presented to the technologists, which whenaccomplished successfully should defeat the difficulties.

REFERENCES

[1]. IPv6: Theory, Protocol, and Practice, 2nd Edition(The Morgan Kaufmann Series inNetworking)

[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 andReviews in Computer Science (IJRRCS)

[9]. Fahim A. Ahmed Ghanem And Vilas M. Thakare, “Optimization of IPv6 Packet’s HeadersOver Ethernet Frame”, International Journal of Electronics and CommunicationEngineering & 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 CommunicationEngineering & 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 theCurrent IPv4 Packet Headers”, International Journal of Electronics and CommunicationEngineering & Technology (IJECET), Volume 4, Issue 3, 2013, pp. 202 - 210, ISSN Print:0976- 6464, ISSN Online: 0976 –6472.

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Transition From Ipv4 to Ipv6

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