Over the past five decades, the Internet has grown, changed a lot and, now used as a business platform and has become a central part of social life. With the increasing number of users, providers, services and with the advent of this ubiquitous era, Internet is facing some challenges like scalability, adaptive routing, ad-hoc formation. The main issues lying with the Internet of today are:
Interoperability and trust framework for service integration, authentication, privacy and security.
How can the Internet handle the intelligent devices that can sense and react to physical objects.
What actions are needed to facilitate the exchange of user-generated content/services
What standards are needed, in particular meta data standards, to ensure searchability and interoperability.
In such a scenario, the existing Ipv4 protocol seems to be inadequate to address these problems and Ipv6, although introduced and proposed in 1994, emerges as a natural replacement now-a-days.The current generation of IP, version 4, (IPV4), is roughly 20 years old. Since its inception in the 80's, it has supported the Internet's rapid growth during that time. It has been proven to be robust, easily implemented and interoperable.The current Internet has grown much bigger than was anticipated. There are several problems such as impending exhaustion of the IPv4 address space, configuration and complexities and poor security at the IP level.
To overcome these concerns, in the early 90's, IETF (Internet Engineering Task Force (IETF), began developing a new IP protocol namely IPv6 (other name, Next Generation IP, IPng). It will use a 128-bit address space. In the other hand, it would support unique addresses well beyond the trillions. It can support 340, 282, 366, 920, 938, 463, 374, 607, 431, 768, 211, 456 unique addresses! It will not only eliminate the shortcomings of IPv4, but also unlock new features and services.
1. Introduction
The future of the Internet is its ability to scale to connect billions of people and devices. With the advancement of technology,devices like PDAs, mobiles, pagers are connected to the Internet. And advancing to the 5G Ubiquitous era, where we are going to have '4As' model - anytime, anywhere, any device,
Always connected and can be extended further to '7As' - anytime, anywhere, any device, always connected, affordable, all security, any information services. Seamless hand-off and roaming, no service interruption, omnipresence, persistency, context awareness are going to be the key issues and for that identifying each and every devices uniquely has become mandatory. With Ipv6 having a pool of very large address space, it is possible to
Refer to each computing device with its own unique address.
Automatic address configuration and reconfiguration i.e. servers can re-number network addresses without accessing all clients. Thus enabling the mobile clients to move about the network.
However, for next couple of years the Internet will be made up of both IPv4 and Ipv6 hosts. For isolated IPv6 devices to communicate with one another, Ipv6 connections over IPv4 network can be set up. This is known as Tunneling. Tunnel can be configured manually and data can be sent using the tunnel as an interface. Again for Ipv6-only devices to communicate with Ipv4-only devices a backward compatibility is needed. To implement these types of challenges, several socket interfaces have been defined and different techniques like Tunneling, Dual-stack,and Backward Address Translation have been defined.
2. Future Internet:
The three main features of future Internet are going to be mobility, quality of services and security. Mobility management, seamless connectivity, auto-configuration are expected issues to be competent with the proposed adhoc 5G world. Again, with the advent of mobile telephony and IPTV in a ubiquitous converged Internet, the need for Quality of Service (QoS) has also been increased.
The parameters for improvement of QoS are:
End-to-end multi path congestion control.
Selective flow-label admission control
Flow-aware networking approach
Adaptive traffic dependent routing.
The future Internet will not only be mandated by technical challenges but there are governance, societal and environmental challenges also. The challenges are depicted pictorially in Figure below
www.networkworld.com/.../graphics/17fig11.jpg
Ipv4 and Ipv6
Ipv4
Internet Protocol version 4 is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. IPv4 is the dominant network layer protocol on the Internet and apart from IPv6 it is the only protocol used on the Internet.It is described in IETF RFC 791 (September 1981) which made obsolete RFC 760 (January 1980). The United States Department of Defense also standardized it as MIL-STD-1777.
IPv4 is a data-oriented protocol to be used on a packet switched internetwork (e.g., Ethernet). It is a best effort protocol in that it does not guarantee delivery. It does not make any guarantees on the correctness of the data; It may result in duplicated packets and/or packets out-of-order. These aspects are addressed by an upper layer protocol (e.g., TCP, and partly by UDP). The entire purpose of IP is to provide unique global computer addressing to ensure that two computers communicating over the Internet can uniquely identify one another.
3.1.1 Limitations of IPv4
Most of today's internet uses IPv4, which is now nearly twenty years old. IPv4 was remarkably but in spite of that it is beginning to have problems. Most importantly, there is a growing shortage of IPv4 addresses, which are needed by all new machines added to the Internet.
The limited address range forces organizations to use Network Address Translation (NAT) firewalls to map multiple private addresses to a single public IP address. NATs does not support standards-based network-layer security and also creates complicated barriers to VoIP, and other services.
The routing tables of Internet backbone routers are becoming larger. A separate routing table entry is needed for each network resulting in a large number of routing table entries.
Security was also an issue for IPv4. Although there are lots of ways of encrypting IPv4 traffic, such as using the IPSec protocol, but unfortunately all of the IPv4 encryption methods are proprietary and no real standard encryption methods exist.
3.2 Ipv6
The IPv6 header has a new header format that is designed to minimize header overhead. This optimization is achieved by moving both non-essential fields and optional fields to extension headers that appear after the IPv6 header. A host or router must use an implementation of both IPv4 and IPv6 to recognize and process both header formats. The IPv6 header is only twice as large as the IPv4 header, even though IPv6 addresses are four times as large as IPv4 addresses.
IPv6 features a larger address space than that of IPv4. IPv6 has 128-bit (16 byte) source and destination IP addresses. Although 128 bits can express over 3.4Ã-1038 possible combination's, the large address space of IPv6 has been designed for multiple levels of subnetting and address allocation from the Internet backbone to the individual subnets within an organization.
Multicast, the ability to send a single packet to multiple destinations, is part of the base specification in IPv6. This is unlike IPv4, where it is optional (but usually implemented).
IPv6 offers a higher level of built-in security, and it has been specifically designed with mobile devices in mind. The mobility comes in the form of Mobile IP, which allows roaming between different networks without losing an established IP address. Unlike mobile IPv4, Mobile IPv6 (MIPv6) avoids triangular routing and is therefore as efficient as normal IPv6.
IPv6 can easily be extended by adding extension headers after the IPv6 header. Unlike options in the IPv4 header, which can support only 40 bytes of options, the size of IPv6 extension headers is constrained only by the size of the IPv6 packet.
IPv6 also includes standardized support for QoS. The QoS implementation is set up so that routers can identify packets belonging to an individual QoS flow. Furthermore, QoS instructions are included in the IPv6 packet header. This means that the packet body can be encrypted, but QoS will still function because the header portion containing the QoS instructions is not encrypted. This will make it possible to send streaming audio and video over the Internet with IPSec encryption, but in a manner that guarantees adequate bandwidth for real-time playback.
3.2.1. CURRENT STATE OF DEPLOYMENT OF IPv6:-
The Internet Protocol version 6 (IPv6), a redesigned version of IPv4, aims to overcome the limitations of its predecessor and address the challenges of the future networks. IPv6 corrects or optimizes some features of the IPv4 protocol. IPv6 address space is, relative to IPv4, abundant for the foreseeable future. With IPv6 having been designed, implemented, tested and (in limited amounts) deployed over the last 10 years. The core IPv6 standards are stable, to the extent that they can be deployed today. This status is reflected by the fact that the IPv6 Working Group in the IETF has been closed and replaced with one entitled '6man' which is responsible for the maintenance, upkeep, and advancement of the core IPv6 protocol specifications.
Administrators must consider addressing and node configuration deployment strategies that will yield the appropriate level of automation, flexibility, and control.Ipv6 deployments will typically utilize one or more address types including unicast, multicast, and any cast. Address assignment and node configuration choices include static, stateful DHCPv6, stateless DHCPv6, and stateless auto-configuration must also promote error-free, efficient deployments. Advanced implementation of converged, next generation services demand evaluation and dynamic policy to capitalize on the benefits that DHCPv6 offers, centralized management is also essential.
DHCPv6 management should provide the ability to configure a server for stateful, stateless, or both modes. Simultaneously, while preventing the inadvertent use of overlapping address pools and duplicate assignments properly managed DHCPv6 implementation can also be used to determine the accurate state of address. Utilization, as well as manage relationships among DHCPv6 servers.
3.3. New Features in Ipv6:
Multi cast :-
The ability to send a single packet to multiple destinations. When even the smallest IPv6 global routing prefix is assigned to an organization, the organization is also assigned the use of 4.2 billion globally routable source-specific IPv6 multicast groups to assign for inner-domain or cross-domain multicast applications.
Security:-
IPv6 incorporates Internet Protocol security (IPsec), which provides for authentication, encryption, and compression of IP traffic. IPsec support is mandatory in IPv6; this is unlike IPv4, it is optional.
Mobility:-
IPv6, mobile access of the Internet becomes simplified to a great extent, as it incorporates a specific protocol, called Mobile IP to support mobility. In an IPv6 environment, there is support for roaming between different networks.
Qos:-
IPV6 brings quality of service that is required for several new applications such as IP,telephony, video/audio, interactive games or ecommerce. Whereas IPv4 is a best effort service, IPv6 ensures QoS, a set of service requirements to deliver performance guarantee while transporting traffic over the network
3.4 Differences between Ipv4 & Ipv6:
IPv4:-
* Source and destination addresses are 32 bits (4 bytes) in length.
* IPSec support is optional.
* IPv4 header does not identify packet flow for QoS handling by routers.
* Both routers and the sending host fragment packets.
* Header includes a checksum.
* Header includes options.
* Address Resolution Protocol (ARP) uses broadcast ARP Request frames to resolve an IP address to a link-layer address.
* Internet Group Management Protocol (IGMP) manages membership in local subnet groups.
* ICMP Router Discovery is used to determine the IPv4 address of the best default gateway, and it is optional.
* Broadcast addresses are used to send traffic to all nodes on a subnet.
* Must be configured either manually or through DHC.
* Uses host address (A) resource records in Domain Name System (DNS) to map host names to IPv4 addresses.
* Uses pointer (PTR) resource records in the IN-ADDR.ARPA DNS domain to map IPv4 addresses to host names.
* Must support a 576-byte packet size (possibly fragmented).
IPv6:-
* Source and destination addresses are 128 bits (16 bytes) in length.
* IPSec support is required.
* IPv6 header contains Flow Label field, which identifies packet flow for QoS handling by router.
* Only the sending host fragments packets; routers do not.
* Header does not include a checksum.
* All optional data is moved to IPv6 extension headers.
* Multicast Neighbor Solicitation messages resolve IP addresses to link-layer addresses.
* Multicast Listener Discovery (MLD) messages manage membership in local subnet groups.
* ICMPv6 Router Solicitation and Router Advertisement messages are used to determine the IP address of the best default gateway, and they are required.
* IPv6 uses a link-local scope all-nodes multicast address.
* Does not require manual configuration or DHCP.
* Uses host address (AAAA) resource records in DNS to map host names to IPv6 addresses.
* Uses pointer (PTR) resource records in the IP6.ARPA DNS domain to map IPv6 addresses to host names.
* Must support a 1280-byte packet size (without fragmentation).
3.5 Advantages of Ipv6 over Ipv4
Larger address space
Support for mobile devices
Improved address management
Built-in security with end-to end IP Sec
Enables more levels of hierarchy for route aggregation
Makes it possible to upgrade functionality as needed, e.g., multicasting and QoS
On the IPv6 platform, billions of new devices such as cell phones, PDA's, appliances and even cars can be IPv6 enabled
The Internet can extend its reach to billions of new users in densely populated regions of the world
The protocol makes "always on" access technologies like xDSL, Cable or Ethernet connectivity easy to implement.
4. Ipv6: A solution to Next-Generation Internet:
The major difficulty to reform the Internet to cope up with the Next-generation challenges is its size. The Internet has grown to become so large that it has been extremely hard to deploy it with a newer technology. That is why it is being done with the following 2
techniques:
(i) By Incremental Evolution: To develop the Internet architecture by adding (or removing, if required) functionality without changing the prevailing design principles and model. In Ipv6 specific scenario, this is related to the Dual Stack Architecture.
(ii) By Applying Virtualization: To develop logically independent networks built onacommon physical infrastructure to deploy new network functionalities and protocols. IP Tunneling and Address Translation comes under this type of implementation.
Before discussing the Dual Stack, Tunneling, Translation techniques, let's tabulate the specific IPv6 Header features for which it is being seen as future-generation Internet protocol:
Scalability Management with large address space of 2^128.
Supporting Seamless Handover in a heterogeneous network with MAP (Mobility Anchor Point) protocol and neighbor discovery support.
More data integrity and authentication with IPSECv6 feature.
Improved QoS by assigning specific value in Traffic Class and Flow Label field.
4.1 Dual Stack:
Dual stack is one of the ways to introduce IPv6 to a network. Using this method a host or a router is equipped with both IPv4 and IPv6 protocol stacks in the operating system. Each node is called an "IPv4/IPv6 node" and is configured with both IPv4 and IPv6 addresses. It can therefore send and receive datagram belonging to both protocols and thus can communicate with every node in the IPv4 and IPv6 network.
Dual-Stack
Node
Ipv4/Ipv6 node
Ipv4 Ipv6 Network Bus
Ipv4 Ipv6
Ipv6
Ipv4
Dual-Stack
Node
Ipv4-only
Node
Ipv6-only
Node
Figure 2 : IPv6 Dual Stack Protocol
The main challenge in the implementation of dual-stack mechanism is the interaction of two protocols and how this interaction is managed. Theoretically an Interface configured for dual-stack operation resides at the boundary between an Ipv4 network and an IPv6 network. Figure 3 explains how a data packet is managed internally by a dual-stack IPv4/Ipv6 node:
Suppose, an IPv6 host transmits a service request packet. The source and destination addresses use IPv6 format.
IPv6 interface receives the packet
The IPv6 packet is internally encapsulated inside an IPv4 packet in the Dual- Stack Node.
IPv4 interface transmits the packet using IPV4 format.
IPv6 Interface
Ipv4 Intherface 1 2 3 4
------> ---ïƒ ------ïƒ --------ïƒ
IPv4/IPv6 Node
IPv6 Host IPv4 Host
Figure 3 : Dual Stack Transition Mechanism
The advantage of Dual Stack mechanism is that it increases scalability. To say about the disadvantages,for security issues this mechanism can use IPv4 IPSEC only, it can not use IPSEC feature of IPv6 protocol.
4.2 IP Tunneling:
Tunnels are used to transport Ipv6 packets over an existing IPv4 network infrastructure. The tunnels are created between dual stack nodes at the edge of IPv4 network. Tunnels are of mainly 2 types: (1) Router-to-router Tunneling and (2) Router-to-host Tunneling.
Figure 4 : IP Tunneling Mechanism
Figure describes the basic principle of IP Tunneling. Suppose networks A and C are Ipv6 only network islands connected by IPv4 only network B. Routers R1 and R2 reside at the edge of networks A and C and are dual-stack nodes. They are connected by a permanently configured IPv4 Tunnel across network B. An IPv6 packet from Host1 to Host2 travels through the following steps:
The Ipv6 packet travels from Host1 to R1 through Network A.
At R1, the packet is encapsulated with an IPv4 Header. The source address and destination address become the IPv4 address of R1 and R2.
At R2, the encapsulating IPv4 Header is discarded and the original IPv6 packet is forwarded across network C to H2. The tunnel between R1 and R2 is hence called an IPv6 over IPv4 tunnel.
In case of Router-to-host routing, the router is replaced by a Dual-stack node at one end. The advantage of Tunneling over Dualstack mechanism is that Due to encapsulation IPv6 header in IPv4 header, it can use IPSEC feature of IPv6 protocol. However, there are some disadvantages like manual-configuration of Tunnel entry and exit point during each time of configuration, transmission overhead due to encapsulation of IPv6 packet in IPv4 header.
4.3 Address Translation:
It is a mechanism to translate a Ipv4 datagram header into a semantically equivalent Ipv6 datagram or vice versa. In this protocol, a translator located in the network layer in the protocol stack ,called "Header Translator" translates IPv4 datagram to IPv6 datagram. The difference with the previous two protocols is unlike Dual Stack, Tunneling protocol, it changes the content of the IP Header. The result is a new semantically equivalent header but not equal. There are different protocols to implement Address Translation like: (i) Stateless IP/ICMP Translation Algorithm (SIIT) [RFC 2765], (ii) Bump In the Stack (BIS) Algorithm [RFC 2767], (iii) Network Address Translation with Protocol Translation (NAT-PT) [RFC 2766], (iv) Bump in the API (BIA) [RFC3338] Algorithm etc. The protocol is useful during initial stages of IPv4 transition to Ipv6 Transition, especially when IPv4 application remain unmodified within IPv6 domain. The disadvantage is that its performane is always limited to translation capabilities. So it can not send/receive IPv4 packets to/from the network. As a result, IPv4 only communication also need an address translation.
5.Conclusion:
As discussed in the previous sections, Ipv6 remains a great solution to face the challenges of future Internet.
Total of 1922 IPV6 enabled products by different Vendors are identified by the IETF IPV6 and IPV6 maintenance Working Groups.
Products like MX 1 HD 1080p IP Set Top Box by Matrix Stream Technologies, RBM IP Set Top Box by Right Brain Media provide IPV6 support for Home Entertainment.
DI-524D Router from D-Link supports IPV4-IPV6 dual stack V6 to V4 tunnel function.
Network Cameras from companies like Canon, Panasonic, Sanyo etc support IPV6.
Internet Security applications from companies like Symantec, Bit Defender, Kaspersky support IPV6..
IPv6 is already widely deployed in Japan. IPv6 was trailed as a way of monitoring traffic by installing detectors in cars
European Commission as well as the Taiwanese and Korean governments have mandated the move and other Asian countries are working towards it
Google has launched a public IPv6 web interface to its popular search engine at the URL http://ipv6.google.com
Additional standards for Stateful autoconfiguration (DHCPv6), IPSec key exchange (IKEv2), Secure Neighbor Discovery (SEND), and IPv6 over emerging link layers (802.15, WiMAX, etc) are being tested and deployed in new IT infrastructure. The integration of IPv6 into enterprise applications, network management, and security infrastructure is already in progress by governmental initiatives in Asia and the U.S. The U.S. Government, for one, has issued a mandate that the network backbones of all federal agencies must deploy IPv6 by 2008. As things stand, the IPv6 Forum projects the worldwide Internet penetration to reach 25% by 2010, 35% by 2015 and 50% by 2020. By the year 2010, according to the Ipv6 Forum, "IPv6 will become a dominant protocol and the New Internet will become commodity for everyone and everything."
