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IPv6: Need and TrendsGirish B Hampali <shylabanu@technologist.com>
AbstractThis memo introduces the need of IPv6 and its trends in the current Internet. Suggestions and comments are requested. Distribution of this memo is unlimited. IPv6: Need and TrendsThe network layer protocol, Internet Protocol (IP), was designed in September 1981 for use in interconnected systems of packet-switched computer communication networks. The design goal of the network layer protocol was to provide the best effort way to transport datagrams from source to destination without regard to their network or any associated networks. The purpose of IP is to move datagrams through an interconnected set of networks. In IP, datagrams are routed based on the Internet address. Internet addresses are defined and are of a fixed length of four octets (32 bits). Internet addresses have multiple classes. Addresses are comprised of network identifiers and host identifiers. IP has been serving the Internet community for the last 20 years. The present trends and requirements of the Internet are entirely different and will be more different in the days to come. The key problems with the present addressing scheme are: the difficulty of configuration, the finite amount of address space, and its inability to cater to the needs of the present networking world. Various mechanisms were developed as solutions to alleviate these limitations, including Dynamic Host Configuration Protocol (DHCP) and Network Address Translation (NAT). These are sufficient, but have their own limitations. Hence, the network world started hunting for a new addressing mechanism. It was destined to find a specific future direction for the replacement of the current version of IP, and the result was IPv6. Engineering is not a task -- it's a phenomenon. You engineer something and require re-engineering; IPv6 is an effort in re-engineering IP. IPv6 protocol recommendation includes a simplified header with a hierarchical address structure that permits rigorous route aggregation. In addition, it is large enough to meet the needs of the Internet for the foreseeable future. The protocol also includes packet-level authentication and encryption along with plug and play auto-configuration. It also includes the ability to label traffic flows. IPv6 is an evolutionary step, rather than revolutionary, from IPv4. Functions that are generally seen as working in IPv4 are kept in IPv6. Functions that don't work or are infrequently used are either removed or made optional. Few new features are added where the functionality was felt to be necessary. IPv6 is designed to enable high performance and scalability. Scalable networking requires careful utilization of human resources as well as network resources. Some of the important features of IPv6 are:
IPv6 addresses are 128 bits long. There are three types of IPv6 addresses: Unicast, Anycast, and Multicast. Unicast addresses identify a single interface. Anycast addresses identify a set of interfaces, such that a packet sent to an anycast address will be delivered to one member of the set. Multicast addresses identify a group of interfaces, such that a packet sent to a multicast address is delivered to all of the interfaces in the group. There are no broadcast addresses in IPv6; their function has been superseded by multicast addresses. IPv6 addresses are 4 billion times the size of the IPv4 address space. This works out to be 340,282,366,920,938,463,463,374,607,431,768,211,456. The '6bone' is an international IPv6 test-bed network. It provides testing of IPv6 implementations and standards, and testing of transition strategies. A diverse community of users, ISP's and developer organizations are involved. To date, '6bone' has tested numerous implementations of IPv6 hosts and routers produced by data-com giants like Cisco Systems, 3Com, Bay Networks (which is now part of Nortel Networks), Digital Equipment Corp. (now owned by Compaq) and Fujitsu. The University of New Hampshire's InterOperability Laboratory is another testing venue of IPv6. IPv6 is aimed as a simple and flexible transition from IPv4. Rapid adoption of IPv6 is not possible; at the same time, we cannot wait till IPv4 address space is exhausted. It is clear that the transition must to be completed before IPv4 routing and addressing breaks. The transition will be much easier if IPv4 addresses are still globally unique. The other two transition requirements are flexibility of deployment and the ability for IPv4 hosts to communicate with IPv6 hosts. There will be IPv6-only hosts, just as there will be IPv4-only hosts. The capability must exist for IPv6-only hosts to communicate with IPv4-only hosts globally while IPv4 addresses are globally unique. Many upgraded hosts and routers will need to retain downward compatibility with IPv4 devices for an extended time period. Further Reading
RFC 2373 IP Version 6 Addressing Architecture
RFC 2374 An IPv6 Aggregatable Global Unicast Address Format
RFC 2460 Internet Protocol, Version 6 (IPv6) Specification
RFC 2461 Neighbor Discovery for IP Version 6 (IPv6)
RFC 2462 IPv6 Stateless Address Auto-configuration
RFC 2463 Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification
RFC 1886 DNS Extensions to support IP version 6
RFC 1887 An Architecture for IPv6 Unicast Address Allocation
RFC 1981 Path MTU Discovery for IP version 6
RFC 2023 IP Version 6 over PPP
RFC 2080 RIPng for IPv6
RFC 2452 IP Version 6 Management Information Base for the Transmission Control Protocol
RFC 2454 IP Version 6 Management Information Base for the User Datagram Protocol
RFC 2464 Transmission of IPv6 Packets over Ethernet Networks
RFC 2465 Management Information Base for IP Version 6:Textual Conventions and General Group
RFC 2466 Management Information Base for IP Version 6:ICMPv6 Group
RFC 2467 Transmission of IPv6 Packets over FDDI Networks
RFC 2470 Transmission of IPv6 Packets over Token Ring Networks
RFC 2472 IP Version 6 over PPP
RFC 2473 Generic Packet Tunneling in IPv6 Specification
RFC 2507 IP Header Compression
RFC 2526 Reserved IPv6 Sub-net Anycast Addresses
RFC 2529 Transmission of IPv6 over IPv4 Domains without Explicit Tunnels
RFC 2545 Use of BGP-4 Multi protocol Extensions for IPv6 Inter-Domain Routing
RFC 2590 Transmission of IPv6 Packets over Frame Relay
RFC 2675 IPv6 'Jumbograms'
RFC 2710 Multicast Listener Discovery (MLD) for IPv6
RFC 2711 IPv6 Router Alert Option
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