Internet Protocol Version 6
Internet Protocol Version 6 Arne Schipper [email protected] Reykjavı́k University ABSTRACT This paper describes IPv6, the new Version of the Internet protocol. Currently IPv4 is the standard for the Internet, there are just some few research projects and encapsulated nets that make use of the new version of the Internet Protocol. The main differences and advantages in comparison to IPv4 will be addressed, clarified with examples. Some outlook will be given, considering when and maybe even if the new version will be remarkable in use. Keywords IPv4, IPv6, Internet Protocol, IPng 1. INTRODUCTION The Internet (abbr. Interconnected Networks) is a worldwide network of independent networks. The main purpose is to provide facilities for communication and information exchange. Every computer of the Internet can basically communicate with every other. This is made available by defined protocols. Very often people use the world wide web (www) synonymic for the Internet, though this is just a part of it. The Internet emerged from the ARPANET, with was founded by the Advanced Research Project Agency of the US Department of Defence in 1969. This research agency made first attempts with packet switched networks, to reduce the error-proneness and improve the workload of normal circuit switched networks. It took long time to establish the Internet as the institution as we know today. Many different protocols, institutions and applications were created and used. First, the network was used to interconnect American universities researching for military purposes. In 1983, when much non military information flew through the ARPANET, the ARPANET became separated into a scientific ARPANET and a military MILNET, connected by gateways. One year earlier, the decision was made to switch the ARPANET to TCP/IP, to allow easy connections to the CSNET, another research network. In 1990 the ARPANET was switched off, the net access moved more and more to commercial providers and universities were given funds to receive net access. Since 1983 the Internet Protocol suite became the only protocol used for the Internet. Many different, sometime proprietary solutions tried to gain distribution, but alltogether failed. So today, the Internet Protocol (IPv4) is, apart from IPv6, the only standard used throughout the Internet. In this paper there will be first provided a explanation of the currently used version, the IPv4. The general architecture will be covered and it will be considered inside the Internet protocol stack. Then the main drawbacks of the IPv4 will be listed and discussed. Another chapter will explain, how with these drawback was coped to maintain the working of the Internet. Different extensions for IPv4 will be covered. The main chapter will introduce IPv6, its specification and how all the drawbacks of the previous version were faced. In the last chapter some outlook will be given how and when the Internet Protocol version 6 will be introduced. 2. INTERNET PROTOCOL VERSION 4 2.1 The IP in the Internet protocol stack The Internet Protocol is just one of the protocols providing the functionality of the Internet. All the protocols used to operate the Internet can be described in a protocol stack, which consists of different layers for each sort of service. This structure is similar from the ISO/OSI reference model, but the actual implementation is slightly different. The Internet mainly consists of four layers, as described in figure 1 Figure 1: Internet Protocol stack  The lowest layer (we do not look an the physical layer like wire, glass fibre or Carrier pigeon ) is called data link layer. Mostly Ethernet is used for the implementation of that layer, but it is also possible to utilise Token ring, ISDN, 802.11 WiFi, PPP, etc. The main purpose of that layer is to pass packets from the network layer to the desired destination host within the same network. No routing is provided by this layer, neither are any guaranties given that the data will reach its destination. The process can be controlled in a network interface card firmware, or by software drivers. The next layer, called network layer, makes use of the Internet Protocol, currently mostly IPv4. The main task of this layer and the Internet Protocol is to move so called IPpackets from a source to a destination. Addressing is done using IP-addresses. The main benefit of that protocol is that it can operate over the physical borders of a single network using routers. The Internet Protocol is that protocol which defines the Internet as a group of loosely connected computers, as it defines a end-to-end protocol. This protocol is rather simple, that is also a reason why it became such widespread, but another reason for lacking of certain services. These services, like guarantied in order delivery, are provided by the next layer, the transport layer. A protocol providing these services is the Transport Control Protocol (TCP), which is in wide use in the Internet, resulting in the term TCP/IP protocol suite, which makes up the Internet. Another famous protocol on that layer is User Datagram Protocol (UDP), which is much easier and faster, as it does not guaranty delivery like TCP. Using all these techniques, the application layer is on top of the stack. Here are the famous protocols like HTTP, SMTP, SSH, BitTorrent, telnet, which made the Internet to what it is now. 2.2 2.2.1 IPv4 in detail History When the Internet Protocol was designed, the circumstances regarding the number of hosts and the net topology were quite different from nowadays. In the very beginning in 1969, just 4 computers were connected to each other. This number grew only moderately during the next few years , which can be seen in figure2. So designing a protocol in that times was quite different from what would have happened today, or even a decade ago. A main issue then was to reduce the amount of memory space needed. When designing IPv4  the authors thought that 232 addresses should be sufficient. Some other features implemented in this first version were never or hardly used, whereas some other important features were missing and had to be incorporated into the existing structures. 2.2.2 Figure 2: Number of hosts connected  Figure 3: Formats of classed IP addressing  Thus resulted in a relatively small number of so called class A subnets (namely 124), but each net could contain ≈ 16.7 M hosts. In the 16,384 class B nets it is possible to have 65,534 hosts, whereas in the 2,097,152 class C nets it is possibly to work with 254 hosts. Due to this architecture, there were problems in assigning new IP addresses to new hosts, but this will be discussed further in Chapter 2.3.1. 2.2.4 Address 127.0.0.0/8 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 220.127.116.11/4 255.255.255.255 Address format IPv4 uses 32 bit addresses, which leads to a theoretical possible number of 232 ≈ 4.3 Mia addresses. Addresses are normally displayed in dot-decimal notation, that means in 4 decimal numbers of 8 bits, e.g. 18.104.22.168. Other notations are hexadecimal and octal representations. 2.2.3 Address allocation Originally, the IP address was divided into two parts: A network part and a host part. Special address ranges There are several address ranges reserved for special purposes. These reservations were not there from the beginning of the Internet Protocol. The most popular address ranges are listed below in table 1, note that they were not reserved from the beginning, but were slowly added to the IPv4. They were summed up in several RFC, as for example in RFC 1700 . Use loopback device private class A network private class B network private class C network multicasts broadcast Table 1: Some IP address ranges 2.2.5 IP packet format IP packets consist of a header and the payload data. The actual interesting of an IP packet is the header, see figure 4. It contains several fields with protocol information. The most important fields are the source and destination address, both 32 bits fields, as explained above. The other fields hold information about the version (4 for IPv4), whole length of the header, type of service, checksums and more information like TTL, time-to-live. The type of service (TOS) field was intended to be used for precedence handling of certain IP packets, but that was very seldom implemented. The field total length indicates the total length of the whole IP packet, that means header and payload data. As this is a 16 bit field, the maximun length of an IP packet is limited to 64 kB. This is hardly used, as most communication goes over ethernet, and and fragmenting is slow, the size of an IP packet is adjusted to the payload size of an ethernet frame, often called MTU (maximum transfer unit), which is 1500 bytes. It is possible, to use extra option fields of the IP header, each of a size of 32 bit, this must be announced in the IHL field. Figure 5: Number of hosts in the DNS  With the initial design of the Internet Protocol, namely the differentiation of the address in a host a network part, it was quite easy for the big Internet routers to route the IP packets to the desired networks. But with the changes made to the protocol, see chapter 2.4, another problem arose. The main routing tables were growing bigger and bigger. The router needed to hold the information about the next router for every destination address in memory, because of speed concerns. With the growth of the routing tables that became a remarkable problem. With almost every new host in the Internet, new entries had to been make. This resulted in tables sizes as shown in figure 6. In the tentative draft for the routing tables the designer chose a table size of 10.000 , which was to be exceeded in January 1993 and a big problem had top be solved. Figure 4: IPv4 header  Directly after the header begins the payload section. Depending on the header size, and assuming a MTU of 1500 bytes, we can use up to 1480 bytes for data, that is a ratio of 98.6 %. If a TCP datagram is sent, the the TCP header and the TCP payload data will be inside this IP payload frame. This actually leads to a lower ratio of payload data. 2.3 Drawbacks of IPv4 During the short explanation of IPv4 some drawback were already mentioned. To understand why a new Internet Protocol is necessary, it is importend to draw out more disadvantages and to discuss them. 2.3.1 IP address depletion As mentioned before, it is theoretically possibly to assign ≈ 4.3 milliard IP addresses to host. Due to very unrestricted allocation of IP addresses, that is for example be assigning a complete class A network with 16.7 million addresses, there were nor many addresses left. There were different predictions of running out of class B addresses around the year 1994 . As big parts of the subnets were not used, estimations were predicting only 240 million useable IP addresses , though this should be higher today. Nevertheless this number is today be far exceeded, as can be seen in figure 5. 2.3.2 Growing routing tables Figure 6: IPv4 Internet route table entry trend  2.3.3 Complicated header format The header was initially designed to be flexible and extendable. There the decision was made to allow additional header fields, as described above. With other fields like header length and checksum, there was little room for efficient (hardware) routing, as the header had to be examined exactly: it was necessary to analyse the optional fields and to build the checksums. 2.3.4 Security problems With IPv4 it was not possible to establish secure connections. Securing the channel had to be done by extensions or the upper layers, like IPSec or SSH. Therefore the communication partner you want to talk to also needed the same protocols, a condition which was not always met. 2.3.5 Bandwith reservation problems Though there is a field in the IPv4 header (ToS) which should be used to specify the priority of a package, it was hardly used. Some research groups suggest to use this field with techniques like Differentiated Services , but this is not quite sophisticated yet and just a workaround applied to the given structure of IPv4. 2.3.6 No multicast The initial design of IPv4 did not make any arrangements for multicast. That became a problem when huge amounts of data had to be transmitted to a group of hosts, e.g. video streaming. Rather than using one single-to-many connection, several single-to-single connections had to be used, which stressed the network. 2.3.7 Bad mobile support With the growing numbers of mobile applications, and the demanding from them for the Internet Protocol, a new problem arose. The roaming of connected mobile devices is still not easy. For IPv4 there is one technique, called Mobile IP [36, 23], but that works with so called home mobile agents and has a certain overhead. 2.3.8 Renumbering Renumbering, that means if you want to change you IP address, produces today a lot of overhead. Changing the address sometimes meant to be multihomed for a short time, in order not to loose connectivity to your customers. That also had influence on the size of the routing tables and the performance as well. 2.4 IPv4 now Would all these problems have remained until now, the Internet just would not work anymore. To cure all these drawbacks, many extensions to the protocol were made. They are described in a not negligible number of RFCs and resulted in a rather blown up and patched protocol. The problem with the depletion of IP address was solved by stricter allocation of addresses. It were not just complete subnets like a class B net which was assigned, but smaller parts. Therefore the subnet mask was established and the old system with the network and host part was abolished, see CIDR . It is now possible to run subnets of almost arbitrary size, resulting in a much better usage of addresses in a certain subnet. Another positive contribution to the address problem was the strong usage of Network Address Translation (NAT), which hided a whole (company) subnet behind just one IP address. That was on the one hand done to save IP address, but also to gain security of the data coming to and leaving from the subnet, as there was just one point were the data had to be controlled. One should mention that that caused other problems, like a single point of failure, if the NAT router crashed or problems if you want to be reachable from the outer net. And the general idea of the Internet, the end-to-end connection of the independent hosts was violated with this method. The router table problem was faced by using a new technique called route aggregation, introduced with BGP-4 . Pathes to subnets were aggregated in just one routing table entry. Roughly spoken that means, if there were before 3 entries in a table (lets say 22.214.171.124, 126.96.36.199, 188.8.131.52) and we knew that they belong to the same net, we just would make one entry out of them, namely 192.8.0/22, indicating that all packets belonging to that subnet should be routed to the same router. That required also a change in the allocation of addresses, meaning that coherent address ranges had to be given to the same provider. Multicast was implemented later, but remained withheld to local net structures. Some multicast networks were implemented, like the MBone , but that was just a bad workaround for the real problem. Several other drawbacks were also faced, as already mentioned above. Sometimes the developers just used the layers above to implement functions and features that IPv4 was lacking in their opinion, like IPSec or different Quality of Service (QoS) functions. Mobile IP is a nice extension, but just a add on and would scale well. As the header could not be changed, the inefficient layout is still used. 3. INTERNET PROTOCOL VERSION 6 3.1 The birth of IPv6 In the beginning of the 90s many people realised, that it was necessary to develop a new protocol for the Internet, due to the limitations of the very old and for these times not appropriate IPv4. An IPng (IP next generation) effort was started to solve these issues. After long discussions, which can be found in several RFCs, starting with RFC 1550 , IPv6  was elected to be the new protocol in 1995, as it was the merger of many good ideas. But the struggles did not stop, resulting to some redesigning of that protocol, leading to the final specification in RFC 2460 . These discussions and changing of the protocol was one main drawback, as already finished implementations had to be condemned. 3.2 What is new In the design phase of IPv6 the mail goal was to solve all the problems that arose during the usage of IPv4 in the growing Internet and provide future-proofness. So the main changes can be directly adapted from the downsides of IPv4. 3.2.1 New addresses The most remarkable change of course took place in the header, as the header contributes most to the def intion of a communication protocol. When designing the header the persons in charge were aware of the insufficient address length of version 4, so they extendend the address length to 128 bit. That results in the unimaginable big number of theoretical 3, 4 × 1038 addresses. It is possible to assign 6, 89×1017 to each square mm of the earth . But that are theoretical numbers, as the IP addresses are again separated in different parts. 184.108.40.206 Address format A close look to the format of the new addresses clarifies that. To understand it, it is necessary to know how the new addresses are represented. Notation is not any more dotted-decimal, but in 8 hexadecimal blocks of 16 bit each, separated by a colon. An example would be: Unicast: Anycast: Multicast: An identifier for a single interface. A packet sent to a unicast address is delivered to the interface identified by that address. An identifier for a set of interfaces (typically belonging to different nodes). A packet sent to an anycast address is delivered to one of the interfaces identified by that address (the ”nearest” one, according to the routing protocols’ measure of distance). An identifier for a set of interfaces (typically belonging to different nodes). A packet sent to a multicast address is delivered to all interfaces identified by that address. Table 2: IPv6 Address Type Identification  fier (TLA), Reserved for future use (RES), Next-Level Aggregation Identifier (NLA ID), Site-Level Aggregation Identifier (SLA ID) and given in these blocks to international and national registries or Internet service providers (Figure 9). That should result in a more efficient routing, but would also have created islands in the Internet with common prefixes. IP addresses would have been geographically dependent. Figure 7: IPv6 header  2001:0db8:85a3:08d3:1319:8a2e:0370:7344 To simplify the notation when dealing with long addresses, it is possible to leave out blocks with zeros and write instead two colons: 2001:0db8::1428:57ab is equal to 2001:0db8:0000:0000:0000:0000:1428:57ab, but 2001::25de::cade is a wrong notation, as it is not clear how many groups of zeros were left out where. 220.127.116.11 Address types There are, like in IPv4, several address types defined in IPv6, each with different semantics, especially to the routers. Figure 8 shows the general addressing architecture of IPv6, when the type of address is not specified. That is just a general scheme and has no practical meaning. | n bits | 128-n bits | +---------------------------------------------+----------------+ | subnet prefix | interface ID | +---------------------------------------------+----------------+ Figure 8: General addressing architecture In IPv6 there exist three types of addresses, which is shown in table 2: New is the anycast address. Note that broadcast is handled via multicast, by multicasting to the all-nodes group. The most interesting addresses are of course the global addresses, as they have to be routed through the whole Internet, and during the design phase of IPv6 the problem of the big routing tables was aware. In earlier implementations the developers thought of a hierarchically structured Internet, where complete address ranges would be separated in Top-Level Aggregation Identi- | 3| 13 | 8 | 24 | 16 | 64 bits | +--+-----+---+--------+--------+-------------------------------+ |FP| TLA |RES| NLA | SLA | Interface ID | | | ID | | ID | ID | | +--+-----+---+--------+--------+-------------------------------+ Figure 9: Addressing architecture, July 1998 Another proposal for the address architecture removed this strong separation in 2003. As it is apparent from figure, is it just distinguished between a global routing prefix, a subnet ID, and the interface ID. Depending on the type of addresses, the sizes of the fields vary, as indicated by n and m. The designers stated that it is up to the service providers and allocation authorities to allocate meaningful address spaces, that allow route aggregation like the CIDR and BGP-4 in IPv4. | n bits | m bits | 128-n-m bits | +------------------------+-----------+-------------------------+ | global routing prefix | subnet ID | interface ID | +------------------------+-----------+-------------------------+ Figure 10: Addressing architecture, April 2003 Table 3 gives a complete overview over the type of addresses. Global unicast addresses were already explained above. Analogical to IPv4 there is the unspecified address, when the interface is waiting for an address, and the loopback address, intended to send messages to itself. It is important that the semantics of IPv6 imply that we do not assign an address to a host or node, but to an interface. This becomes clearer when looking at the requirements a host must meet before it can communicate over IPv6. Anycast addresses are taken from the unicast address spaces (of any scope) and are not syntactically distinguishable from unicast addresses. A possible use could be to discover all the routers attached to a particular subnet. Multicast addresses have generally the same meaning like in IPv4, it is possibly to reach a group of host by sending Address type Unspecified Loopback Multicast Link-local unicast Global unicast Binary prefix 00...0 (128 bits) 00...1 (128 bits) 11111111 1111111010 (everything else) IPv6 notation ::/128 ::1/128 FF00::/8 FE80::/10 Table 3: Address Type Identification  just one packet, which saves bandwidth and router load. In IPv4 that was just possible in the local network, or via workarounds like the MBone, which did not scale. In IPv6 it is possible to set options when sending to a multicast group, so that the packets are routed through the Internet. In the current RFC 4291  there are currently six special multicast scopes given: • Interface-Local scope • Link-Local scope • Admin-Local scope • Site-Local scope • Organization-Local scope • Global scope These will be routed through the Internet. So it may be possible to send a multicast request to all NTP time servers that joined the global group in the whole Internet, by specifying a global scope multicast address. Link-Local addresses are for use on a single link. They have the 10 bit prefix as described above, then 54 bit of zeros, and the last 64 bit contain the interface identifier. They are used on single links and for automatic address configuration. Packets with these addresses must not be forwarded by routers. To identify himself, a host needs to meet certain criteria for his network interface card. The card has to have at least: 18.104.22.168 22.214.171.124 • Any additional Unicast and Anycast addresses that have been configured for the node’s interfaces (manually or automatically). • The loopback address. • The All-Nodes multicast addresses • The Solicited-Node multicast address for each of its unicast and anycast addresses. • Multicast addresses of all other groups to which the node belongs. Interoperability with IPv4 There are special address formats reserved in the IPv6 header, that guarantee interoperability with the old Internet Protocol. These special addresses belong to the global unicast address range. They start with a sequence of 80 zeros, and then 16 ones, and then the normal 32 bit global IP address. These addresses are called IPv4-Mapped IPv6 addresses and provide one part of the interoperability issues between IPv6 and IPv4. 3.2.2 Simplified header format As obvious from figure 7, the header is much simpler and does not contain as many fields as the header of version 4. That will lead to a much faster treatment by the router, resulting in more throughput. Many things were just left out, like fragment information checksum information and header length. The (main) header has now a defined length of 320 bit, additional headers will be located between the main header and the payload. This distinction make the header on the one hand efficiently routable, but provides enough flexibility for new extensions. IPv6 packets should not be fragmented, the size of a single IPv6 packet must be chosen by the sender according to the MTU of the data link layer. Checksum information was removed, too, that issue should be handled by layer 2 or layer 4 (e.g. TCP). All these simplifications will increase the speed when a packet has to cross many routers. The semantics of the old TTL field has now changed to the actual meaning, HOPs, which defines the maximum number of routers that can be passed. The original meaning of TTL was the time a packet should live. Flowlabel and class in the IPv6 header will be used for Quality of Service, advising the routers how to prioritize the packet. 3.2.3 • Its required Link-Local address for each interface. Interface Identifiers The 64 bit interface identifier is, in case we use ethernet, created out of the 48 bit MAC address of the network interface card with a simple mapping and should be unique. As this identifier can be seen in the public IP address, some suggestions were made not to loose privacy with this mechanism ??. Now, the interface identifier is made with special algorithms, ensuring obfuscation of the real hardware address. For other data links as the ethernet there are special algorithms to generate this identifier. Address autoconfiguration It is still possible to configure a host manually, or to techniques similar to IPv4 DHCP. But new is that a host can generate itself a valid IP address , by using his interface identifier and the prefixes announced by present routers. Even if now routers are present, it is possible to communicate with neighbours without any configuration . These techniques can be even combined with DHCPv6  to gain additional information like nameservers. 3.2.4 Renumbering Renumbering is made much easier. The details are quite complicated and are nor scope of this document. Ressources can be found in RFC 4076 . 3.2.5 Security features In the first implementations of IPv4 there were no security mechanisms that were assuring that a packet could not be altered and seen during the way through the network. Now there are extensions like IPSec, but they are not mandatory. Both hosts have to implement the used security protocols. In IPv6 a technique similar to IPSec is used, and is mandatory for the IP protocol stack. This is made possible by one of the extension headers. There is now real data security on the network layer. Problems that also arose with IPSec and IPv4 were the limitations due to the use of NAT, as the real sending address was changed by the NAT router. NAT is generally not necessary with IPv6 and should not be used. Instead it is recommended to use other filter techniques to protect certain networks. 3.2.6 Quality of Service The Quality of Service capability of IPv4 was quite bad and inefficiently solved. For upcoming applications that was not sufficient. In IPv6 there are two fields reserved to provide QoS functionality, though it is yet not completely clear, how the exact implementation will be. For the flow label field there is one proposal in RFC 3697 . The other useable field is traffic class. 3.2.7 Mobile IP Mobile applications are growing, there are estimations for over 2 milliard mobile users in the year 2007. To serve them all with the services desired, it is necessary to create the underlying infrastructure properly. Many see the IPv6 as one of the backbone architectures for these growing market [21, 22, 13]. With the larger address space all mobile devices imaginable could be addressed. But IPv6 provides also good strategies when moving the devices from one network to another. There are some solutions for IPv4, like home-agents and foreign-agents , which is also possible for IPv6. There are new researches on how to use the underlying IPv6 architecture to simplify and enhance the home and foreign-agent method by just sending some messages over these relays and then switch to a direct connection, making use of the IPv6 extension headers . 3.3 Advantage of IPv6 over IPv4 To sum up the advantages of IPv6 over IPv4 it is almost sufficient to reread the previous chapter. When designing the new version, all the drawbacks were in mind and so the best attempts were many so solve them. Big advantages are, as already pointed out, the great mobility support, the QoS enhancement, the routing table aggregation and the larger address space. Though many of these problems very later solved in extensions to the IPv4 protocol, the old protocol looks a a piece of software that was just patched for over 20 years. The IPv6 is much more elegant and redesigned almost from scratch. As it will not be necessary to use NAT, it will be much easier to use peer-to-peer applications like VoIP and Instant Messaging - a definite future trend - as the endto-end paradigm is restored. Due to the auto configuration mechanisms, the network administration costs of companies will also be reduced. 3.4 3.4.1 Switching to IPv6 Situation A disadvantage is obviously the migration or switching from IPv4 to IPv6. There is an estimation about the costs of about $75 milliard just for the United States. This should not be considered as the biggest problem, as the infrastructure has to renewed in certain intervals nevertheless. Some reports even state out that upgrading to the new version would yield in just the market for durable goods (e.g. automobiles) to benefits of over $3 milliard each year . Another hard issue is the fact that the current IPv4 with all its extensions is working well for many companies and that they do not see the need to switch. In North America and Europe there are, due to historic reasons considering the allocations of IPv4 address ranges, still enough IPv4 addresses left, so the need is much lower than for example in Asia. This continent is a driving force for the IPv6 deployment, but many decisions are taken by Europe and the US. The migration phase will also be hard to manage. It will not be possible to switch the whole Internet from one day to another from version 4 to version 6. So there will be a migration phase, were IPv4 and IPv6 will coexist. There are many methods to face these problems . One explained above is that the designers of IPv6 reserved some special addresses in the IPv6 address range for IPv4-mapped IPv6 addresses. With these addresses it is possible for a host to make a DNS query for the IPv6 address of an IPv4 host. These methods can be used within dual stack hosts, which support both IPv4 and IPv6. Other techniques are tunneling, where the IPv6 packets are packed into an IPv4 packet in order to be able to use the existing IPv4 infrastructure. The packets will be unpacked and processed at the destination host. It is also possible to use a kind of proxy at some border points of networks, where the different versions are translated. To support both IPv4 and IPv6 at the same time, it is important to get the right addresses when performing a DNS query. BIND [?], the most used DNS server software, supports both IPv4 and IPv6 queries. The IPv4 addresses are stored in a so called A record. To support Ipv6 an AAAA record was created, which holds the IPv6 address of a certain host. 3.4.2 Which OS is IPv6 ready The following list gives a small overview over common operating systems and their efforts towards IPv6: • BSD - At the moment the best support for IPv6 , but no IPv4-to-IPv6-Mapping implemented. • AIX - Since version 5.2 even with Mobil IP • Cisco - Productive support since IOS version 12.3 • Linux - similar support like BSD • Mac OS X - Support since version 10.2 • Windows XP - must be explicitly turned on, but it is possible since SP2 4. CONCLUSION AND OUTLOOK Today almost all traffic of the Internet is done with IPv4. There are no other protocols, if we leave out the few IPv6 islands that are used in the Internet. A switching, respectively migrating means that IPv4 would be replaced by IPv6. As mentioned above, there are different groups of interests. To many companies and other persons using the Internet changing just means no benefits, but high costs , as the have so buy new soft and hardware. The actual version normally gives them the opportunities they need. On they other hand there are the big software, hardware and mobile application manufactures. They clearly see the need for a better protocol, facing problems like bad mobility support, lack of security features, address depletion in certain areas of the world. They have s strong desire in deploying the IPv6 quite soon. It is very important for the success of a new technology how the great companies with the biggest market-share stand toward it. Major players like Microsoft, Cisco and mobile telephone companies are investing big sums in research for IPv6. With the support of the new protocol in MS Windows a big entry barrier has been removed, due to the spread of Windows on consumer computers. Governments and several organisations, as well as big companies, are preparing studies in order not to loose track in the recent development. Countries in Asia, like Japan, China and Korea are much further in using and testing IPv6. One reason is the limited amount of IPv4 addresses they received. If the growth of the economy in China continues, there will soon be 500 million mobile phone users and an equal number of Internet users. That will not be possible with the IPv4 addresses available. The world can not close its eyes to this new technology. Future trends are demanding special infrastructure like security and mobility. Devices will be always connected to the Internet (always on), and will keep their address. Applications like VoIP, peer-to-peer and smartphones will gain great success. That is simply not possible with IPv4. In spite of the costs that we are facing, the question is not anymore if and if yes, when, but when. And the date, when the last IPv4 application will stop operating is coming nearer and nearer, and always faster. 5. REFERENCES  AS1221 BGP Table Statistics. http://bgp.potaroo.net/as1221/bgp-active.html.  Join Uni Münster. http: //www.join.uni-muenster.de/Join/index_join.php.  KAME Project. http://www.kame.net/.  www.isc.org. http://www.isc.org/index.pl?/ops/ds/hosts.php.  S. Bradner and A. Mankin. RFC 1550 - IP: Next Generation (IPng) White Paper Solicitation. http://www.ietf.org/rfc/rfc1550.txt, December 1993.  Cisco Systems. The Coming Internet Evolution: IPv6 And Its Implications For The Service Provider Marketplace. Technical report.  D. Johnson, C. Perkins and J. Arkko. RFC 3775 Mobility Support in IPv6. http://www.ietf.org/rfc/rfc3775.txt, June 2004.  S. Deering and R. Hinden. RFC 1883 - Internet Protocol, Version 6 (IPv6) Specification. http://www.ietf.org/rfc/rfc1883.txt, December 1995.  S. Deering and R. Hinden. 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