Guide to TCP/IP, Third Edition : Guide to TCP/IP, Third Edition Chapter 13:
Internet Protocol Version 6
Objectives : 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
Objectives (continued) : Internet Protocol Version 6 3 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
Why Create a New Version of IP? : Internet Protocol Version 6 4 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
The IPv6 Address Space : Internet Protocol Version 6 5 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
Address Format and Allocations : Internet Protocol Version 6 6 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
Address Format and Allocations (continued) : Internet Protocol Version 6 7 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
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Address Format and Allocations (continued) : Internet Protocol Version 6 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
Address Types : Internet Protocol Version 6 10 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)
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Address Types (continued) : Internet Protocol Version 6 14 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
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Address Types (continued) : Internet Protocol Version 6 16 Address Types (continued) Link-local address
Has its first 10 (leftmost) bits set to 1111111010
Site-local address
Has its first 10 (leftmost) bits set to 1111111011
IPv6
Pre-allocates only about 15% of its available addresses
Address space set aside for addresses using Network Service Access Point (NSAP) type addressing
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Routing Considerations : Internet Protocol Version 6 19 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
Neighbor Discovery and Router Advertisement : Internet Protocol Version 6 20 Neighbor Discovery and Router Advertisement ND uses five ICMP message types
Router Solicitation (RS)
RouterAdvertisement (RA)
Neighbor Solicitation (NS)
Neighbor Advertisement (NA)
Redirect
Path MTU Discovery and Changes in Fragmentation : Internet Protocol Version 6 21 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
Working with IPv6 Protocols : Internet Protocol Version 6 22 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
Nam Resolution in IPv6 : Internet Protocol Version 6 23 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
IPv6 Packet Formats : Internet Protocol Version 6 24 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
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Basic IPv6 Header Format : Internet Protocol Version 6 26 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
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Extension Headers : Internet Protocol Version 6 28 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
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New and Enhanced IPv6 Features : Internet Protocol Version 6 30 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
Autoconfiguration : Internet Protocol Version 6 31 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
Stateless Autoconfiguration : Internet Protocol Version 6 32 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
Security : Internet Protocol Version 6 33 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
Terms of Encryption : Internet Protocol Version 6 34 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
Quality of Service : Internet Protocol Version 6 35 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
Router Alerts and Hop-by-Hop Options : Internet Protocol Version 6 36 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
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Mobile Users : Internet Protocol Version 6 39 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
Coexistence of IPv4 and IPv6 : Internet Protocol Version 6 40 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
Tunneling Through the IPv4 Cloud : Internet Protocol Version 6 41 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 Rate of Adoption : Internet Protocol Version 6 42 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
Transitioning to IPv6: The Reality : Internet Protocol Version 6 43 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
Interoperability : Internet Protocol Version 6 44 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
Network Elements : Internet Protocol Version 6 45 Network Elements Clients
Servers
Routers
Gateways
VoIP networks
Network management nodes
Transition nodes
Firewalls
Software : Internet Protocol Version 6 46 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
Transitioning to IPv6 from the Windows Perspective : Internet Protocol Version 6 47 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)
Availability : Internet Protocol Version 6 48 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
Summary : Internet Protocol Version 6 49 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
Summary (continued) : Internet Protocol Version 6 50 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
Summary (continued) : Internet Protocol Version 6 51 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