Guide to TCP/IP, Third Edition Chapter 13: Internet Protocol Version 6

2 Objectives Understand the limitations of IPv4 and how the creation of IPv6 helps to overcome them Understand the structure and capabilities of the new IPv6 address space Consider how routing is affected under IPv6

Internet Protocol Version 63 Objectives (continued) Understand IPv6 packet formats Discuss new and enhanced IPv6 features Understand how IPv6 and IPv4 coexist, and how to use both versions simultaneously Understand impediments involved in transitioning from IPv4 to IPv6

Internet Protocol Version 64 Why Create a New Version of IP? IPv4 address space –Recognizes only four billion unique IP addresses in round numbers Usable address space –Number of hosts that could actually be connected to the Internet Most critical shortcoming of IPv4 –Lack of universally valid IP addresses

Internet Protocol Version 65 The IPv6 Address Space IPv6 solves address shortage problem by –Creating address space that is more than 20 orders of magnitude larger than IPv4’s address space IPv6 address space –Provides hierarchy in a flexible and well-articulated fashion with room for future growth

Internet Protocol Version 66 Address Format and Allocations IPv6 address –128 bits long –String that uniquely identifies one single network interface on the global Internet If entity is on the same subnet as the host –Both share a large part of that address

Internet Protocol Version 67 Address Format and Allocations (continued) Scope identifier –Four-bit field that limits the valid range for a multicast address IPv6 –Requires each single interface within each device to have its own unique interface identifier –Specifies that interface identifiers follow the Modified EUI-64 format

Internet Protocol Version 68

9 Address Format and Allocations (continued) IPv4-compatible address and the IPv4-mapped address –IETF defined type IPv6 addresses that contain IPv4 addresses within them RFC 2732 –Describes a method to express IPv6 addresses in a form compatible with HTTP URLs

Internet Protocol Version 610 Address Types Unspecified address –All zeroes and can be represented as two colon characters (::) in normal notation No broadcast address in IPv6 Multicast addresses in IPv6 –Used to send an identical message to multiple hosts Solicited node address –Used to support Neighbor Solicitation (NS)

Internet Protocol Version 611

Internet Protocol Version 612

Internet Protocol Version 613

Internet Protocol Version 614 Address Types (continued) Anycast address –Used to address functions commonly deployed on the Internet at multiple network locations Unicast address –Sent to one network interface Aggregatable global unicast address –Can be combined with other addresses into a single entry in the router table

Internet Protocol Version 615

Internet Protocol Version 616 Address Types (continued) Link-local address –Has its first 10 (leftmost) bits set to Site-local address –Has its first 10 (leftmost) bits set to IPv6 –Pre-allocates only about 15% of its available addresses –Address space set aside for addresses using Network Service Access Point (NSAP) type addressing

Internet Protocol Version 617

Internet Protocol Version 618

Internet Protocol Version 619 Routing Considerations IPv6 –Designed from the ground up with routing efficiency and throughput in mind –Designed to reduce the workload of Internet routers –Allocation schemes attempt to build in as much aggregatability as possible without “tyrannizing” users

Internet Protocol Version 620 Neighbor Discovery and Router Advertisement ND uses five ICMP message types –Router Solicitation (RS) –RouterAdvertisement (RA) –Neighbor Solicitation (NS) –Neighbor Advertisement (NA) –Redirect

Internet Protocol Version 621 Path MTU Discovery and Changes in Fragmentation Senders are required to –Check the Path MTU (PMTU) between themselves and the destination before they send –Size packets accordingly Every network segment or link has its own MTU

Internet Protocol Version 622 Working with IPv6 Protocols Mechanisms that IPv6 uses to handle name resolution Native packet formats and field layouts used in IPv6 Mechanisms used to support automatic address assignment or allocation Security enhancements Manage service levels and priorities for different types of traffic

Internet Protocol Version 623 Nam Resolution in IPv6 Domain Name System (DNS) –Continues to operate in IPv6 environments where it is known as DNSv6 What IPv6 offers that IPv4 does not –Backup service that can stand in for DNS Link Local Multicast Name Resolution (LLMNR) protocol –Uses same message format that conventional DNS also uses, but runs on different ports

Internet Protocol Version 624 IPv6 Packet Formats IPv6 packets –Consist of a fixed, constant format 40-byte header, optional extension headers, and the payload (data) All encapsulated within a Data Link layer frame IPv6 header –Designed to reduce processing time at the destination and on intervening routers

Internet Protocol Version 625

Internet Protocol Version 626 Basic IPv6 Header Format IPv6 header format differs from IPv4 packet structure in the following ways –Six IPv4 header fields were removed Internet Header Length, Type of Service Identification, Flags, Fragment Offset Header Checksum –Three IPv4 fields were renamed or altered Total Length, Protocol, and Time to Live –Two new fields were added Class and Flow Label

Internet Protocol Version 627

Internet Protocol Version 628 Extension Headers Recommended order for the extension headers –1. Hop-by-Hop Options –2. Destination Options –3. Routing –4. Fragment –5. Authentication –6. Encapsulating Security Payload (ESP) –7. Destination Options

Internet Protocol Version 629

Internet Protocol Version 630 New and Enhanced IPv6 Features Autoconfiguration –Allows host to find the information it needs to set up its own IP networking parameters DHCP –Common autoconfiguration tool deployed across many parts of the Internet today

Internet Protocol Version 631 Autoconfiguration Three things combine to make autoconfiguration important for the Internet –The sheer number of nodes to be configured –The rate of change and the frequency of renumbering –User mobility

Internet Protocol Version 632 Stateless Autoconfiguration RFC 2462 –Proposes tools to support stateless autoconfiguration of attached nodes Stateless autoconfiguration –Can be used alone or in conjunction with a stateful autoconfiguration method, such as DHCPv6 Routers on the local link –Can be configured to provide pointers to DHCPv6 servers

Internet Protocol Version 633 Security May mean –The ability to detect alterations made to a communication after some point in time –The ability to check the credentials of a user to keep or share a secret Biggest change from IPv4 to IPv6 –Security, in the form of IPSec, is a required part of IPv6

Internet Protocol Version 634 Terms of Encryption Computer security –Based on sets of mathematical manipulations called transformations Encryption –Used to keep communications secret or private Ciphertext –Scrambled document Compression –Attempts to find patterns in the plain text and express those patterns in fewer characters

Internet Protocol Version 635 Quality of Service The ability of a network to provide better service to specific types of network traffic Handled by the diffserv working group at the IETF Resource Reservation Protocol (RSVP) –Early attempt to promote a more formal approach to dynamic resource allocation on the Internet

Internet Protocol Version 636 Router Alerts and Hop-by-Hop Options IPv6 header –Eliminates all the fields relating to QoS RFC 2711 –Defines the router alert option in the Hop-by-Hop Options extension header Router alert option –Tells intervening routers to examine the packet more closely for important information

Internet Protocol Version 637

Internet Protocol Version 638

Internet Protocol Version 639 Mobile Users Micro-mobility –Generally dealt with at the link layer, below IP –Maintains connectivity to a local link over a wireless connection Ordinary mobility –Takes place on a slightly larger scale, such as logging onto a network in Copenhagen

Internet Protocol Version 640 Coexistence of IPv4 and IPv6 Dual stack –Implementations for individuals or small offices may work as experiments, but Are limited by the availability of dual stack routers at ISPs at the edge of the Internet Most important dual stack machines –Will be the routers themselves Dual stack router –Can provide a connection between the IPv4 Internet and an office that already made the switch to IPv6

Internet Protocol Version 641 Tunneling Through the IPv4 Cloud Internet –Will probably move to IPv6 “from the edges in” IPv6 will be adopted –First by smaller organizations with greater flexibility and higher tolerance for difficulties of pioneering

Internet Protocol Version 642 IPv6 Rate of Adoption Biggest push for the adoption of IPv6 I –Coming from those who were not a part of the initial Internet “land rush” of the 1990s New technologies (cellular phones) have two reasons to embrace IPv6 –They want the address space –Communications technologies need the improved functionality of the IPv6 protocol suite

Internet Protocol Version 643 Transitioning to IPv6: The Reality Reaction of industry participants to potential of IPv6 –Initially, service provider segment of the market pushed for the protocol –Router and switch vendors saw the protocol as a marketing opportunity –Engineers in the service provider space saw IPv6 as a solution to solve a specific problem

Internet Protocol Version 644 Interoperability One technology can work together with another technology Network address translation (NAT) –Used to provide translation between private IP addresses and public IP addresses Transitioning to IPv6 –The movement of deploying IPv6 throughout a production environment

Internet Protocol Version 645 Network Elements Clients Servers Routers Gateways VoIP networks Network management nodes Transition nodes Firewalls

Internet Protocol Version 646 Software Tools and utilities designed to monitor, report on, and manage network infrastructure elements –Network management and utilities –Network Internet infrastructure applications –Network systems applications –Network end-user applications –Network high-availability software –Network security software

Internet Protocol Version 647 Transitioning to IPv6 from the Windows Perspective Microsoft provides support for IPv6 implementations for –Windows Server 2003 –Windows XP with Service Pack 1 (or higher) –Windows CE.NET 4.1 Microsoft –Supports the Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)

Internet Protocol Version 648 Availability Most of the IPv6 deployments are –In Asia and Europe –In areas that were behind the deployment of IPv4 infrastructures These environments are ahead of the curve for two reasons –Market is forcing IPv6 onto the consumers, which creates demand for provider support –A lot of the solutions are deployed initially with IPv6

Internet Protocol Version 649 Summary Adopting the new version of the Internet Protocol –Would solve the IP address shortage For backward compatibility –IPv6 defines two mechanisms (IPv4-compatible and IPv4-mapped addresses) IPv6 supports great improvements to –Communications security, auto-configuration –Quality of Service handling –Routing efficiency and mobile use

Internet Protocol Version 650 Summary (continued) IPv6 builds on lessons learned in IPv4 to –Streamline headers, allocate and aggregate addresses, and generally improve routing behavior IPv6 introduces a Neighbor Discovery protocol Basic IPv6 packet format –Redesigned to streamline processing time en route to and at its intended destination(s) IPv6 makes it easier to renumber networks than with IPv4

Internet Protocol Version 651 Summary (continued) IPv6 –Embeds robust, built-in security in its required core implementation –Incorporates incremental updates to most core IP protocols Mobile IPv6 –Enables mobile users to operate even though they may move from one location to another Obstacles to widespread deployment of IPv6 –IPv4/IPv6 interoperability –Availability of IPv6 addresses