The rapid growth of internet user creates challenges for the internet management groups and the service providers. Everyday infrastructure of internet is expending and we surf internet everywhere even in remote area. Increased of usage also increase online devices. comScore Network announced in March 2007 that ", today announced that 747 million people, age 15+, used the Internet worldwide in January 2007, a 10-percent increase versus January 2006" and we will a brief description in appendix 1 of internet users growth from "comScore Network" . Since then internet usage is increasingly growing. In addition we have started with internet protocol addressing called IPv4 and design just for 32 bit address which can support total number of device 4,294,967,296 and nobody thought that this slot will be full.
Beside the 4 billion addressing is getting full we have another problem in IPv4 which is security at IP Level: When we communicate at unrestricted medium we have to encrypt data to conserve security and privacy. After a passage of time we have now security for IPv4 packets. This security knows as internet protocol security or IPSec but this is not compulsory for IPv4.
Furthermore we have to concern with the quality of service in IPv4 because today the user of internet is not limited with browsing and searching of data only; but users are well aware of text and voice and video conference and online video libraries so these communication need real time data transfer for quality of service and we use UDP (User Data-gram Protocol) or TCP (Transmission Control Protocol).IPv4 TOS field has incomplete functionality and, over time, has been redefined and locally interpreted. Additionally, payload identification that uses a TCP or UDP port is not possible when the IPv4 packet payload is encrypted.
Finally IPv4 challenge many problem we have recite them above and clearly that we must change this Internet Protocol and migrate to IPv6 that was publish in December 1998 to solve most of challenges of the IPv4 specially the address with 128 bit that can support 3.4Ã-1038 address, This expansion provides flexibility in allocating addresses and routing traffic and eliminates the primary need for network address translation (NAT).
Migration technology overview:
The transition between the IPv4 Internet in the present day and the IPv6 Internet of the upcoming days will be a long process. A mechanism for ensuring soft, stepwise and independent switch to IPv6 services is required such a mechanism must help the seamless coexistence of IPv4 and IPv6 nodes during the transition time. A different method of technology exists to facilitate the migration to IPv6 these technologies will be discussed above according to the basic categories.
IPv4/IPv6 Dual-Stack Mechanism
It's recommended that all host before migrating completely from IPv4 to IPv6, have a dual stack of protocol; that's mean, a station must operate in both IPv4 and IPv6 in parallel until all the internet use IPv6. See the above figure 1 for the layout of dual stack configuration
(Figure 1)
The Dual-stack capabilities of set of connections nodes support the transport of both IPv4 and IPv6 packets. IPv4 applications use the IPv4 stack, and IPv6 applications use the IPv6 stack.
Flow decisions are based on the version field of IP header for the receiver, and on the destination
Address type for sending. The types of addresses are usually derived from DNS lookups; the
Suitable stack is selected in response to the types of DNS records returned. If the DNS return an IPv4 address, the source host send an IPv4 and it will be the same as IPv6.
Deployment of dual stack device contribution to the same network implies the operation of both IPV4 and IPv6 over the same physical link. After all Ethernet and other layer 2 technologies support either IPv4 or IPv6 payload. Dual stack need router that supporting such link to be dual stacked as well.
IPv4/IPv6 Tunnelling Mechanisms
In order to reach the IPv6 Internet, an isolated host or network must use the existing IPv4 infrastructure to carry IPv6 packets. This is done using a technique known as tunnelling.
The term "tunnelling" refers to a means to encapsulate one version of IP in another so the packets can be sent over a backbone that does not support the encapsulated IP version. For example, when two isolated IPv6 networks need to communicate over an IPv4 network, dual-stack routers at the network edges can be used to set up a tunnel which encapsulates the IPv6 packets within IPv4, allowing the IPv6 systems to communicate without having to upgrade the IPv4 network infrastructure that exists between the networks.
A multiplicity of tunnelling technology has been developed to carry IPv4 over IPv6 and vice-versa. These technologies are known as configured and automatic. Configured tunnel are predefined, while automatic are created and torn down.
Configured Tunnels
The term "configured tunnels" is used when network administrators manually configure the tunnel within the endpoint routers at each end of the tunnel. Any changes to the network like renumbering must be must manually reflected on the tunnel endpoint. Tunnels result in additional IP header overhead since they encapsulate IPv6 packets within IPv4 (or vice versa).
IPv6 to IPv4 Automatic Tunneling Mechanism
Automatic tunneling refers to a tunnel configuration that does not need direct management. An Automatic IPv6 to IPv4 tunnel enables an isolated IPv6 domain to be connected over an IPv4 network and then to a remote IPv6 networks. Such a tunnel treats the IPv4 communications as a virtual no broadcast relation, so the IPv4 address surrounded in the IPv6 address is used to find the other end of the tunnel. The surrounded IPv4 address can easily be extracted and the whole IPv6 packet delivered over
the IPv4 network, encapsulated in an IPv4 packet. No configured tunnels are required to send packets among 6to4- capable IPv6 sites anywhere in IPv4 Internet.
Figure 2 shows the structure of the 6to4 address format. The value of the prefix field (FP) is 0x001, which the identifies global unicast address. The Top-Level Aggregation identifier field (TLA) is assigned by the IANA for the IPv6 to IPv4 mechanism. Hence, the IPv6 address prefix is 2002::/16 and the 32 bits after 2002::/16 represent the IPv4 address of the gateway host of the network in question. The 6to4 mechanism is the most commonly extensively used automatic tunneling technique. It includes a mechanism for assigning an IPv6 address prefix to a network node with a global IPv4 address.
(figure 2)
IPv6 Tunnel Broker
The IPv6 Tunnel Broker provides an automatic configuration service for IPv6 over IPv4 tunnels to users connected to the IPv4 Internet. IPv4 connectivity between the user and the service supplier is essential. The service operates as follows (Figure 3).
I. The user contacts Tunnel Broker and performs the registration procedure.
II. The user contacts Tunnel Broker again for authentication and provided that configuration information (IP address, operating system, IPv6 support software, etc.). IPv4/IPv6 Transition Mechanisms 113
III. Tunnel Broker configures the network side end-point, the DNS server and the user terminal.
IV. The tunnel is active and the user is connected to IPv6 networks.
Figure 3: 6over4 Address Link Layer Identifier
IPv4/IPv6 Translation Mechanism
It is essential when greater part of the internet has moved to IPv6 but some systems still use IPv4. If the sender is using IPv6 and the receiver is using IPv4 we can't use tunneling because the packet must be in IPv4 to be understood. Thus the header format must change totally trough the header translation. The header IPv6 is converted to IPv4 header so the receiver can understand.
Transition Requirements
The transition does not require any global coordination. Your sites and Internet service provider (ISP) can transition at their own pace. Moreover, an attempt has been made to reduce the number of dependencies during the transition. For example, the transition does not require that routers be upgraded to IPv6 prior to upgrading hosts.
Different sites have diverse constraints during the transition procedure. Moreover, in the beginning adopters of IPv6 are likely to have diverse concerns than production users of IPv6. RFC 1933 defines the transition equipment at present accessible. The foundation for transition is either the not have the IPv4 address space or the required use of new features in IPv6, or both. The IPv6 specification needs 100% compatibility for the existing protocols. Compatibility is also needed for existing applications during the transition.
To understand the transition approaches, you must know the following terms:
IPv4-only node - A host or router that runs only IPv4. An IPv4-only node will not operate with IPv6. The older base of IPv4 host and router that present before the transition begins are IPv4-only nodes.
IPv6/IPv4 node - A host or router that runs on both IPv4 and IPv6, which is also known as dual-stack.
IPv6-only node - A host or router that runs on IPv6 only.
IPv6 node - Any host or router that put into operation IPv6. IPv6/IPv4 and IPv6-only nodes are both IPv6 nodes.
IPv4 node - Any host or router that put into operation IPv4. IPv6/IPv4 and IPv4-only nodes are both IPv4 nodes.
6to4 router - Any boundary router that is configure with a 6to4 pseudo-interface on its IPv4 network connection. A 6to4 router provides as an endpoint of a 6to4 tunnel, over which the router onwards packets to other IPv6 site.
6to4 host - Any IPv6 host with a crossing point that is configured with a 6to4-unoriginal address.
Site - part of the private topology of the Internet that does not carry transfer traffic for anybody and everybody. The site can span a large geographic area. For example, the private network on a multinational corporation is one site.
Technical Details of IPv6
IP version 6 (IPv6) or IP next Generation (IPng) is a new version of the Internet Protocol, planned as the successor to IP version 4 (IPv4). The mainly changes from IPv4 to IPv6 are categorized into the following 8:
1: Longer addresses - 128 bits against 32 bits
Today we have 4 billion of IPv4 so do we really need to have more that this number? Yes because the population is estimated 9 billion in 2050 and the scope of IPv6 can be able to distribute more 300 trillion address so this must sufficient for the future generation to access the internet without any addressing problem.
IP v6 took into account that these users must have more than 1 networked machine. Even if the addresses are not allocated in good style, IP v6 can still distribute the IP in the demand without any precautionary measurement.
Nevertheless many users IP v6 can cope with, it is not possible that the world will switch to IP v6 overnight, which is why one of the biggest challenges for the creators of IP v6 was to make it backwards compatible with IP v4 before the transition of IPv4 routing and addressing to be complete.
2: Simplification of headers
Since there are only 7 fields compared to 13 in previous IP v4 - there is less operating cost while would be expected from headers for addresses of this size. This leads to faster processing by routers and better throughput. With some IPv4 header fields dropped or made optional, the cost of processing packets is reduced and the bandwidth rate is also imperfect. Yet there is another main difference which is there is no the "Checksum" field.
Another major difference is the absence of the "Checksum" field. With the beginning of data and transport layers have their own checksums, it was a misuse or and in an IP is now mostly redundant.
3: Better support for options
The aim of IPv6 is long-term protocol and it must eliminate all the problem and useless option and provide support for current useful options from IP v4.
Strict limits on the length of options, and greater flexibility for introducing new options in the future is provided for.
4: New extensions that support authentication and data integrity
If the connection need for security constraint; there is new extension that deals with it but in the case that is no need for security this extension is optional and won't slow down the throughput of the connection.
5: Flow labelling capability
This is a new ability to allow the labelling of packets belonging to particular traffic "flows" for which the sender requests special treatment, like non-default quality of service or "real-time" service.
6: Anycast address choice added and Multicast altered
The new "anycast" like a multicast address is used to send a packet to one node belonging to a specified group of nodes. However the packet of anycast is delivered to only one member of the anycast group, the nearest one. The scalability of multicast routing is enhanced by an addition of a "scope" field to multicast addresses.
7: Automatic Configuration
The automatic configuration that IPv6 provide will less overhead of complexity to the network administrator.
8: Backwards Compatibility
There is backwards compatibility and interoperability can be set in IPv4 within IPv6 address. Dual capable routers and hosts and IPv4, encapsulating IPv6 packets within IPv4 headers to carry them over segments of the end-to-end path where the routers have not yet been upgraded to IPv6.
IPv6 Challenges
If IPv6 is design to deal with the problem of IPv4 doesn't means that there is no challenges for IPv6. The following are most of the challenges of program perspective in the development of development of IPv6 transition plan
Maintaining interoperability and security during transition
Agencies will need to maintain network interoperability as they transition away from today's IPv4-only environment. In the early phase of transition, agencies are expected to move to an environment to put up native IPv6 and encapsulated IPv6, basically IPv4 network foremost to a ubiquitous dual-stack environment.
The uses of IPv4 reduce because of the transition agencies will operate in an environment largely as an IPv6 network. It is necessary that interoperability of hardware and software since agencies move forward with their IPv6 plans and interconnect their networks across dual environments. Since maintaining interoperability and protection for these types of growing environments is the highest priority, the transition time should be least as possible.
There are different kinds of combination of technical IPv6 transition strategies.
There are also a amount of transition mechanisms which are dual-stack, tunneling and translation. Which agencies can choose from with more rising from the technical community? Bear in mind that introducing of IPv6 in an enterprise scale will set up a number of challenges as well as scalability, integration, and security. In the near term, there is concern about creating vulnerabilities in existing IPv4 networks by deploying IPv6 and its transition mechanisms. This danger can be mitigated by improvement of an on the whole phased approach to IPv6 network transition which addresses end-to-end interoperability, performance, and security issues. Agencies possibly will think about controlling the use of IPv6 on IPv4
IPv4 networks that carry secret traffic until the networks carrying unclassified traffic have been successfully transitioned and tested. An incorporated and logical plan should be developed to allow IPv4 and IPv6 to operate on these networks using emerging IPv6 security products.
IPv6 Standards and Product Evolution
Nowadays, IPv6 technology is still rising and this development is possible to continue through the federal transition period. This is as estimated and is a normal evolution of the Internet standards. While the base set of IPv6 protocols are stable and established, and product implementations are rising, many of the principles supporting value-added IPv6 features are still evolving. Thus, agencies are encouraged to ensure the IPv6 capabilities being procured have a viable improve path.
Conclusion
It is a very big challenge that IPv6 hat is quickly and usually accepted by the large commercial user organizations of Internet. The transition danger is little and the technological viewpoint is often seen as the main factor for the decision.
In an perfect transition idea the pushing force would be the technical benefit and new features obtainable by IPv6, not any commonly decided schedule that is defensible by the termination of support for the older technology, the IPv4
One of the most important question remaind unanswer; is there aver a day that no need for IPv4 and can't be supported in the global internet fonctionality
References:
http://ezinearticles.com/?IPv4-Vs-IPv6-(Advantages-and-Disadvantages)&id=5160096
http://ntrg.cs.tcd.ie/undergrad/4ba2.02/ipv6/tech.html
http://whitepapers.technologyevaluation.com/pdf/6462/ipv4-to-ipv6-transition-strategies.pdf
http://ezinearticles.com/?IPv4-Vs-IPv6-(Advantages-and-Disadvantages)&id=5160096
http://www.eurojournals.com/ejsr_34_1_12.pdf
http://www.tascomm.fi/~jlv/ngtrans/
http://docs.sun.com/app/docs/doc/817-0573/transition-10?a=view
http://www.comscore.com/Press_Events/Press_Releases/2007/03/Worldwide_Internet_Growth
