IPv6

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Many of the finest developers and engineering minds have been working on IPv6 since the early 1990s. Hundreds of RFCs have been written and have detailed some major areas, including expanded addressing, simplified header format, flow labeling, authentication, and privacy. Expanded addressing moves us from 32-bit address to a 128-bit addressing method. It also provides newer unicast and addressing methods, injects hexadecimal into the IP address, and moves from using "." to using ":" as delimiters.
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<meta name="keywords" content="ipv6, internetworking"></meta>
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This IP Version 6 information is intended for network professionals with good IP version 4 (IPv4) networking skills and knowledge. It is ideal for anyone, including account managers and system engineers, who is required to analyze IPv6 network requirements and develop strategies for the deployment of IPv6 networks. In addition to the content listed in the Resources and References section, you can also find information on IPv6 implementation details including the roadmap, software configuration, and Statement of Direction at http://www.cisco.com/go/ipv6.
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== Introduction: Rationale for a New Version of IP ==
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[[IPv6#Figure: IPv6 Packet Header Format|Figure: IPv6 Packet Header Format]] shows the IPv6 packet header format.
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IP version 6 is a new IP protocol designed to replace IP version 4, the Internet protocol that is predominantly deployed and extensively used throughout the world. IPv4 has proven to be robust, easily implemented, and interoperable, and has stood the test of scaling an internetwork to a global utility the size of the Internet today. However, the initial design did not anticipate the following conditions:
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=====Figure: IPv6 Packet Header Format=====
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*Exponential growth of the Internet and the impending exhaustion of the IPv4 address space
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*Ability of Internet backbone routers to maintain large routing tables
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*Need for simpler autoconfiguration and renumbering
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*Requirement for security at the IP level
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*Need for better support for real-time delivery of data
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[[image:CT843201.jpg]]
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== Evolution of Internet Protocol Version 6 ==
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== Description of IPv6 Packet Header ==
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The original proposal for IPv6 proposed is in RFC 1752, The Recommendation for the IP Next Generation Protocol was the Simple Internet Protocol Plus (SIPP) with a larger (128 bit) address space. Following that proposal, the IETF started a working group and the first specification came in late 1995 with RFC 1883, Internet Protocol, Version 6 (IPv6) Specification. RFC 2460, Internet Protocol, Version 6 (IPv6) Specification obsoletes RFC 1883 and is the present standard for IPv6.  
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The simplified header is 40 bits long and the format consists of Version, Class, Flow Label, Payload Length, Next Header, Hop Limit, Source Address, Destination Address, Data, and Payload fields.
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== Hexadecimal "Hex" ==
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At its simplest, hex numbers are base 16. Decimal is base 10, counting from 0 to 9, as we do in decimal, and then adding a column to make 10. Counting in hex goes from 0 to F before adding a column.  
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The characters A through F represent the decimal values of 10 through 15, as illustrated in [[IPv6#Figure: Hex Characters A Through F Represent the Numbers 10 Through 15|Figure: Hex Characters A Through F Represent the Numbers 10 Through 15]].
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IPv6 quadruples the number of network address bits from 32 bits (in IPv4) to 128 bits, which provides more than enough globally unique IP addresses for every network device on the planet. The use of globally unique IPv6 addresses simplifies the mechanisms used for reachability and end-to-end security for network devices, functionality that is crucial to the applications and services that are driving the demand for the addresses.
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=====Figure: Hex Characters A Through F Represent the Numbers 10 Through 15=====
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== Features and Benefits of Using IPv6 ==
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[[image:CT843202.jpg]]
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In addition to meeting the anticipated future demand for globally unique IP addresses, IPv6 provides the following benefits:  
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Counting in hex goes as follows: 0 1 2 3 4 5 6 7 8 9 A B C D E F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 and up, as far as you want to go.
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*Larger address space for global reachability and scalability
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== Addressing Description ==
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*Simplified header format for efficient packet handling
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Let's look at an example of IPv6 address. The address is an eight-part hex address separated by colons (''':'''). Each part '''n''' can equal a 16-bit number and is eight parts long, providing a 128-bit address length (16 &#42; 8 = 128),
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*Hierarchical network architecture for routing efficiency
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*Support for widely deployed routing protocols
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*Autoconfiguration and plug-and-play support
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*Enhanced support for Mobile IP and Mobile Computing Devices
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*Increased number of multicast addresses
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Addresses are n:n:n:n:n:n:n:n n &#61; 4 digit hexadecimal integer, 16 &#42; 8 &#61; 128 address.
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Details and figures the describe IPv6 formats, simplified packet header, address types, as well as additional information is available at: http://www.cisco.com/web/solutions/netsys/ipv6/knowledgebase/index.html
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<br>'''1080:0:0:0:8:800:200C:417A Unicast address'''
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<br>'''FF01:0:0:0:0:0:0:101 Multicast address'''
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== Addressing Methods ==
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Included in IPv6 are a number of methods:
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* Unicast
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* Multicast
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* Anycast
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Note that there is no explicit notion of "broadcast" in IPv6.
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=== Unicast ===
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Unicast is a communication between a single host and a single receiver. Packets sent to  a unicast address are delivered to the interface identified by that address, as seen in [[IPv6#Figure: Unicast Sends Packets to a Specified Interface|Figure: Unicast Sends Packets to a Specified Interface]].
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=====Figure: Unicast Sends Packets to a Specified Interface=====
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[[image:CT843203.jpg]]
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=== Multicast ===
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Multicast is communication between a single host and multiple receivers. Packets are sent to all interfaces identified by that address, as seen in [[IPv6#Figure: Multicast Sends Packets to a Subnet, and Defined Devices Listen for Multicast Packets|Figure: Multicast Sends Packets to a Subnet, and Defined Devices Listen for Multicast Packets]].
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=====Figure: Multicast Sends Packets to a Subnet, and Defined Devices Listen for Multicast Packets=====
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[[image:CT843204.jpg]]
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=== Anycast ===
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Packets sent to an anycast address or list of addresses are delivered to the nearest interface identified by that address. Anycast is a communication between a single sender and a list of addresses, as shown in [[IPv6#Figure: Anycast Sends Packets to Specified Interface List and Can Contain End Nodes and Routers|Figure: Anycast Sends Packets to Specified Interface List and Can Contain End Nodes and Routers]].
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=====Figure: Anycast Sends Packets to Specified Interface List and Can Contain End Nodes and Routers=====
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[[image:CT843205.jpg]]
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== Summary ==
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Some of the benefits of IPv6 seem obvious: greater addressing space, built-in QoS, and better routing performance and services. However, a number of barriers must be overcome before the implementation of IPv6. The biggest question for most of us will be what the business need is for moving from current IPv4 to IPv6. The killer app has not appeared yet, but it may be closer than we think. The second consideration is the cost-it may not have much to do with hardware replacement cost. All the larger routers have upgradable OSs IOS; the only necessity is the commitment to upgrading IOS. More likely to do with training and support of minor IP devices such as printers and network faxes, they will support the new address space. IPv6 has schemes to support old and new, however, so this may not even be a barrier. The last issue to consider is training: This will need to happen sooner or later because we all need to start thinking about 128-bit addressing based on MAC addresses in HEX. This involves all new ways of addressing and will be an uncomfortable change for many people.
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This conclusion may seem negative, but the greater good will overpower all the up-front issues. The issue is not whether you will have to move to IPv6, but when! We all need IPv6; the increased address space is needed for the growth of IP appliances that we are starting to hear about weekly. IP-ready cars are already shipping today. This requires mobility, which is addressed in IPv6.
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Of course, a number of very important features have not been discussed in this section, including QoS, mobile IP, autoconfiguration, and security. All these areas are extremely important, and until IPv6 is finished, you should keep referring to the IETF Web site for the most current information. Several new books on IPv6 also are starting to show up on bookstore shelves and should provide the deeper technical detail on address headers and full packet details.
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== Review Questions ==
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'''Q''' - ''What is the main reason for IPv6 being developed?''
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'''A''' - The main issue surrounding IPv6 is addressing, or the lack of addressing. Many people believe that we are nearly out of the four billion addresses available in IPv4. IPv6 could be the solution to many problems, but IPv6 is still not fully developed and is not yet a standard.
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'''Q''' - ''How many bits does the new expanded addressing provide?''
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'''A''' - The expanded addressing moves us from 32-bit address to a 128-bit addressing method.
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'''Q''' - ''What other benefits does expanded addressing provide?''
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'''A''' - It provides newer unicast and addressing methods. Expanded addressing also injects hexadecimal into the IP address and moves from using '''.''' to using ''':''' as delimiters.
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'''Q''' - ''What are the new addressing methods included in IPv6?''
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'''A''' - Unicast, multicast, and anycast.
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'''Q''' - ''What is unicast?''
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'''A''' - Unicast is a communication between a single host and a single receiver.
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'''Q''' - ''What is multicast?''
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'''A''' - Multicast is communication between a single host and multiple receivers.
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'''Q''' - ''What is anycast?''
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'''A''' - Anycast is a communication between a single sender and a list of addresses.
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== For More Information ==
== For More Information ==
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*[http://www.cisco.com/web/solutions/netsys/ipv6/knowledgebase/index.html Cisco IPv6 Knowledge Base Portal]
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http://www.cisco.com/web/solutions/netsys/ipv6/index.html
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*[http://www.cisco.com/web/solutions/trends/ipv6/index.html IPv6 - Cisco Systems]<br>
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*[http://supportforums.cisco.com/community/netpro/network-infrastructure/ipv6-transition Cisco Support Community: IPv6 Integration and Testing]
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http://www.cisco.com/web/solutions/netsys/ipv6/knowledgebase/index.html
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*[http://docwiki.cisco.com/wiki/Category:IPv6 IPv6 on DocWiki]
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*[http://en.wikipedia.org/wiki/Ipv6 Wikipedia: IPv6]
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http://www.ietf.org/html.charters/ipngwg-charter.html
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http://www-6bone.lbl.gov/6bone
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http://playground.Sun.COM:80/pub/ipng/html
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[[Category:IOS Technology Handbook]]
[[Category:IOS Technology Handbook]]
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[[Category: IPv6]]

Latest revision as of 20:50, 16 October 2012

Contents

Introduction: Rationale for a New Version of IP

IP version 6 is a new IP protocol designed to replace IP version 4, the Internet protocol that is predominantly deployed and extensively used throughout the world. IPv4 has proven to be robust, easily implemented, and interoperable, and has stood the test of scaling an internetwork to a global utility the size of the Internet today. However, the initial design did not anticipate the following conditions:

  • Exponential growth of the Internet and the impending exhaustion of the IPv4 address space
  • Ability of Internet backbone routers to maintain large routing tables
  • Need for simpler autoconfiguration and renumbering
  • Requirement for security at the IP level
  • Need for better support for real-time delivery of data

Evolution of Internet Protocol Version 6

The original proposal for IPv6 proposed is in RFC 1752, The Recommendation for the IP Next Generation Protocol was the Simple Internet Protocol Plus (SIPP) with a larger (128 bit) address space. Following that proposal, the IETF started a working group and the first specification came in late 1995 with RFC 1883, Internet Protocol, Version 6 (IPv6) Specification. RFC 2460, Internet Protocol, Version 6 (IPv6) Specification obsoletes RFC 1883 and is the present standard for IPv6.

IPv6 quadruples the number of network address bits from 32 bits (in IPv4) to 128 bits, which provides more than enough globally unique IP addresses for every network device on the planet. The use of globally unique IPv6 addresses simplifies the mechanisms used for reachability and end-to-end security for network devices, functionality that is crucial to the applications and services that are driving the demand for the addresses.

Features and Benefits of Using IPv6

In addition to meeting the anticipated future demand for globally unique IP addresses, IPv6 provides the following benefits:

  • Larger address space for global reachability and scalability
  • Simplified header format for efficient packet handling
  • Hierarchical network architecture for routing efficiency
  • Support for widely deployed routing protocols
  • Autoconfiguration and plug-and-play support
  • Enhanced support for Mobile IP and Mobile Computing Devices
  • Increased number of multicast addresses

Details and figures the describe IPv6 formats, simplified packet header, address types, as well as additional information is available at: http://www.cisco.com/web/solutions/netsys/ipv6/knowledgebase/index.html

For More Information

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