Internet Protocol version 6 (IPv6) Conformanc…

Figure 1. IPv6 address format.

Benefits of IPv6

Aside from the increased address space, IPv6 offers a number of other key design improvements over IPv4.

Improved efficiency in routing and packet handling
IPv6抯 very large addressing space and network prefixes (Figure 1) allow the allocation of large address blocks to ISPs and other organizations. This enables an ISP or enterprise organization to aggregate the prefixes of all its customers (or internal users) into a single prefix and announce this one prefix to the IPv6 Internet.

Within the IPv6 address space, the implementation of a multi-leveled address hierarchy provides more efficient and scalable routing. This hierarchical addressing structure reduces the size of the routing tables Internet routers must store and maintain.

Though the IPv6 header is larger, its format is simpler than that of the IPv4 header. The IPv6 header removes the IPv4 fields for Header Length (IHL), Identification, Flags, Fragment Offset, Header Checksum, and Padding, which speeds processing of the basic IPv6 header. Also, all fields in the IPv6 header are 64-bit aligned, taking advantage of the current generation of 64- bit processors.

Support for autoconfiguration and plug and play
The need for plug-and-play autoconfiguration and address renumbering has become increasingly important to accommodate mobile services (data and voice) and Internetcapable appliances. IPv6抯 built-in address autoconfiguration feature enables a large number of IP hosts to easily discover the network and obtain new, globally unique IPv6 addresses. This allows plug-and-play deployment of Internet-enabled devices such as cell phones, wireless devices, and home appliances.

The autoconfiguration feature also makes it simpler and easier to renumber an existing network. This enables network operators to manage the transition from one provider to another more easily.

Support for embedded IPSec
Optional in IPv4, IPSec is a mandatory part of the IPv6 protocol suite. IPv6 provides security extension headers, making it easier to implement encryption, authentication, and virtual private networks (VPNs). By providing globally unique addresses and embedded security, IPv6 can provide end-to-end security services such as access control, confidentiality, and data integrity with less impact on network performance.

Enhanced support for Mobile IP and mobile computing devices
Mobile IP, defined in an IETF standard, allows mobile devices to move around without breaking their existing connections ?an increasingly important network feature. Unlike IPv4, IPv6 mobility uses built-in autoconfiguration to obtain the Care-Of-Address, eliminating the need for a Foreign Agent. In addition, the binding process allows the Correspondent Node to communicate directly with the Mobile Node, avoiding the overhead of triangular routing required in IPv4. The result is a much more efficient Mobile IP architecture in IPv6.

Elimination of the need for network address translation (NAT)
NAT was introduced as a mechanism to share and reuse the same address space among different network segments. While it has temporarily eased the problem of IPv4 address shortage, it has also placed a burden on network devices and applications to deal with address translation. IPv6抯 increased address space eliminates the need for address translation, and with it, the problems and costs associated with NAT deployment.

Support for widely deployed routing protocols.
IPv6 maintains and extends support for existing Interior Gateway Protocols (IGPs) and Exterior Gateway Protocols (EGPs). For example, OSPFv3, IS-ISv6, RIPng and MBGP4 have been well defined to support IPv6.

Increased number of multicast addresses, and improved support for multicast.
IPv6 multicast completely replaces IPv4 broadcast functionality, by handling IPv4 broadcast functions such as router discovery and router solicitation requests. Multicast saves network bandwidth and improves network efficiency.

What is IPv6?

IPv6 header format
The IPv6 header has been streamlined for efficiency (Figure 2). The new format introduces the concept of an extension header, allowing greater flexibility to support optional features. Fields in the IPv6 header are:

• Version: 4-bit Internet Protocol version number, value = 6.
• Traffic Class: 8-bit traffic class field, similar to type of service in IPv4.
• Flow Label: 20-bit flow label, used to identify traffic flow for additional control on quality of service.
• Payload Length: 16-bit unsigned integer, length of the IPv6 payload.

  标签：

  版权申明：本站文章部分自网络，如有侵权，请联系：west999com@outlook.com
  特别注意：本站所有转载文章言论不代表本站观点，本站所提供的摄影照片，插画，设计作品，如需使用，请与原作者联系，版权归原作者所有