IPv6 Specification RFC - 2460

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IPv6 SpecificationRFC - 2460
11th Sept, 2003

• By Nyi Nyi Thein
• CS-556 Telecom Network II
• Instructor Dr. Kim, Yeongkwun

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Definition

• IPv6 (Internet Protocol Version 6) is the latest
  level of the Internet Protocol and is now
  included as part of IP support in many products
  including the major computer operating systems.
  has also been called "IPng" (IP Next Generation),
  designed as the successor to IP version 4 (IPv4)
  RFC-791.

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IPv6 ( Introduction )

• 32-bit address space means all possible addresses
  will be completely allocated by sometime between
  2008 and 2018.
• Although there is a lot of time left until the
  current address space is exhausted, it will take
  considerable time to deploy a new technology on
  such an extensive scale so it is important to
  start now.

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IETF IPv6

• There are 90 RFCs that describe aspects of IPv6,
  including
• RFC2460 Internet Protocol, Version 6 (IPv6)
  Specification December 1998
• RFC2373 IP Version 6 Addressing Architecture
  July 1998
• RFC3177 IAB/IESG Recommendations on IPv6 Address
  September 2001
• And many more that reference application to IPv6

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IPv6( expanded addressing capability )

• IPv6 increase the size of the IP address from 32
  bit to 128 bit.
• This is enough to allow every grain of sand its
  own IP address. ( Yes! That is a VERY Big number
  !!! )
• Smaller number of header fields
• Altered support for header extensions
• Addition of a flow label header field

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IPv6 Strengths

• Larger Addresses Allows billions of devices to
  be interconnected
• Larger Address pool means no forced Network
  Address Translators in many future deployment
  scenarios
• Eliminate NAT architectures as a means of address
  scaling
• Allow coherent end-to-end packet delivery
• Improve the potential for use of end-to-end
  security tools for encryption and authentication
• Allow for widespread deployment peer-to-peer
  applications
• Users and service providers can update to IPv6
  independently without having to coordinate with
  each other.

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IPv6 (Additional motivation)

• header format helps speed pocessing / forwarding
• Introduce new anycast address allows a
  datagram addressed to an anycast address to be
  delivered to any one of a group hosts.

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IPv6 ( What has not change )

• IPv6 is a connectionless datagram delivery
  service, using end-to-end address identifiers and
  end-to-end signaling, with TCP and UDP transport
  services.

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IPv4 vs IPv6( datagram format)
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Fields defined in IPv6

• Version 4-bit Internet Protocol version number
  6.
• Traffic Class 8-bit traffic class field.
• Flow Label 20-bit flow label.
• Payload Length 16-bit unsigned integer. Length
  of the IPv6 payload, i.e., the rest of the
  packet following this IPv6 header, in
  octets.

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Fields defined in IPv6

• Next Header this 8-bit selector. Identifies the
  type of header immediately following the
  IPv6 header. Uses the same values as the IPv4
  Protocol field
• Hop Limit 8-bit unsigned integer.
  Decremented by 1 by each node that
  forwards the packet. The packet is discarded
  if Hop Limit is decremented to zero.

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Fields defined in IPv6

• Source Address 128-bit address of the
  originator of the packet
• Destination Address 128-bit address of the
  intended recipient of the packet

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IPv6 Header

• A closer look at some of the fields
• Priority identify priority among datagrams
  in flow
• Flow Label identify datagrams in same
  flow. (concept offlow not well
  defined).
• Next header identify upper layer protocol for
  data

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IPv6 Header

• Traffic Class Similar idea to the type of
  service field in IPv4
• Checksum Does not exist in IPv6! It was
  removed entirely to reduce processing time
  at each hop
• Options allowed, but outside of header,
  indicated by Next Header field

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IPv6 datagram format

• fixed-length 40 byte header allows for faster
  processing of the IP datagram. A new encoding of
  options allows for more flexible options
  processing
• no fragmentation/reassembly allowed at
  intermediate router. The operations can be
  performed only by the source and destination.

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New ICMP for IPv6 (ICMPv6)

• used by IP nodes to report error conditions and
  provide limited information
• added new types and codes required by the new
  IPv6 functionality. (e.g. Packet Too Big type
  and unrecognized IPv6 options error code.
• Used to managed a hosts joining and leaving so
  called multicast group management functions

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Terminology

• node - a device that implements IPv6.
• router - a node that forwards IPv6 packets not
  explicitly addressed to itself.
• host - any node that is not a router.
• upper layer - a protocol layer immediately above
  IPv6.
• link - a communication facility or medium over
  which nodes can communicate at the link layer,
  i.e., the layer immediately below IPv6.

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Terminology

• neighbors - nodes attached to the same link.
• interface - a node's attachment to a link.
• address - an IPv6-layer identifier for an
  interface or a set of interfaces.
• packet - an IPv6 header plus payload.
• link MTU - the maximum transmission unit, i.e.,
  maximum packet size in octets, that can be
  conveyed over a link
• path MTU - the minimum link MTU of all the links
  in a path between a source node and a destination
  node.

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Transition From IPv4 To IPv6

• Not all routers can be upgraded simultaneously
• no flag days
• How will the network operate with mixed IPv4 and
  IPv6 routers?

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Transition From IPv4 To IPv6

• Two proposed approaches
• Dual Stack some routers with dual stack (v6,
  v4) can translate between formats
• Tunneling IPv6 carried as payload in IPv4
  datagram among IPv4 routers

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Dual Stack Approach

• IPv6 nodes have full IPv4 capabilities as well.
  When operating with an IPv4 node, the IPv6 node
  uses v4 datagrams. The node will be able to
  determine the capabilities of the node it is
  communicating with by looking at the address
  returned by the DNS.

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Dual Stack Approach

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Tunneling

• Logical View

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Tunneling

• Physical View

B-to-C IPv6 inside IPv4
D-to-E IPv6 inside IPv4
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Expanded Addressing Capabilities

• IPv6 increases the IP address size from 32 bits
  to 128 bits, to support more levels of addressing
  hierarchy, a much greater number of addressable
  nodes, and simpler auto-configuration of
  addresses. The scalability of multicast routing
  is improved by adding a "scope" field to
  multicast addresses. And a new type of address
  called an "anycast address" is defined, used to
  send a packet to any one of a group of nodes.

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Header Format Simplification

• Some IPv4 header fields have been dropped or made
  optional, to reduce the common-case processing
  cost of packet handling and to limit the
  bandwidth cost of the IPv6 header.

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IPv6 Extension Headers

• In IPv6, optional internet-layer information is
  encoded in separate headers that may be placed
  between the IPv6 header and the upper- layer
  header in a packet. There are a small number of
  such extension headers, each identified by a
  distinct Next Header value. As illustrated in
  these examples, an IPv6 packet may carry zero,
  one, or more extension headers, each identified
  by the Next Header field of the preceding header

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Improved Support for Extensions and Options

• Changes in the way IP header options are encoded
  allows for more efficient forwarding, less limits
  on the length of options, and greater flexibility
  for introducing new options in the future.

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Flow Labeling Capability

• A new capability is added to enable the labeling
  of packets belonging to particular traffic
  "flows" for which the sender requests special
  handling, such as non-default quality of service
  or "real-time" service.

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Authentication and Privacy Capabilities

• Extensions to support authentication, data
  integrity, and (optional) data confidentiality
  are specified for IPv6.

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IPv6 Is Ready

• Volume deployment has begun
• Microsoft XP and Server 2003
• Apple MacOS X 10.2
• Linux and BSD
• Sun Solaris
• IBM
• HP
• Symbian OS 7
• Realtime OSs available
• Cisco, Juniper, Hitachi routers support IPv6
• IPv6 is waiting to be turned on!

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IPv6 Transition and Coexistence

• V6 will not take over all data networking
  requirements in a working future time frame (i.e.
  V4 is not disappearing anytime soon)
• About the most likely scenario is a dual stack
  world for some years to come
• Dual stack transitional worlds present many
  complex issues in terms of referential integrity
  of identity, reach ability, gateway
  functionality, security and application
  functionality

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IPv6 (current activities)

• Increasing level of experimentation and trials
  within the ISP provider sector, and some
  commercial services are appearing
• BUT still no overwhelming impetus to immediately
  deploy V6 services in many markets

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IPv6 Myths

• IPv6 is more secure than V4
• Not Really
• IPv6 is no more or less secure than V4. Both IPv6
  and IPv4 offer stronger potential security than
  IP with header architectures simply because the
  original IP source and destination address header
  fields can be included in the packet
  authentication space

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IPv6 Myths

• Only IPv6 supports mobility
• Not Really
• Both V4 and V6 support mobility equally well
• The problem is the overloaded semantic of an IP
  address which duals as identity and network
  location

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IPv6 Vs IPv4

• There is no compelling feature or aspect of V6
  that does not have a functional counterpart in
  V4.
• Any industry adoption of V6 cannot based on
  superior functionality of V6 over V4 as a
  protocol platform
• The fundamental difference is the larger address
  fields used in V6
• But this single difference might well be enough
  to propel V6 adoption in a smart device world

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References

• James F Kurose, Keith W.Ross (Computer
  Networking, A top down approach featuring the
  Internet )
• RFC 2460 fount at (http//www.ietf.org/rfc/2460)
• IPv6 Specification found at (http//www.potaroo.ne
  t)

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• Thank You !!!

Internet Protocol Version 6 Specification
(IPv6) RFC - 2460