Lesson 3: IPv6 Fundamentals

 IPv4
 4.3 billion unique addresses
 IPv6
 3.4 undecillion (3.4 ×10³⁸)
 340,282,366,920,938,463,463,374,607,431,768,
211,456
 340 undecillion, 282 decillion, 366 nonillion,
920 octillion, 938 septillion, 463 sextillion, 463
quintillion, 374 quadrillion, 607 trillion, 431
billion, 768 million, 211 thousand, 456

 The limitations of IPv4 are:
 Limited number of addresses
 Routing difficult to manage
 Host configuration is complex
 No built in security
 Limited Quality of Service

 Improvements in IPv6 include:
 Built in QoS (Quality Of Service)
 More efficient routing
 Simpler host configuration
 Better prioritized delivery support
 Redesigned headers for efficient processing and
extensibility
 Built-in security
▪ IP security through the use of IPSec is an integral part of
IPv6, whereas it was an optional feature under IPv4.
 Increased address space
▪ providing 2128 (about 340 billion) unique addresses.

 The IPv6 address space is:
 128 bits address, or 16 bytes for addressing of
four hexadecimal digits, separated by colons
 8 groups of 4 Hex characters
▪ using eight groups Displayed in hexadecimal
▪ Characters: 0-9, A-F
 Allows routing flexibility

 An example of an IPv4 IP address
 192 .168.1.101
 An example of an IPv6 IP address
 2001:0DB8:85A3:08D3:1319:8A2E:0370:7334
 3FFE:0501:0008: 0000:0260: 97FF:FE40:EFAB
▪ 3FFE:501:8:0:260:97FF:FE40:EFAB
▪ 3FFE:501:8::260:97FF:FE40:EFAB

Decimal 0 1 2 3 4 5 6 7
Hex 0 1 2 3 4 5 6 7
Binary 0000 0001 0010 0011 0100 0101 0110 0111

Decimal 8 9 10 11 12 13 14 15
Hex 8 9 A B C D E F
Binary 1000 1001 1010 1011 1100 1101 1110 1111

 IPv6 addresses are:
 Can use zero compression
▪ Eliminate consecutive zeros “: :”
▪ “Leading”
 Use a prefix to define the network portion of
address rather than a subnet mask.
 Two Parts
▪ 64 bit network component
▪ 64 bit host component

 :0: stands for :0000:
 You can omit preceding 0s in any 16-bit word.
 :DB8: and :0DB8: are equivalent.
 A series of sequential zeroes the address can be
shortened to use a single zero in each group, or
else the entire grouping can be represented using
a double colon (: :).
 2001:0000:0000:0000:0000:0000:0000:7334
= 2001:0:0:0:0:0:0:7334 = 2001::7334
 :: can be used only once in an address
 IPv6 Loopback Is ::1

 The address
 2001:0DB8:0000:0000:1234:0000:A9FE:133E
 Compress :0000: into :0:
 2001:0DB8:0000:0000:1234:0:A9FE:133E
 Eliminate preceding zeros:
 2001:DB8:0000:0000:1234:0:A9FE:133E
 Use the special variable shortcut for
multiple 0s:
 2001:DB8::1234:0:A9FE:133E

 Do you subnet IPv6?
 If you are given 32 bits of network from your ISP,
you have 96 bits to work with.
 If you use some of the 96 bits to route within your
network infrastructure, then you are subnetting.
 Client Configuration
 Manual
▪ Required for routers
 Automatically
▪ From routers
▪ DHCPv6 servers

 There are three types of addresses in IPv6:

Type Description
Anycast Equivalent to IPv4 unicast
Unicast Additional unicast address types
Multicast Equivalent to IPv4 multicast

 Anycast
 Visually similar to global
 Many destination hosts with the same address
▪ Address assigned to multiple devices.
 Finds nearest based on router cost
▪ When an anycast packet is sent, it is delivered to one
of the devices, usually the closest one.

 Unicast
 A unicast packet uniquely identifies an interface
of an IPv6 device.
 Unicast addresses come in several types:
▪ Global unicast address
▪ Link-Local Address
▪ Unique Local Address

 Global Addresses (GAs)
 Equivalent of public addresses in IPv4.
 Address space is defined as 2000::/3
▪ High level bits 001
▪ First block value between 2000-3FFF

 Link-Local Address (LLAs)
 Similar to APIPA addresses
 Self-configured, non-routable
 Provides automatic communication on local
subnet
 Defined as FE80:: /10.

 FE80+54 bits “0” +64 bits
▪ The last 8 bytes (64 bits) are random
 Extended User Interface 64-bit (EUI-64) format
▪ MAC-FFFE-MAC
▪ MAC 00044 B 18 EE6C =0004:4BFF:FE18:EE6C
 Always get link-local, even with DHCP

 Unique-Local Addresses (ULAs)
 Similar to Private addresses
▪ They are not expected to be routable on the global
Internet.
 Defined as FC00 or FD00::/7

 Multicast address
 One-to-Many communication packets.
 Multicast packets are identifiable by their first byte.
 Defined as FF00::/8
 In the second byte shown (the “00” of FF00),
 the second 0 is what’s called the scope.
▪ Interface-local is 01, and link-local is 02
▪ FF01:: is an interface-local multicast.
 There are several well-known multicast addresses
 Ex: if you want to send a packet to all nodes in the link-
local scope,
▪ You send the packet to FF02::1 (FF02:0:0:0:0:0:0:1).
▪ The all-routers multicast address is FF02::2

Address Prefix Scope of Use
2000:: /3 Global unicast space prefix
FE80:: /10 Link-local address prefix
FC00:: /7 Unique local unicast prefix
FF00:: /8 Multicast prefix
2001:DB8:: /32 Global unicast prefix use for documentation
::1 - ::/1 Reserved local loopback address
2001:0000: /32 Teredo prefix (discussed later in this chapter)
2002:: /16 6to4 prefix (discussed later in this chapter)

 New Header Format
 Not supported by current IPv4 routers
 Router Upgrade Required Before Moving To
IPv6

 Dual stack
 Running both IPv4 and IPv6 on the same network
 Utilizing the IPv4 address space for devices using only
IPv4 addresses and utilizing the IPv6 address space for
devices using IPv6 addresses
 Tunneling
 Using an encapsulation scheme for transporting one
address space inside another
 Address translation
 Using a higher-level application to transparently change
one address type (IPv4 or IPv6) to the other so end
devices are unaware one address space is talking to
another

 IPv6 Tunneling
 Several tunneling mechanisms for tunneling
IPv6 through the IPv4 address space.
 Used for unicast IPv6 communication across an
IPv4 infrastructure.
 They include the following:
▪ Intra-Site Automatic Tunnel Addressing Protocol
(ISATAP)
▪ 6to4
▪ Teredo

 Intra-Site Automatic Tunnel Addressing Protocol
(ISATAP)
 Allows IPv6 and IPv4 hosts to communicate through a
ISATAP router
▪ By performing a type of address translation between IPv4 and IPv6.
 Intended for use inside a private network.
 Enabled by default in Windows Server 2008.
▪ “Tunnel Adapter Local Area Connection* 8”
 IPv4 embedded in IPv6
▪ e.g., FE80::5EFE:192.168.1.5
 All ISATAP clients receive an address for an ISATAP interface.
 The format of an ISATAP address is as follows:
▪ [64bits of prefix] [32bits indicating ISATAP] [32bits IPv4 Address]

 ISATAP routers allows IPv4-only and IPv6-
only hosts to communicate with each other

 6to4
 Tunnels IPv6 traffic over IPv4 through 6to4 routers.
 Similar to ISATAP, but designed for public network
(Internet)
▪ Intended to be used on the Internets.
 IPv4 is encapsulated in IPv6
 Requires 6to4 routers
▪ Router has public IP
 2002:/16 prefix
▪ Router advertises 2002: subnet ::/64
▪ hosts auto configure 6to4 address

 6to4 allows IPv6-only hosts to
communicate over the Internet

 Toredo
 Similar to 6 to4 but unnecessary to upgrade edge
routers.
 Toredo is used (Preferred) only when no other IPv6
translation is available.
 Allows clients behind an IPv4 NAT to use IPv6 on
the Internet
 Enabled by default in Windows Server 2008.
▪ “Tunnel Adapter Local Area Connection* 9”
 2001::/32 prefix
64 64
32 prefix Teredo IPv4 Internet ID
Hex

 Neighbor Discovery is a set of messages and
processes that determine relationships
between neighboring nodes.
 Some of the ND functions are:
 Router discovery
 Prefix discovery
 Parameter discovery
 Address auto-configuration
 Address resolution
 Duplicate address detection

Lesson 3: IPv6 Fundamentals

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Lesson 3: IPv6 Fundamentals

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