Introduction to IP Version 6

Operating System

Introduction to IP Version 6

White Paper

Abstract

Due to recent concerns over the impending depletion of the current pool of Internet addresses and the desire to provide additional functionality for modern devices, an upgrade of the current version of the Internet Protocol (IP), called IPv4, is in the process of standardization. This new version, called IP Version 6 (IPv6), resolves unanticipated IPv4 design issues and is poised to take the Internet into the 21st Century. This paper describes the problems of the IPv4 Internet and how they are addressed by IPv6, IPv6 addressing, the new IPv6 header and its extensions, the IPv6 replacements for the Internet Control Message Protocol (ICMP) and Internet Group Management Protocol (IGMP), neighboring node interaction, and IPv6 address autoconfiguration. This paper provides a foundation of Internet standards-based IPv6 concepts and is intended for network engineers and support professionals who are already familiar with basic networking concepts and TCP/IP.

The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the date of publication. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication.

This white paper is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS OR IMPLIED, IN THIS DOCUMENT.

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6/2000

CONTENTS

INTRODUCTION 1

IPv6 Features 2

New Header Format 2

Large Address Space 2

Efficient and Hierarchical Addressing and Routing Infrastructure 3

Stateless and Stateful Address Configuration 3

Built-in Security 3

Better Support for QoS 3

New Protocol for Neighboring Node Interaction 3

Extensibility 3

Differences Between IPv4 and IPv6 3

IPv6 Packets over LAN Media 5

Ethernet II Encapsulation 5

IEEE 802.3, IEEE 802.5, and FDDI Encapsulation 5

Microsoft IPv6 Implementations 6

Microsoft Research IPv6 Implementation 6

Microsoft IPv6 Technology Preview for Windows 2000 7

IPV6 ADDRESSING 8

The IPv6 Address Space 8

Current Allocation 8

IPv6 Address Syntax 9

Zero Compression 10

IPv6 Prefixes 10

Types of IPv6 Addresses 11

Links and Subnets 11

Unicast IPv6 Addresses 11

Aggregatable Global Unicast Addresses 12

Local-Use Unicast Addresses 13

Special IPv6 Addresses 15

Compatibility Addresses 15

NSAP and IPX Addresses 15

Multicast IPv6 Addresses 16

Solicited-Node Address 17

Anycast IPv6 Addresses 18

IPv6 Addresses for a Host 19

IPv6 Addresses for a Router 19

IPv6 Interface Identifiers 19

IEEE 802 Addresses 20

IEEE EUI-64 Addresses 21

Obtaining Interface Identifiers for IPv6 Addresses 21

Mapping IPv6 Multicast Addresses to Ethernet Addresses 23

IPv6 and DNS 24

The Host Address (AAAA) Resource Record 24

The IP6.INT Domain 24

IPv4 Addresses and IPv6 Equivalents 24

IPV6 HEADER 26

IPv4 Header 26

Structure of an IPv6 Packet 27

IPv6 Header 28

Extension Headers 28

Upper Layer Protocol Data Unit 28

IPv6 Header 28

Values of the Next Header Field 30

Comparing the IPv4 and IPv6 Headers 30

IPv6 Extension Headers 31

Extension Headers Order 32

Hop-by-Hop Options Header 32

Destination Options Header 33

Routing Header 34

Fragment Header 34

Authentication Header 36

Encapsulating Security Payload Header and Trailer 37

IPv6 MTU 37

Upper Layer Checksums 38

ICMPV6 39

Types of ICMPv6 Messages 39

ICMPv6 Header 39

ICMPv6 Error Messages 40

Destination Unreachable 40

Packet Too Big 41

Time Exceeded 42

Parameter Problem 42

ICMP v6 Informational Messages 43

Echo Request 43

Echo Reply 43

Comparing ICMPv4 and ICMPv6 Messages 44

Path MTU Discovery 45

Changes in Path MTU 45

MULTICAST LISTENER DISCOVERY 46

Multicast Listener Query 46

Multicast Listener Report 47

Multicast Listener Done 48

NEIGHBOR DISCOVERY 49

Neighbor Discovery Message Format 50

Neighbor Discovery Options 51

Source/Target Link-Layer Address Option 51

Prefix Information Option 52

Redirected Header Option 54

MTU Option 54

Neighbor Discovery Messages 56

Router Solicitation 56

Router Advertisement 57

Neighbor Solicitation 59

Neighbor Advertisement 60

Redirect 62

Neighbor Discovery Processes 64

Address Resolution 64

Duplicate Address Detection 66

Router Discovery 68

Neighbor Unreachability Detection 70

Redirect Function 73

Host Sending Algorithm 76

ADDRESS AUTOCONFIGURATION 78

Autoconfigured Address States 78

Types of Autoconfiguration 79

Autoconfiguration Process 79

SUMMARY 83

For More Information 83

INTRODUCTION

The current version of IP (known as Version 4 or IPv4) has not been substantially changed since RFC 791 was published in 1981. IPv4 has proven to be robust, easily implemented and interoperable, and has stood the test of scaling an internetwork to a global utility the size of today’s Internet. This is a tribute to its initial design.

However, the initial design did not anticipate the following:

• The recent exponential growth of the Internet and the impending exhaustion of the IPv4 address space.

IPv4 addresses have become relatively scarce, forcing some organizations to use a Network Address Translator (NAT) to map multiple private addresses to a single public IP address. While NATs promote reuse of the private address space, they do not support standards-based network layer security or the correct mapping of all higher layer protocols and can create problems when connecting two organizations that use the private address space.

Additionally, the rising prominence of Internet-connected devices and appliances ensures that the public IPv4 address space will eventually be depleted.

• The growth of the Internet and the ability of Internet backbone routers to maintain large routing tables.

Because of the way that IPv4 network IDs have been and are currently allocated, there are routinely over 70,000 routes in the routing table of the Internet backbone routers. The current IPv4 Internet routing infrastructure is a combination of both flat and hierarchical routing.

• The need for simpler configuration.

Most current IPv4 implementations must be either manually configured or use a stateful address configuration protocol such as Dynamic Host Configuration Protocol (DHCP). With more computers and devices using IP, there is a need for a simpler and more automatic configuration of addresses and other configuration settings that do not rely on the administration of a DHCP infrastructure.

• The requirement for security at the IP level.

Private communication over a public medium like the Internet requires encryption services that protect the data being sent from being viewed or modified in transit. Although a standard now exists for providing security for IPv4 packets (known as Internet Protocol security or IPSec), this standard is optional and proprietary solutions are prevalent.

• The need for better support for real-time delivery of data—also called quality of service (QoS).

While standards for QoS exist for IPv4, real-time traffic support relies on the IPv4 Type of Service (TOS) field and the identification of the payload, typically using a UDP or TCP port. Unfortunately, the IPv4 TOS field has limited functionality and over time there were various local interpretations. In addition, payload identification using a TCP and UDP port is not possible when the IPv4 packet payload is encrypted.

To address these concerns, the Internet Engineering Task Force (IETF) has developed a suite of protocols and standards known as IP version 6 (IPv6). This new version, previously

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