IPV6
Features of IPv6
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New header format
Large address space
More efficient routing
IPsec header support required
Simple automatic configuration
New protocol for neighboring node interaction
Extensibility
The IPv6 Address Space
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The most obvious distinguishing feature of Internet
Protocol version 6 (IPv6) is its use of much larger
addresses.
The size of an address in IPv6 is 128 bits, a bit-string
that is four times longer than the 32-bit IPv4 address.
A 32-bit address space allows for 232 or 4,294,967,296,
possible addresses.
A 128-bit address space allows for 2128 or
340,282,366,920,938,463,463, 374,607,431,768,211,456
(3.4 × 1038), possible addresses.
Preferred IPv6 Address Representation
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The preferred representation, also known as the
complete form of an IPv6 address, has a series
of eight 16-bit hexadecimal fields separated
by colons (:).
Each 16-bit field is textually represented by four
hexadecimal characters
Preferred IPv6 Address Representation
IPv6 Address Syntax
• Dotted-Decimal Notation– was convenient for IPv4 addresses,
• Colon Hexadecimal Notation – 128 bits divided into 8 sections of 2
bytes, with each 2 bytes represented in hexadecimal notation
2001:0DB8:0000:2F3B:02AA:00FF:FE28:9C5A
The 16-bit binary equivalent is:
0010000000000001
0000000000000000
0000001010101010
1111111000101000
0000110110111000
0010111100111011
0000000011111111
1001110001011010
Rule 1
To make life easier, some abbreviations are
possible. For instance, leading zeros in a 16-bit
block can be skipped. The example address
now looks like this:
2001:0DB8:0000:2F3B:02AA:00FF:FE28:9C5A
2001:DB8:0:2F3B:2AA:FF:FE28:9C5A
Rule 2
A double colon can replace consecutive zeros or
leading or trailing zeros within the address. For
example:
2001:0DB8:0000:0000:0202:B3FF:FE1E:8329
2001:DB8::202:B3FF:FE1E:8329
BUT you can only apply this once
Rule 2
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This type of abbreviation is allowed only
once per address
If there are two runs of zero sections, only
one of them can be compressed
IPv4 and IPv6
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In environments where IPv4 and IPv6 nodes are
mixed, another convenient form of IPv6 address
notation is to put the values of an IPv4 address
into the four low-order byte pieces of the
address.
An IPv4 address of 192.168.0.2 can be
represented as x:x:x:x:x:x:192.168.0.2, and an
address of 0:0:0:0:0:0:192.168.0.2 can be
written as ::192.168.0.2.
If you prefer, you can also write ::C0A8:2.
IPv6 Address with an Embedded IPv4 Address
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The first part of the IPv6 address uses the hexadecimal
representation, and the IPv4 address part is in decimal
format.
This is a specific representation of an IPv6 address used
by transition mechanisms.
IPv6 Address with an Embedded IPv4 Address
Two kinds of IPv6 addresses have an embedded IPv4
address:
 IPv4-compatible IPv6 address—Used to establish an
automatic tunnel to carry IPv6 packets over IPv4
networks. This address is related to a transition
mechanism of the IPv6 protocol.
 IPv4-mapped IPv6 address—Used only on the local
scope of nodes having both IPv4 and IPv6 stacks.
Nodes use IPv4-mapped IPv6 addresses internally only.
These addresses are never known outside the node
itself and should not go on the wire as IPv6 addresses.
IPv6 Address with an Embedded IPv4 Address
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The IPv6 prefix for the IPv4-compatible IPv6 address is
represented by the high-order 96-bit set to 0 followed by
the 32-bit of the IPv4 address.
0000:0000:0000:0000:0000:0000:206.123.31.2
::206.123.31.2
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The prefix for the IPv4-mapped IPv6 address is
represented by the high-order 80-bit set to 0, then the
next 16-bit set to 1, and finally followed by the 32-bit of
the IPv4 address of the local node.
0000:0000:0000:0000:0000:FFFF:206.123.31.2
::FFFF:206.123.31.2
IPv6 Address with an Embedded IPv4 Address
IPv4-compatible
IPv4-mapped
CIDR Notation
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Just like IPv4 addresses, IPv6 addresses consist of
NetworkID and HostID
IPv6 uses classless notation to identify each of them
Although IPv6 addresses are in hexadecimal format, the
network mask value is still a decimal value.
Network ID is also referred to as prefix, and the number
of bits allocated to Network ID as prefix length
Host ID is referred to as Interface ID
CIDR notation
The default Net and Host IDs are:
The IPv6 Interface ID and EUI-64 Format
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The host portion of an IPv4 address is not based on the
hardware address of an interface.
The interface ID in IPv6 is based on the interface’s
hardware address.
This interface ID adheres to the IEEE 64-bit Extended
Unique Identifier (EUI-64) format. Since most interfaces
still use the 48-bit MAC address, the MAC must be
converted into the EUI-64 format.
Converting the MAC address into the Interface ID
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The first 24 bits of the MAC address identifies the
manufacturer. The last 24 bits uniquely identify the host.
To convert this to EUI-64 format:
1. The first 24 bits of the MAC (the OUI), become the
first 24 bits of the EUI-64 formatted interface ID.
2. The seventh bit of the OUI is changed from a “0” to a
“1”.
3. The next 16 bits of the interface ID are FFFE.
4. The last 24 bits of the MAC (the host ID), become
the last 24 bits of the interface ID.
Converting the MAC address into the Interface ID
IPv6 Address Types
As shown in the following figure, the three types of
addresses are:
 Unicast
 Anycast
 Multicast
Under the scope of each kind of address are one
or more types of addresses.
IPv6 Address Types
Anycast Address
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Unicast is a method used by a source node to send
a packet to one destination (one-to-one)
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Multicast is used for one-to-many communication
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Anycast is used for one-to-nearest communication
Anycast Address
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Anycast is a mechanism that delivers a packet
sent to an anycast address of the nearest node
member of the anycast group.
Anycast enables a type of discovery mechanism
to the nearest point. The network itself plays the
key role in anycast by routing the packet to the
nearest destination by measuring network
distance.
Loopback address
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Similar to the IPv4 protocol, each device has one
loopback address, which is used by the node itself.
The loopback address is represented by the prefix
0000:0000:0000:0000:0000:0000:0000:0001
And by ::1 in the compressed representation
In comparison, the loopback address in IPv4 is
127.0.0.1.
Loopback address
Unspecified address
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An unspecified address is a unicast address not assigned to
any interface.
It indicates the absence of an address and is used for
special purposes. For example, when a host requests an
IPv6 address from a Dynamic Host Configuration Protocol
for IPv6 (DHCPv6) server
The unspecified address is represented by the prefix
0000:0000:0000:0000:0000:0000:0000:0000
in preferred format and by :: in the compressed representation
Unspecified address