Guide To TCP/IP, Second Edition

Guide to TCP/IP, Second Edition 1

Guide To TCP/IP, Second Edition

Chapter 13

Internet Protocol Version 6 (IPv6)


Objectives

• Understand the limitations of IPv4 and how the creation of IPv6 can overcome them

• Understand the structure and capabilities of the new IPv6 address space and how it is used

• Consider how routing will be affected under IPv6• Understand IPv6 packet formats


Objectives (cont.)

• Discuss new and enhanced IPv6 features such as autoconfiguration, security, Quality of Service, and Mobile IP

• Understand the coexistence of IPv6 and IPv4, and how to use both versions simultaneously during the long transition from IPv4 to IPv6

• Understand the impediments involved in transitioning from IPv4 to IPv6


Why Create A New Version Of IP?

• Lack of universally valid IP addresses

• Classless Inter-domain Routing

• Network Address Translation

• “Private” IP addresses

• DHCP


The IPv6 Address Space

• Address format and allocations– Address format and notations

• FEDC:BA45:1234:3245:E54E:A101:1234:ABCD

• 1018:FD0C:0:9:90:900:10BB:A

– Network and host address

– Scope identifier

– Interface identifiers

– IPv6 addresses that contain IPv4 addresses

– A proposal for native IPv6 addresses in URLs


The IPv6 Address Space (cont.)



• Address types– Special addresses– No more broadcasts– Multicast addresses– Anycast addresses– Unicast addresses– Aggregatable global unicast addresses– Link-local and site-local addresses











• Address allocations– NSAP allocations

• Point-to-point links

– Unicast and Anycast allocations• Assign address blocks to “exchanges” that make

further distributions

– Multicast allocations• OxFF




Routing Considerations

• Neighbor Discovery and Router Advertisements– Router Solicitation (RS)

– Router Advertisement (RA)

– Neighbor Solicitation (NS)

– Neighbor Advertisement (NA)

– Redirect

• Path MTU discovery and changes in fragmentation


IPv6 Packet Formats

• Basic IPv6 header format– Version Field

– Class Field

– Flow Label Field

– Payload Length Field

– Next Header Field

– Hop Limit Field

– Source IP Address Field

– Destination IP address Field


IPv6 Packet Formats (cont.)









• Extension headers– Hop-by-hop Options Extension Header– Destination Options Extension Header– Routing Extension Header– Fragment Extension Header– Authentication Extension Header– Encapsulating Security Payload Extension

Header
















New And Enhanced IPv6 Features

• Autoconfiguration– Stateless autoconfiguration

– Stateful autoconfiguration and DHCPv6

• Security– Terms of encryption

– Security architecture• Access control

• Connectionless integrity

• Data origin authentication


New And Enhanced IPv6 Features (cont.)

• Security (cont.)– Security architecture (cont.)

• Protection against replays

• Confidentiality

• Limit traffic flow confidentiality

– IPSec implementation and basic operation– Traffic mode and tunneling mode– Keys and coordination



• Quality of Service (QoS)– Per-hop behaviors (PHBs)– Per-domain behaviors (PDBs)

• Router alerts and hop-by-hop options– Jumbograms

• Mobil users– The mobile problem– Binding and routing for mobile IPv6






Coexistence Of IPv4 And IPv6

• Dual stack approach– Running two versions of IP

• Tunneling through the IPv4 cloud– Both ends of the tunnel must be dual stack routers

• IPv6 rate of adoption– Big push from

• Cellular technologies

• Mobile technologies


Transitioning To IPv6: The Reality

• Interoperability– Network elements

• Clients

• Servers

• Routers

• Gateways

• VoIP networks

• Network management nodes

• Transition nodes

• Firewalls


Transitioning To IPv6: The Reality (cont.)

• Interoperability (cont.)– Software

• Network management and utilities

• Network Internet infrastructure applications

• Network systems applications

• Network end-user applications

• Network high-availability software

• Network security software


Transitioning To IPv6: The Reality (cont.)

• Availability

• What’s next?– Department of Defense (DoD) has committed

to deploying IPv6 by 2008


Chapter Summary

• Adopting the new version of the Internet Protocol, IPv6, would solve the IP address shortage, because IPv6 supports more than 1027 times the number of addresses that IPv4 currently supports

• It also reserves a portion of its address space for use as a globally unique interface identifier, to make it easy to accommodate self-configuring devices and mobile users


Chapter Summary (cont.)

• For backward compatibility, IPv6 defines two mechanisms (IPv4-compatible and IPv4-mapped addresses) whereby IPv4 addresses can work in or interoperate withIPv6 addresses without substantial alteration

• IPv6 also does away with broadcasting by requiring nodes to subscribe to multicasts and using anycast addresses to reach servers or devices that play special networking roles (like routers), thereby eliminating potential waste of bandwidth and routing resources



• Above and beyond vastly increased address space, IPv6 also supports great improvements to communications security, auto-configuration, Quality of Service handling, routing efficiency, and mobile use

• IPv6 builds on lessons learned in IPv4 to streamline headers, allocate and aggregate addresses, and generally improve routing behavior

• Thus, even though the IPv6 address space is enormously larger than the IPv4 address space, most experts believe it will enjoy faster routing behavior (and therefore, better perceived performance) than current IPv4 environments can deliver



• IPv6 introduces a Neighbor Discovery protocol that helps support stateless autoconfiguration and provides improved support for mobile users

• The basic IPv6 packet format has been redesigned to streamline processing time en route to and at its intended destination(s)

• It uses a constant length header and requires options to break on 64-bit boundaries, and various extension headers to speed packet parsing and handling by requiring senders to discover the lowest MTU value (called the Path MTU) for all transmissions, IPv6 also does away with requirements for routers to fragment packets



• Through vastly improved autoconfiguration support for both stateful (like DHCPv6) and stateless methods (available to all requesters on demand), IPv6 makes it easier to renumber networks than with IPv4

• When network numbering schemes match actual network topologies, routing becomes more efficient

• Improved autoconfiguration also permits enhanced mobile access to the Internet as well and enables easy, routine reconfiguration of networks as needed



• IPv6 embeds a robust, built-in security in its required core implementation

• This is a great improvement over IPv4, where security features were added to correct initial design decisions that reflected an overly optimistic security posture

• IPv6 effectively addresses most known security issues in IPv4 by making IP Security (IPSec) mandatory (it’s an optional add-on to IPv4)

• Secure mechanisms for access control, integrity mechanisms, data origin authentication, replay protection, and confidentiality are therefore integral to IPv6 itself



• Mobile IPv6 is the technology whereby IPv6 enables mobile users to operate even though they may move from one location to another

• It addresses key housekeeping details necessary to make user identity mobile and to keep users accessible to the network at the same time



• IPv6 incorporates incremental updates to most core IP protocols, including both IP and TCP

• At the same time, IPv6 remains broadly compatible with IPv4, so that the two can coexist effectively and efficiently for many years

• IPv6 has been designed to permit IPv4 addresses and packets to work within its framework, but also to permit IPv6 traffic to flow through IPv6 networks



• The desire for globally routable addresses (not private or NAT addresses) and the need for new functionality, particularly to keep mobile users in touch with one another and with network and information resources, are the two primary forces that will drive migration to IPv6 over time

• Obstacles to the widespread deployment of IPv6 include IPv4/IPv6 interoperability, availability of IPv6 addresses, complexity of migration, widespread demand for IPv6 advanced features and capabilities, and support from upper management

Guide To TCP/IP, Second Edition

Documents

new ipv6 address space

editionobjectives cont

coexistence of ipv6

creation of ipv6

native ipv6 addresses

enhanced ipv6 features

extension headershop

new version of ip