1. 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
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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
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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
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5. Dual-Stack Approach Dual-stack Most important dual stack machines
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
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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
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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
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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
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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
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10. Network Elements Network elements and software tools Clients Servers
Routers
Gateways
VoIP networks
Network management nodes
Transition nodes
Firewalls
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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
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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)
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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
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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
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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
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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
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17. Basic Hybrid Network Model
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18. Nested Hybrid Network Model
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19. True Hybrid Network Model
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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)
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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
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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
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23. Dual-IP-Layer Architecture
Has both IPv4 and IPv6 protocols operating in a single Transport layer implementation
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24. Dual-IP-Layer Architecture (cont’d.)
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25. Dual-Stack Architecture
Maintains separate stacks at both the Network and Transport layers
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26. Dual-Stack Architecture (cont’d.)
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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
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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
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29. IPv6-over-IPv4 Tunneling (cont’d.)
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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
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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
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32. Router-to-Router
Requires specifically configured end points to the tunnel
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33. Host-to-Router and Router-to-Host
Represents the first and last legs of a packet’s trip from source to destination
Figure Host-to-router and router-to-host tunnels
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34. Host-to-Host
Two IPv6 nodes are linked directly using a tunnel over an IPv4 network infrastructure
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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
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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
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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
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38. ISATAP Components
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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
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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
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41. ISATAP Addressing and Routing (cont’d.)
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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
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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
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44. Configuring an ISATAP Router (cont’d.)
Insert Figure here (image quality is really poor)
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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
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46. 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
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47. 6to4 Components
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48. 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
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49. 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
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50. 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
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51. 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
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52. 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
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53. Teredo Components Essential components of a Teredo system
Teredo client
Teredo server
Teredo relay,
Teredo host-specific relay
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54. 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
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55. Teredo Processes
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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
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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
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