guide to tcp/ip fourth edition chapter 10: transitioning from ipv4 to ipv6: interoperation

Guide to TCP/IP Fourth Edition

Chapter 10:

Transitioning from IPv4 to IPv6: Interoperation

2

Objectives

• Describe the various methods that allow IPv4 and IPv6 networks to interact, including dual stack and tunneling through the IPv4 cloud

• Explain hybrid IPv4/IPv6 network and node types, such as basic hybrid, nested hybrid, and true hybrid

• Explain how an IPv6 transition address works

• Describe the various IPv4/IPv6 transition mechanisms, such as dual stacks and IPv6-over-IPv4 tunneling

© 2013 Course Technology/Cengage Learning. All Rights Reserved.

3

Objectives (cont'd.)

• Describe the different tunneling configuration types and their device interactions

• Explain the ISATAP tunneling mechanism, including its components, addressing, and routing and router configuration

• Explain the 6to4 tunneling mechanism, including its components, addressing and routing, and communication procedures

• Explain the Teredo tunneling system, including its components, addressing and routing, and processes


4

How Can IPv4 and IPv6 Interact?

• IPv6 and IPv4 will probably exist side by side for many years

• Designers of IPv6 anticipated a slow cutover– Created a set of techniques to allow IPv6 to function

adequately in a world dominated by IPv4


5

Dual-Stack Approach

• Dual-stack – Implementations for individuals or small offices may

work as experiments• However, they 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


6

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

• IPv6 packet is formed normally– Sent to a router capable of encapsulating it in an

IPv4 packet

• 6to4 tunneling method– Alternate scheme specified in RFC 3056


7

IPv6 Rate of Adoption

• Biggest push for the adoption of IPv6 – Coming from those who were not a part of the initial

Internet “land rush” of the 1990s

• Makers of technologies (cellular phones and smartphones) have two reasons to embrace IPv6– They want the address space– Communications technologies need the improved

functionality of the IPv6 protocol suite


8

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


9

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


10

Network Elements

• Network elements and software tools– Clients– Servers– Routers– Gateways– VoIP networks– Network management nodes– Transition nodes– Firewalls


11

Software

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


12

Transitioning to IPv6 from the Windows Perspective

• Microsoft provides support for IPv6 implementations for: – Windows Server 2008– Windows Vista– Windows 7

• Microsoft – Supports the Intra-Site Automatic Tunnel Addressing

Protocol (ISATAP)


13

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


14

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


15

What’s Next?

• Major obstacle– Convincing executive managers to deploy an IPv6

solution

• Major event that may accelerate the deployment of IPv6– Announcement that the Department of Defense

(DoD) will be IPv6 ready by 2012


16

Hybrid IPv4/IPv6 Networks and Node Types

• As software and hardware components are upgraded– IPv6 devices will need to be able to talk to each

other over an IPv4 infrastructure

• “Mixed” environments are called hybrid networks


Basic Hybrid Network Model

17© 2013 Course Technology/Cengage Learning. All Rights Reserved.

Nested Hybrid Network Model


True Hybrid Network Model


20

IPv6 Transition Addresses

• IP address parser– Attempts to translate an IPv4 address into its IPv6

equivalent

• Transition address methods– Using literal IPv6 addresses in URLs– Stateless IP/ICMP translation algorithm (SIIT)


21

Transition Mechanisms

• Methods and address types that provide for communication between network nodes– That use only IPv4 or only IPv6 to interact with each

other or with network resources

• Transition from IPv4 to IPv6 requires multiple stages


22

Dual Protocol Stacks for IPv4 and IPv6

• Implemented at the level of the device’s operating system

• Dual-stack implementations use special addressing

• Most modern operating systems have IPv6 enabled by default

• Dual stack and dual layer– Different types of architecture


23

Dual-IP-Layer Architecture

• Has both IPv4 and IPv6 protocols operating in a single Transport layer implementation


24

Dual-IP-Layer Architecture (cont’d.)


25

Dual-Stack Architecture

• Maintains separate stacks at both the Network and Transport layers


26

Dual-Stack Architecture (cont’d.)


27

Dual Architecture and Tunneling

• Dual-architecture nodes– Can produce either IPv4 or IPv6 packets and

forward them to a gateway router– Need two network interfaces, one for IPv4 and the

other for IPv6


28

IPv6-over-IPv4 Tunneling

• Used to allow IPv6 network nodes to send packets over an IPv4 network infrastructure

• Presents a challenge for IPv6 header construction

• Source node determines which packets must be encapsulated– Based on the routing information the node maintains

in its own routing table


29

IPv6-over-IPv4 Tunneling (cont’d.)


30

DNS Infrastructure

• DNS records and DNS name resolution management– Handled differently for IPv4 and IPv6

• DNS servers must be configured for dual stack– Supporting both A and AAAA records

• In mixed IPv4/IPv6 environments– DNS resolver libraries on network nodes must have

the ability to manage both A and AAAA records


31

Tunneling Configurations for Mingling IPv4 and IPv6

• Tunneling mechanism configurations– Defined by RFC 4213

• Encapsulator– Node at the sending end of the tunnel

• Decapsulator– Receiving node at the other end of the tunnel


32

Router-to-Router

• Requires specifically configured end points to the tunnel


33

Host-to-Router and Router-to-Host

• Represents the first and last legs of a packet’s trip from source to destination

Figure 10-10 Host-to-router and router-to-host tunnels


34

Host-to-Host

• Two IPv6 nodes are linked directly using a tunnel over an IPv4 network infrastructure


35

Types of Tunnels

• RFC 2893 originally specified two different tunneling types– Configured and automatic

• RFC 4213, which made RFC 2893 obsolete– Removed references to automatic tunneling

• Configured tunnels– Require that end point addresses be determined in

the encapsulator device• From configuration data stored for each tunnel


36

ISATAP

• Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)– Used to connect dual-stack IPv4/IPv6 devices

across IPv4 network infrastructures

• Routing and Addressing in Networks with Global Enterprise Recursion (RANGER)– Builds on ISATAP to include IPv6 autoconfiguration


37

Overview

• Implements router-to-host, host-to-router, and host-to-host address assignments

• Supported on Windows Vista, Windows 7, Windows Server 2003, and Windows Server 2008

• ISATAP IPv6 automatic tunneling– Can be used in domains that adhere to security

specifications found in RFC 5214

• ISATAP nodes– Must observe functionality requirements for IPv6

computers found in RFC 4294


ISATAP Components


39

Router Discovery for ISATAP Nodes

• ISATAP interfaces– Use neighbor discovery mechanisms described in

RFC 4861

• Because of the lack of multicast support– Automatic router discovery cannot be used

• ISATAP hosts use PRLs to maintain current information about ISATAP routers


40

ISATAP Addressing and Routing

• ISATAP addresses use the locally administered interface identifier

• Windows 7 or Windows Server 2008 computers– Are automatically assigned ISATAP addresses

• Each device involved in communicating on or off an ISATAP network– Uses different routes to direct traffic from source to

destination nodes

• Devices and routers from other subnets need routes to send traffic to the ISATAP logical subnet


ISATAP Addressing and Routing (cont’d.)


42

ISATAP Communications

• ISATAP node uses host-to-host tunneling

• ISATAP host communicating with an IPv6 node on an IPv6-capable subnet involves two different connections– Host-to-router tunnel– Connection between ISATAP router and IPv6-

capable subnet


43

Configuring an ISATAP Router

• Windows Vista/7/Server 2008 computers– Can be configured as ISATAP routers

• ISATAP configuration is performed at the command prompt


44

Configuring an ISATAP Router (cont’d.)

• Insert Figure 10-15 here (image quality is really poor)


45

6to4

• IPv4-to-IPv6 transition technology – Allows IPv6 packets to be sent across IPv4 network

infrastructures, including the IPv4 Internet– RFC 3056, current documentation

• Assigns an interim and unique IPv6 address prefix to any site that already possesses IPv4 addresses

• Specifies encapsulation method for sending IPv6 packets over IPv4 using the unique prefix address


Overview

• Avoids the need to configure the distinct tunnels required by ISATAP

• Applied to a network node or to a local network

• 6to4 addressing on an IPv6 network employs autoconfiguration– Uses the last 64 bits as the host address and the

first 64 bits as the IPv6 prefix

• 6to4 issues– Large numbers of misconfigured nodes– Poor network performance


6to4 Components


6to4 Addressing and Routing

• Any 6to4 site must possess at least one valid globally unique 32-bit IPv4 address

• 6to4 gateway router directly attached to the Internet– Receives an IPv4 address assignment from a

service provider– Address represents the site address

• 6to4 network devices use on-link and default routes

• 6to4 relay uses on-link route on its tunneling interface to perform router-to-router communication


6to4 Communication

• Communication models in a 6to4 infrastructure– Node-to-node/router – Node-to-node

• Communication between 6to4 node and IPv6 host must go– From sending node to router– From router to relay– From relay to receiving node


Using ISATAP and 6to4 Together

• Normally, an ISATAP host could not receive advertisements from a 6to4 router– 6to4 router could also be manually configured as an

ISATAP router

• ISATAP node then configures a default route to the 6to4 router in order to send traffic


Teredo

• IPv4-to-IPv6 transition technology– Allows IPv6 connections between two IPv6 network

nodes across an IPv4 network infrastructure

• Can operate from behind home routers and broadband devices– Using network address translation (NAT)

• Developed by Microsoft– Formally standardized by RFC 4380


Overview

• Teredo service tunnels IPv6 packets over IPv4 UDP– Using Teredo servers and Teredo relays

• Teredo servers are stateless– Responsible for managing only small amounts of

traffic between Teredo client computers

• Teredo relays– Perform IPv6 routing between the Teredo service

and IPv6-capable networks


Teredo Components

• Essential components of a Teredo system– Teredo client– Teredo server– Teredo relay,– Teredo host-specific relay


Teredo Addressing and Routing

• Teredo addresses are made up of five components:– Prefix– Server IPv4– Flags– Port– Client IPv4

• Like other IPv4/IPv6 transition mechanisms– Teredo uses online and default routes


Teredo Processes


56

Summary

• During the transition from IPv4 to IPv6, there will be a lengthy period of time when both protocols exist side by side

• Several different IPv4/IPv6 hybrid networks and nodes can be used to facilitate the transition

• Transition mechanisms can use a dual-IP-layer architecture or a dual-stack architecture

• IPv6-over-IPv4 tunneling involves different device configurations


57

Summary (cont'd.)

• ISATAP is an automatic tunneling mechanism that allows IPv6 ISATAP network nodes to communicate across an IPv4 network

• 6to4 is an IPv4-to-IPv6 transition technology characterized by its ability to allow IPv6 packets to be sent across IPv4 networks and the use of relay servers

• Teredo is another IPv4-to-IPv6 transition technology characterized by its unique ability to operate behind routers and broadband devices with NAT enabled


guide to tcp/ip fourth edition chapter 10: transitioning from ipv4 to ipv6: interoperation

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