Migration from IPv4 to IPv6 -The necessity and overview by leeonw

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									      Migration from IPv4 to IPv6 -The necessity and overview ASHOK.S




 Migration from IPv4 to IPv6-The
     necessity and overview




                  Ashok.S M.Tech.
E-mail id : ashok_vishnu2005@yahoo.com
    National Institute of Technology,
                           Trichy.




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                      Migration from IPv4 to IPv6 -The necessity and overview ASHOK.S


                                                 Abstract

Internet is the global network that consists of interconnection of millions of computers. The connections
between these computers are supplied by a list of rules which is called „Internet Protocol‟, shortly „IP‟. IP,
which is a member of TCP/IP protocol suit, is the protocol that describes how data is send across networks.
This protocol was initially designed to response limited specific requests. However, due to exponential
growth of Internet, the current version of IP has gradually become a bottleneck for the future of Internet. As
a result, transition to a new flexible and powerful protocol is unavoidable. This new protocol is called IP
version 6 (IPv6).

This report will be about the next generation Internet Protocol, IPv6. The purpose of this report is to inform
reader about current situation of Internet Protocol, necessity of transition to IPv6, features of IPv6 and
transition strategies for IPv6. Since IPv6 is a high approach of engineering study, therefore includes lots of
technical details, only key issues of IPv6 will be presented. This report will be beneficial for associates who
are interested in computer networking.




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Table of Contents
Abstract………………………………………………………………………………………………………...3

Introduction………………………………………………………………………………………………………4

Short History of IP………………………………………………………………………………………………4

Need for IPv6………………………………………………………………………………………………...….5

New IPv6 standard……………………………………………………………………………….6

Innovations in IPv6…………………………………………………………………………………6

Format of IP Address in IPv6……………………………………………………………………………….....8

Compatibility with IPv4…………………………………………………………………………..………….….9

Support for DNS……………………………………………………………………………………………......9

Deployment of IPv6………………………………………………………………………………………..…...9

Dual Stack Mechanism……………………………………………………………………………………………9

Tunneling Mechanism……………………………………………………………………………………….…..10
Protocol Translation Mechanism………………………………………………………………………….…..11


Deployment Cost in IPv6……………………………………………………………..………………………..12

Security concerns……………………………………………………………………………………..…..……13

Future of IPv6………………………………………………………………………………………………..….13

Conclusion……………………………………………………………………………………………………14

Reference……………………………………………………………………………………………….…....14




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Introduction

IPv6 is version 6 of the Internet Protocol. The Internet Protocol defines the way in which packets are
transmitted between machines using IP addresses. IPv6 is an upgrade to the IPv4 standard. There was an
IP version 5; it was used to identify an experimental streaming protocol for audio and video which is now
incorporated into and superseded by IPv6.

IP addresses, autonomous system identification numbers, and other such Internet resources are managed
centrally by an organization called IANA (Internet Assigned Numbers Authority), and the distribution of
those resources is delegated to five subordinate Regional Internet Registries (RIRs). APNIC, which is one
of these RIRs, is responsible for the Asia and Pacific region. RIRs allocate addresses in response to
requests from Internet service providers (ISPs) in each region as needed. The governments of Japan and
the European Union have mandated that, in the near future, network devices must support IPv6.

The Internet or network is described in terms of five layers. The lowermost layer is physical wiring such as
Ethernet cables. The second layer defines the data link which is used for communication over the physical
layer. The details of this layer are handled by Ethernet card. The third layer is the network or Internet layer.
This layer controls the way in which machines on the network are addressed. This layer is defined by the
Internet Protocol. The fourth layer is the transport layer. On the Internet there are two popular transports.
TCP is the Transmission Control Protocol and is used for common protocols including Email
(SMTP/POP/IMAP), the Web (HTTP), FTP, and others. Messages can be sent and received over the
connection. UDP is the User Datagram Protocol. It allows packets to be sent to remote machines without
the overhead of maintaining a connection. UDP is often used for simple protocols like DNS and for time
sensitive protocols. The fifth layer is the application layer. All of the familiar Internet protocols like HTTP,
SMTP, POP, IMAP, FTP, SSH, DNS, etc. are examples of this layer.

 Short history of IP

 The original specification for IP was published in 1981 as RFC 791 Internet Protocol. With a 32 bit
 address field, no one thought that the 4.3 billion possible addresses would get exhausted. At that time
 this was approximately equivalent to an IP address for everyone on the planet! The use of different
 classes of addresses with hierarchical subnets has meant that this once seemingly vast address pool
 has become severely depleted. As shown in Figure 1, depending on the class of network address, the
 number of hosts allowable could vary from 256 on a class C address, 65,536 for a class B address, or
 up to nearly 16.8 million for a class A address. Within each of these different classes, the addresses
 are further organized into subnets by using a subnet mask with a variable number of bits to indicate
 the subnet address and the host address.




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                                       Fig.1.1 IPv4 Address Format

 Class A addresses were typically allocated to government agencies and large organizations whereas
 class B addresses were allocated to large multinational companies and ISPs. This left the more limited
 Class C addresses to the rest of the population. As the Internet boom gathered pace in the mid 1990's,
 the demand for dial-up addresses in particular grew exponentially. Most ISPs had been allocated class B
 addresses and were limited in how they could create subnets to control and allocate their valuable
 address pool.

Need for IPv6
As mentioned earlier, IPv4 which is the current version in use is the only version that was deployed and has
not changed since RFC 791, which was published in 1981. However, it was designed only focusing on
small experimental network and today‟s growth of Internet was not considered. After two decades Internet
become a widely used popular communication tool. This popularity caused to reach structural limits of IP.

The scarcity of IPv4 address space also restricts the introduction of applications, innovative new services
that can be rolled out across both business and home networks. Without sufficient address space,
applications are forced to work in a very complex environment with mechanisms that provide local
addressing, such as IP address conversion, pooling and temporary allocation techniques.IPv4 addresses
are actually 32-bit numbers. For readability the numbers are split into four bytes (or octets) each of which is
rendered as a number from 0 to 255. The 32-bit address space of IPv4 contains about 4 billion addresses.
The original design of the Internet called for every device (computers, routers, game systems, iPhones)
hooked up to it to have a unique address the supply of available addresses is being depleted.
IPv6 is intended to replace the previous standard, IPv4, which only supports up to about 4 billion (4 × 109)
addresses, whereas IPv6 supports up to about 3.4 × 10 38 addresses. There are many different ways that
the limited number of IPv6 addresses have been stretched. Dial-up users are familiar with being assigned
an IP address out of a pool. DNS and cable users are typically assigned one IP address and a Network


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Address Translator (NAT) is used to route traffic to different ports on that IP address to machines assigned
local IP addresses.
IPv6 represents an opportunity to integrate new technologies right into the Internet Protocol, to expand the
address space to accommodate new kinds of Internet-enabled devices and applications, and to restore
some of the original ideas of IPv4 including the uniqueness of IP addresses and the embedding of routing
information in the IP addresses. In the future, there will be much greater demand for real-time transactions
as the Internet and intranets evolve from old-style data networks into complex transmission systems
carrying a vast wealth of data, entertainment and other services. IPv6 is designed to accommodate this
kind of global demand.

New IPv6 standard

The long term solution for the address depletion problem was to upgrade the underlying protocol to
handle more addresses. Originally known as the IP Next Generation Protocol (IPng), it was approved by
the IETF in 1994 as IP Version 6 or IPv6. The main goal of IPv6 was to increase the address field from
32 to 128 bits. It has been estimated that this is equivalent to one IP address for each molecule on the
planet! This should certainly be enough even with the way addresses are hierarchically assigned. In
addition to solving the address space depletion problem; IPv6 offers a number of other improvements
based on the commercial and consumer needs of the 21st century. These include:

       Redesign of the IP header to make it more efficient to process in routers.
       Larger address space and more hierarchical addressing options to improve routing
          efficiency.
       Automatic or DHCP based address configuration. Built-in end-to-end security
          using IPsec.
       End-to-end QoS support even for encrypted packets.
       Improved neighbor discovery protocol using ICMPv6 to replace ARP.
       Faster Traffic Quick transmission through efficient routing
       Trusted Connection - Authenticated connections for trusted computing.
       World-Ready Scalability - Capable of supporting and responding to future needs
       Advanced End-to-End Security - Better protection against address and port scanning attacks.


Innovations in IPv6
     Bigger address space
      The enlargement of the available address space will ease the pressure on the rapidly depleting
      IPv4 address pool and will slowly eliminate the need for NAT/DHCP devices to save and conserve
      addresses. As such IPv6 will open up the true potential of the Internet; any-to-any
      communication between any enabled devices.

     Faster routing and network auto-configuration
      Although the IPv6 address fields are four times the size of their IPv4 equivalents, the IPv6
      header is only twice the size of the IPv4 header. This has been achieved by removing redundant
      or unused fields and moving less used features to optional extension fields. The result is that

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   the IPv6 is much simpler to process and reduces the time taken to process IP headers in hosts
   and intermediate routers.

 End-to-end addressing and security
  The preponderance of NAT has broken one of the guardian principles of IP: that of secure end-
  to-end communication. This is due to the fact that NAT cannot handle encrypted messages
  with embedded address or port identifiers. In IPv4, the only way to implement secure
  communications such as IPsec-based VPNs has been to terminate the IPSec tunnels at a
  firewall and de-encrypt the packet before passing it in the clear to the host over the local
  network. IPv6 fixes this problem by using built-in IPsec to encrypt and secure packets on the
  host rather than at a firewall.

 More support for mobile devices
  As more 3G mobile networks are deployed, the opportunities to use mobile phones and PDAs
  as true data communication devices will increase. IPv6 includes built-in features to allow IP
  addresses to change as a mobile user moves between base stations which can reconfigure and
  reassign IP addresses.

 Improved multicast and streaming
  In IPv4, multicast was simulated by broadcasting to all devices in the neighborhood. This
  worked well on the LAN but could be a nightmare if implemented over a WAN. IPv6 provides
  multiple groups of multicast addresses so that multicast streams can be pinpointed to the
  required hosts and only those hosts.

 Jumbo-frames
  The maximum size of an IPv4 packet is limited to 64 Kbytes due to the 16 bit length field in
  the header. With IPv6, this restriction has been removed providing the associated TCP
  implementations can support it. This results in more efficient transmission of large data
  streams such as audio and video. What applications will benefit from IPv6?
   Although all applications will ultimately benefit from the release of pressure on the address
   space and the more efficient processing of IP packet headers, there are three application
   areas which in particular will benefit from IPv6 deployment.

 Mobile applications
  As more and more mobile devices become data capable, more demand will be placed on the
  IP address pool. It is estimated that mobile phones and PDAs will place the largest demand
  for new IP addresses. Each mobile device also requires multiple addresses as they move
  between cells and base stations. IPv6 provides significant improvements over IPv4 for
  managing the allocation of mobile addresses for these types of devices.

 Security applications
  IPv6 provides true end-to-end secure communication and will enable new security mechanisms
  to prevent spoofing, interception and tampering with IP packet data.


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     Multimedia applications
      Improved multicast methods mean that applications such as video and audio streaming, online
      gaming and Internet telephony will expand and prosper with IPv6. In particular, the end-to-end
      security capability in IPv6 will help boost the deployment of Voice over IP (VoIP) applications.



Format of IP Address in IPv6
The most visible change in the transition to IPv6 is the new format for IP addresses. IPv6 addresses are
128-bit rather than only 32-bit for IPv4 addresses. IPv6 addresses are written as a collection of eight 4-digit
hexadecimal numbers separated by colons. For example, an IPv6 address might appear as follows.
                   2001:0db8:0000:0000:0000:0000:1428:57ab
if an address contains one or more sections which consist entirely of zeroes (0000) then the address can
be abbreviated. Any section with four zeroes can be shortened to a single 0. The address above can be
abbreviated as follows.
                  2001:0db8:0:0:0:0:1428:57ab
In addition, a single run of zero sections can be shortened to simply::. The reader of the address is
expected to count the number of specified sections and expand :: into enough zero sections to fill out the
address. The address above can be abbreviated as follows.
                  2001:0db8::1428:57ab
The :: abbreviation can only be used once in any address. If an address has two non-contiguous runs of
zero sections then the longer of the two can be shortened. Also, it is technically valid to write an address
with 0000 in one section and simply 0 in another. This address is technically equivalent to the addresses
above even though it contains a mix of abbreviations.
                  2001:0db8:0000::0:1428:57ab
When an IPv6 address is specified in a URL it must be enclosed in square brackets. The following URL is
equivalent to http://localhost/ or http://127.0.0.1/.
                  http://[::1]/

Each IPv6 address breaks down into two parts. The first part is a prefix which specifies which service
provider owns a block of IP addresses. The second part is a suffix which identifies a specific machine in the
service provider's block of IP addresses. In the example address we've been using 2001:0db8 might
represent the service provider and 1428:571b represents a specific machine.
                 2001:0db8::1428:57ab
The length of the prefix will depend on how many addresses are assigned to the service provider. A service
provider with a six segment prefix has roughly as many internal addresses as are currently available in all
of the IPv4 address space! The suffix can either be provider dependent or may use a universal identifier
such as the 48-bit MAC address which uniquely identifies every Ethernet port and Airport card which has
been deployed.




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Compatibility with IPv4
A special prefix is used for backward compatibility with existing IPv4 addressed servers. ::ffff followed by
the IPv4 address using the usual notation represents an existing server. For example: ::ffff:209.173.53.180
represents the address of an server in an IPv6 compatible manner.

Support for DNS
The Domain Name System, most often known as simply DNS, is a core feature of the Internet. It is a
distributed database that handles the mapping between host names (domain names), which are more
convenient for humans, and the numerical IP address, which a computer can use directly.
When ordinary users use services on the Internet, the IP address is rarely specified directly. Instead, the
Destination to be accessed is specified by a text string called a domain name. The DNS is a distributed
database used to convert between domain names and IP addresses. It plays an important role in today‟s
Internet. The addition of the AAAA record resulted in the registration of IPv6 addresses in the root zone,
which is the basic database for the DNS worldwide. In other words, while help from IPv4 was previously
needed for DNS name resolution, name resolution is now possible even in an IPv6-only environment. The
JP DNS server that manages Japan‟s JP Domain has been capable of DNS look-up by IPv6
communication since 2004, and in the future, the DNS servers of all domains will be capable of domain
name lookup by IPv6 communication alone.

The DNS system has been expanded to return information about IPv6 addresses using a new AAAA
selector. IPv4 addresses are returned using the traditional A selector. Very few service providers have
transitioned to IPv6 addresses so there aren't many DNS servers currently serving IPv6 addresses.


Deployment of IPv6

Most network migrations are accomplished by shutting down the network, upgrading or replacing the
network devices to use the new protocol and then turning the network back on. But with the Internet this
is not possible .The huge investment in IPv4 based devices including routers and hosts means that
simply flipping the protocol version over is not a viable option. IPv6 migration will take years to
complete; during this migration, various methods have been recommended to handle the transition and
allow coexistence between the two protocol versions. IPv4 address must be assigned for every dual-stack
machine. Since IPv6 was developed precisely due to the scarcity of IPv4 addresses, this extra need of IPv4
address may be annoying. In order to achieve a smooth and healthy integration of IPv6 into existing
networks, IETF proposed variety of transition mechanisms. These mechanisms are come under three
general forms 1) dual-stacking, 2) tunneling and 3) translators

Dual Stack Mechanism
In order to participate in both an existing IPv4 and a newer IPv6 network, a host must support both
protocol stacks in its operating system. Most current operating systems support one of these

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methods. Dual-Stack devices are ones that maintain both IPv4 and IPv6 protocols. For
instance Microsoft Windows XP and Server 2003 support the dual stack approach while Sun Solaris,
HP True64 Unix and most Linux implementations support a dual layer integrated stack. This may be
accomplished by using a dual stack or a dual layer approach as shown in the below figure.




                                   Fig.1.2 Dual Stack Approach



 Tunneling Mechanism

 Currently there are a very small number of islands of IPv6 capable devices attached to the Internet.
 To communicate with each other, the IPv6 traffic is normally carried over the IPv4 network using
 tunnelling techniques. Tunneling mechanisms allows interconnection of separate IPv6 networks over
 IPv4 based services. The most common form of tunnelling is known as 6over4 in which IPv6 packets
 are encapsulated in IPv4 datagrams and sent across a tunnel. At the other end, the tunnel device
 de- encapsulates the IPv6 packet and delivers it to the local Ipv6 host as shown in Figure 1.3. For
 special cases such as campus environments and gaming communities, tunnelling techniques such as
 ISATAP and Teredo can also be used.




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                                    Fig.1.3 IPv6 over IPv4 Tunneling

The following tunnel mechanism will be used during transition period:

               IPv6 Manually Configured Tunnel
               IPv6 over IPv4 GRE Tunnel
               Automatic IPv4-Compatible Tunnel
               Automatic 6to4 Tunnel
               ISATAP Tunnel
               Teredo Tunnel

Protocol Translation Mechanism

Different from the cases dual-stacking and tunneling if there is no common protocol between peers, i.e. one
device is IPv4-only and other is IPv6-only device, protocol translators are used to provide connection
between these peers. However, it is advised to not use protocol translators when it is not obligatory
because some technologies such as IPSec cannot work with Network Address Translation-Protocol
Translators (NAT-PT). In-addition the following protocol translation mechanisms are under consideration:

               Network Address Translation-Protocol Translation (NAT-PT)
               Bump-in-the-Stack (BIS)
               Multicast Translator Proxying
               Transport Relay Translator (TRT)
               Bump-in-the-API (BIA)
               SOCKS-Based Gateway




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Deployment Cost in IPv6
Technology costs
(1) Planning. Agencies will have to plan how they will phase IPv6 into their operations. It may be safely
assumed that all equipment purchased after a certain date will be capable of running under either IPv4 or
IPv6, with automatic sensing as to which protocol is in use. Changing operations may be more complex if
advantage is to be taken of IPv6 features. Plans for retrofitting old equipment, if necessary, must also be
drawn up.
(2) Transition. This will be most critical in those areas where operations are going to change as a result of
new IPv6 capabilities. Where there is no operational change, use of hardware which can operate under
either protocol should eliminate most transition problems, with older IPv4-only equipment eventually
becoming obsolete for other reasons and eliminated. It can safely be assumed that equipment
manufacturers such as Cisco will deploy the software needed to handle the overlap period, and ensure
smooth transition at that level. In general, equipment providers and service providers are well prepared to
handle a possible IPv6 transition because it is their business to adopt new standards as quickly as
possible.
(3) Implementation. It will be necessary to replace all existing IPv4 hardware with new hardware that can
handle both IPv4 and IPv6, or IPv6 only. As this includes nearly every PC in existence, millions of switches
and routers, and many mobile devices, that will not be inexpensive. However, the cost issue is mitigated by
the fact that transition to IPv6 is expected to take many years, and most of today‟s equipment will have
been scrapped long before IPv6 takes over and IPv4 is permanently retired.
(4) Operations. New operational capabilities taking advantage of IPv6 capabilities may require more
microprocessor-based devices, and thus more trained staff to operate and maintain them. If operations
change, then training for all staff in new procedures will become necessary. If applications programs need
to be modified or new ones written, costs could become high.
Human factors costs

These costs tend to be underestimated because people tend to underestimate the difficulty and time
associated with changes in business practices.In general, it can be assumed that, in addition to transition
costs, there will be a period of adjustment to new technology during which productivity may actually
decrease. Some workers may never feel comfortable with it. IPv6 is fortunately buried far down in the
technology infrastructure, so these problems will most likely be less than in other cases. These costs have
to be estimated on a case-by-case basis, and will be greatest when there are large operational changes in
an office.




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Security concerns
          Unauthorized computers communicating on private networks. With an access to the
            network, it is easy for any computer to obtain a valid IPv6 address configuration and begin
            communicating. To avoid this unauthorized communication, authorization for automatically
           assigned addresses and configurations is required. Using IEEE 802.1X-based
            authentication at the link layer, a computer can be stopped from sending any network
            traffic until it is authenticated itself to a switch or wireless access point.

          Security of IP Packets. Tampering of IP packets, spoofing, and passive capturing pose
            threats to the protection of IP packets. Using cryptographic security service such as IPsec
           defined in RFCs 2401-2409 for both IPv4 and IPv6 traffic, IP packets can be transmitted
            safely over the network.

          Host Scans and attacks. Malware such as viruses and worms scan or attack hosts. An
            attacker can scan IP address of the host and use the services and resources of the host.
           Using the default behavior of IPv6 for Windows Vista to randomly derive the 64-bit
            interface ID and the Windows Firewall or any host based firewall, scans and attacks on
            hosts can be avoided.

          Unwanted traffic. Deploying edge firewalls or proxies and intrusion detection systems
            (IDSs), an attacker's traffic cannot penetrate in to the private network. As all of these
            security devices are currently not IPv6-capable, there are additional security risks for IPv6
          
            traffic.


Future of IPv6

The R&D Teams involved in development of IPv6 aim to bring the following innovations to reality. The
features include,

       Mobile-phone (with video data), xDSL & FTTH
       Broadband video-data stream on IPv6 network
       High speed forwarding and QoS, like IPv4 or more!
       High performance Security
       High speed load balancing for large-scale “Internet Data Center”.
       “Always On” Internet traffic is manageable.
       Protection from Denial of Service attacks.
       Interactive Television and Video games over the Internet.




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Conclusion

The main concepts of IPv6, its features and deployment strategies have been discussed. The solution to
limited address space of IPv4 is provided by IPv6. Most of these benefits are related to 128-bit hierarchic
addressing and its astronomically large address space. IPv6 is an evolution of IP but not revolution,
transition to IPv6 will continue over a period of time. Any company planning to implement IPv6 in their
network should consider that even though IPv6 mostly took shape, some features still continue changing. In
addition, such companies should benefit from experiments of other organizations or companies that are
completed their transition to IPv6.




Reference

     IPv6 Forums

     IPv6 Task Force




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