IPV6 Introduction

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IPv6 Introduction

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Introduction to IPv6
 IPv4 has stood the test of time – a tribute to its initial
design
 Proven to be robust
 Easily implemented
 Interoperable
 The initial design did not anticipate today’s Internet scale
and size
 Exhausting IPv4 address space
 Large routing tables
 Simpler management of IPv4 addresses
 Security at IP level
 QoS requirements

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Introduction…
 To address this and other concerns
IETF developed a suite of protocols and
standards
 Internet Protocol version 6 (IPv6)

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Introduction…
 Design of IPv6 is intentionally targeted for minimal
impact on upper and lower layer protocols
http://technet.microsoft.com/en-us/library/bb726993.aspx

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IPv6 Packets and Data Link
Layer
 A link layer frame containing an IPv6 packet consists of
the following structure:
 Link Layer Header and Trailer – The encapsulation
placed on the IPv6 packet at the link layer.
 IPv6 Header – The IPv6 header.
 Payload –The payload of the IPv6 packet.

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IPv6 Features
 New header format
 Large address space
 Efficient and hierarchical addressing and
routing infrastructure
 Stateless and stateful address configuration
 Built-in security
 Better support for prioritized delivery
 New protocol for neighboring node interaction
 Extensibility

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New Header Format
 The IPv6 header keeps header overhead to a
minimum.
 Moves both non-essential fields and optional fields to
extension headers that are placed after the IPv6
header.
 The streamlined IPv6 header is more efficiently
processed at intermediate routers.
 IPv4 headers and IPv6 headers are not interoperable.
 The new IPv6 header is only twice as large as the IPv4
header even though the number of bits in IPv6
addresses is four times larger than IPv4 addresses.

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Large Address Space
 128 bit address space
 Sufficient for growth in the foreseeable
future
 Techniques such as NAT/PAT for
address preservation is not needed

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Efficient and hierarchical addressing
and routing infrastructure
 IPv6 global addresses used on the IPv6
portion of the Internet are designed to
create an efficient, hierarchical, and
summarizable routing infrastructure that is
based on the common occurrence of
multiple levels of Internet service
providers.

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Stateless and stateful address
configuration
 IPv6 supports both stateful address
configuration, such as address
configuration in the presence of a DHCP
server, and stateless address
configuration (address configuration in
the absence of a DHCP server).

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Built-in security
 Support for IPsec is an IPv6 protocol
suite requirement

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Better Support for Prioritized
Delivery
 New fields in the IPv6 header define
how traffic is handled and identified.
 Because the traffic is identified in the
IPv6 header, support for prioritized
delivery can be achieved even when the
packet payload is encrypted with IPsec.

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New Protocol for Neighboring
Node Interaction
 The Neighbor Discovery protocol manage
the interaction of neighboring nodes
(nodes on the same link).
 Neighbor Discovery replaces the
broadcast-based Address Resolution
Protocol (ARP), ICMPv4 Router Discovery,
and ICMPv4 Redirect messages with
efficient multicast and unicast Neighbor
Discovery messages.

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Extensibility
 IPv6 can easily be extended for new
features by adding extension headers
after the IPv6 header.
 Unlike options in the IPv4 header,
which can only support 40 bytes of
options, the size of IPv6 extension
headers is only constrained by the size
of the IPv6 packet.

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IPv4 vs IPv6
IPv4 IPv6
Source and destination addresses are 32 bits (4
bytes) in length.
Source and destination addresses are 128 bits (16
bytes) in length.
IPsec support is optional. IPsec support is required.
No identification of packet flow for QoS handling by
routers is present within the IPv4 header.
Packet flow identification for QoS handling by
routers is included in the IPv6 header using the
Flow Label field
Fragmentation is done by both routers and the
sending host.
Fragmentation is not done by routers, only by the
sending host.
Header includes a checksum. Header does not include a checksum.
Header includes options. All optional data is moved to IPv6 extension
headers.
Address Resolution Protocol (ARP) uses broadcast
ARP Request frames to resolve an IPv4 address to
a link layer address.
ARP Request frames are replaced with multicast
Neighbor Solicitation messages.

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IPv4 vs IPv6

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References
 Windows Server 2008 White Paper –
Introduction to IPv6
Downloadable via -
http://technet.microsoft.com/en-
us/library/bb726944.aspx
http://download.microsoft.com/download/e/
9/b/e9bd20d3-cc8d-4162-aa60-
3aa3abc2b2e9/IPv6.doc

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References (contd.)
 Understanding IPv6, 3rd Edition by
Joseph Davies
 Downloadable as a free e-book