guide to tcp/ip fourth edition chapter 10: transitioning from ipv4 to ipv6: interoperation
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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 – 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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Basic Hybrid Network Model
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Nested Hybrid Network Model
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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 10-10 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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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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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 10-15 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
© 2013 Course Technology/Cengage Learning. All Rights Reserved.
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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6to4 Components
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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
48© 2013 Course Technology/Cengage Learning. All Rights Reserved.
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
49© 2013 Course Technology/Cengage Learning. All Rights Reserved.
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
50© 2013 Course Technology/Cengage Learning. All Rights Reserved.
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
51© 2013 Course Technology/Cengage Learning. All Rights Reserved.
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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Teredo Components
• Essential components of a Teredo system– Teredo client– Teredo server– Teredo relay,– Teredo host-specific relay
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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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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
© 2013 Course Technology/Cengage Learning. All Rights Reserved.
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