ISO 9001:2008

Pankaj Kumar

Dir, TEC, DOT

AWARENESS OBJECTIVES

• IPv6 Address Format & Basic Rules

• Understanding the IPv6 Address

Components

• Understanding & Identifying Various

Types of IPv6 Addresses

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W . X . Y . Z

192 . 168 . 5 . 1

W,X,Y,Z represent 8 bits converted to Decimal

XXXX : XXXX : XXXX : XXXX : XXXX : XXXX : XXXX : XXXX

Where each x represent a 4 bits hexadecimal field

2001:0DB8:1234:0000:0000:C1C0:ABCD:0876

IPv6 Address SYNTAX

IPv4 Address SYNTAX

• The following is an IPv6 address in binary form:

0010000000000001000011011011100000000000000000000010111100111011

0000001010101010000000001111111111111110001010001001110001011010

• The 128-bit address is divided along 16-bit blocks:

0010000000000001 0000110110111000 0000000000000000 0010111100111011

0000001010101010 0000000011111111 1111111000101000 1001110001011010

• Each 16-bit block is converted to hexadecimal – taking 4 bits as one block- and

delimited with colons. The result is :

Second 16 bits block is 0000 1101 1011 1000

0 D B 8

Thus, the 8 blocks are represented as :

2001:0DB8:0000:2F3B:02AA:00FF:FE28:9C5A

FROM 128 BIT BINARY TO 8 BLOCK OF „HEXTETS‟

IPv6 Address Capacity

IPv4: 32 bits or 4 bytes long

4.2 billion possible IP addresses

• IPv6: 128 bits or 16 bytes

• 340* 1036 possible IP addresses

• 340 undecillion or 340 trillion trillion trillion

• 340 lakh lakh lakh crores !!

IPv6

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2001:0DB8:0000:003B:02AA:00FF:FE28:0C5A

It is Case Insensitive colon hextet notation

2001:0Db8:0000:003B:02aa:00ff:FE28:0C5A

RULE 1

Rule 2

2001:0Db8:0000:003B:02aa:00ff:FE28:0C5A

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The leading zeros within each 16-bit block can be

removed. However, each block must have at least a

single digit

2001:0Db8:0000:003B:02aa:00ff:FE28:0C5A

2001:Db8:0:3B:2aa:ff:FE28:C5A

A contiguous sequence of 16-bit blocks set to 0 in the colon

hexadecimal format can be compressed to “::”, double-colon

Zero compression can only be used once in a given address

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• FF02:0:0:0:0:0:0:1 FF02::1

• FE80:0:0:0:2AA:FF:FE9A:4CA2 FE80::2AA:FF:FE9A:4CA2

2001:0:0:1234:0:0:0:C1C0

2001::1234::C1C0

SUPPRESSION OF CONTIGUOUS SEQUENCE OF „0‟

RULE 3

In a URL, it is enclosed in brackets

http://[2001:1:4F3A::206:AE14]

If writing Domain name in the URL, Should use Fully

Qualified Domain Names (FQDN)

IPv6 Addresses in URL

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2001:0A3C:5437:ABCD:0:0:0:0/64

PrefixInterface ID

IPv6 Prefixes

• Certain fixed numbers of high-order bits of an IPv6

address may specify an ISP Network, a site within an

organisation or a subnet

• Prefixes for IPv6 Addresses are expressed in the same

way as CIDR notation in IPv4.

• An IPv6 prefix is written in /N-length notation; N -Decimal

• For example, 21DA:D3::/48 and 21DA:D3:0:2F3B::/64 ;

/48 AND /64 are IPv6 address prefixes.

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IPv6 Interface Identifiers

• Fixed Sixty-four LSB bits of IPv6 address. Guaranteed

unique on the subnet

• In IPv4, hosts ID are of variable length depending upon the

sub netting scheme whereas in IPv6 Interface ID is of fixed

length as 64 bits

• Mapping IEEE 802 48 bit MAC address into 64 bit Interface

ID (EUI-64)

• In IPV6 nodes can generate its Interface ID automatically

Mapping IEEE 802 MAC address into

interface identifier

48 bit MAC ID

Insert FF FE

Invert the 7th bit

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UNICAST

ANYCAST

MULTICAST

IPv6 Address scope

Link-local: The scope is the local link (nodes on the same subnet)

Site-local: The scope is the site of an organization (private site addressing) – Now Deprecated

Unique – Local : Scope is the organization ; Similar to Private IPv4 addresses

Global: The scope is global (IPv6 public addresses)

IPv6

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Unicast IPv6 Addresses

• Global

• Link-local

• Unique-Local

Global Unicast AddressesGlobal unicast addresses are equivalent to public IPv4 addresses. They

are globally routable and reachable on the IPv6 portion of the Internet

Format Prefix 2000::/3

First 3 bits (001) are fixed; next 45 bit prefix- collection of larger and smaller ISPs that

provide access to the IPv6 Internet

Next 16 bits- Collection of subnets within an organization’s site

The interface ID 64 bit- identifies a specific interface on a subnet within an

organization’s site

001 – First 3 bits are Reserved

• IANA has only released 1/8th of the entire IPv6 addresses

• For this, first 3 MSB are fixed as 001

• The entire global-unicast IPv6 address range is from

2000::/128 to 3FFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF/128,

which is only 1/8th of the entire IPv6 address space!

Global Unicast Address Allocation

• IETF RFC 3177 recommended /48 block to end sites

• However, RIRs adopted /56 or /64 blocks

• Now IETF released RFC 6177, which allows flexibility to

the RIRs in allocation of address block to end sites

• But it recommends blocks larger than /64 so that end

sites may grow into multiple subnet.

• Top level ISP gets /30 or /32

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LLA SLA ULA

IPv6 Link Local Unicast Address (LLA)IPv6

Hosts on the same link (the same subnet) use

these automatically configured addresses to

communicate with each other.

Must for the Neighbor Discovery protocol

The prefix Format for LLA is FE80::/64.

The prefix Format for LLA

IPv6 Unique Local Address (ULA) IPv6

Replaces Site Local Addresses

Equivalent to Private IP addresses in IPv4

Provides unique Private IPv6 addresses across all sites of an

organization

Removes The ambiguity of non- unique site-local addresses

in an organization

The Format prefix for ULA is FC00::/7.

The Prefix

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Loopback Unspecified

Transition

Special Unicast Addresses

• Unspecified address

– 0:0:0:0:0:0:0:0 or :: (0.0.0.0 in IPv4)

– is only used to indicate the absence of an address

– The unspecified address is typically used by the node

to know its address when plugged into the network.

• Loopback address– 0:0:0:0:0:0:0:0:1 or ::1 ( 127.0.0.1 in IPv4)

– used to identify a loopback interface, enabling a node to send

packets to itself

Compatibility Addresses

• IPv4-compatible address– 0:0:0:0:0:0:w.x.y.z or ::w.x.y.z

– where w.x.y.z is the dotted decimal representation of an IPv4

address

– used by hosts that are communicating with IPv6 over an IPv4

network

• IPv4-mapped address– 0:0:0:0:0:ffff:w.x.y.z or ::ffff:w.x.y.z

– used to map IPv4 devices that are not compatible with IPv6 into

the IPv6 address space

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MULTICAST ADDRESS

• One to many communication

• IPv6 nodes can listen to multiple multicast addresses at

the same time

• No Broadcast Address in IPv6

IPv6 Multicast address Format Prefix FF00::/8

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Anycast IPv6 Addresses

• One-to-nearest

• Anycast addresses allow packet to be routed to one of a

number of different nodes all responding to the same

address

• are allocated from the unicast address space

• It cannot be distinguished from a Unicast address

• Used only as Destination Address and may be

assigned to an IPv6 router only

Anycast IPv6 Address Uses

• Multiple Router on a remote subnet

• Multi Homing

• Multiple DNS server on a subnet

• Content delivery Networks

• IPv4 to IPv6 transition • 6 to4 networks

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Address Auto Configuration

• Unique feature of IPv6 enabling automatic configuration

of various types of IPv6 address by the IPv6 host

• By default IPv6 host can configure Link local address• FE80::EUI-64 Interface ID

• Site local and Global IPv6 address can also be

configured automatically without the help of DHCP server

Why does this matter?

• Manual configuration of individual machines before connecting them to the network may not be required.– Only the Router & Server require Manual configuration

• Provide Plug-and-play communication

• A large site with multiple networks and routers should not require the presence of a statefull address configuration server.

• Enables small sensors to work in IPv6 network

• It may be one of the killer feature of IPv6

Hence, to Summarise

• IPv6 address is 128 bit long written in eight block of

hexadecimal field

• Almost Infinite numbers of IPv6 addresses

• IPv6 address HAS TWO PART – Routing prefix and

Interface Identifier

• Unicast, Multicast, Anycast IPv6 Addresses with specific

format prefix

• Nodes can auto configure IPv6 addresses

gkf nZd/ kU; okn

RECALL BY TRYING THIS

• Match the following

A. Link local address prefix i. FF00::/8

B. Unique local address prefix ii. FE80::/64

C. Multicast address Prefix iii. 2001::/3

D. Global address prefix iv. FD00::/8

IPv6 Address Planning: BSNL

• BSNL got 2001:4490::/30 from APNIC for IPv6

Implementation

• /30 is divided into four /32 blocks

• Only one /32 block planned for use now

• /32 block is divided into sixteen /36 blocks; each block for

different services

• Example : Mobile : /38 to each zone ; /39 post paid /39

pre-paid

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IPv6 Interface Identifiers

• Fixed Sixty-four LSB bits of IPv6 address. Guaranteed

unique on the subnet

• In IPv4, hosts ID are of variable length depending upon

the sub netting scheme whereas in IPv6 Interface ID is of

fixed length as 64 bits

• Essentially same as EUI-64

• Mapping IEEE 802 MAC address into interface identifier

• Randomly generated interface identifier to provide a level

of anonymity

INTERFACE ID : ILLUSTRATION

Mapping IEEE 802 MAC address into

interface identifier

• EUI-64 from MAC addresses:

– MAC Address : 00-02-2D-02-82-34

– IPv6 Interface ID : 0202:2dff:fe02:8234

• The Rules :

– Insert FFFE after the first 3 octets

– Last 3 octets remain the same

– Invert the 7TH bit from the left of the first octet.

• Universal/local bit

EUI-64 Mapping Illustration

Types of Address

Autoconfiguration• Stateless

– Configuration of addresses is based on the receipt of

Router Advertisement messages which provides

prefix – Prefix + Interface Id = IPv6 address

• Stateful

– Configuration is based on the use of a stateful

address configuration protocol such as DHCPv6 to

obtain addresses and other configuration options

• Both

– IP address is stateless configured but other

configurations are stateful

Process of Stateless Autoconfiguration

Auto configure link local address

Verifies its uniqueness – Neighbour

solicitation & Neighbour Advertisement

Obtain prefix and other information from

Router – Router solicitation and Router

Advertisement

Configure Global IPv6 address by

combining Link Prefix with Interface ID

Verify its uniqueness – Duplicate Address

Detection

STATELESS AUTO CONFIGURATION : ILLUSTRATION

Global Address=Link Prefix + EUI 64 Address

Router Address is the Default Gateway

Stateless Autoconfiguration Example

IPv6

MAC address : 00:2C:04:00:FF:56

EUI 64 Address: 022C:04FF:FE00:FF56

Auto configured Link Local Address : FE80::22C:04FF:FE00:FF56

Link Prefix2001:690:1:1

Configured Global IPv6 Address

2001:690:1:1:22C:04FF:FE00:FF56

Finally Try This One

• MAC Address : 00:08:C7:1B:8C:02

• Router IP address :

2001:3452:4952:2837::

• Find the auto configured IPv6 address by

the host on this link

IPv6 Address Types

IPv6

UnicastAddress is for a single interface.

IPv6 has several types (for example, global and IPv4 mapped).

MulticastOne-to-many

Enables more efficient use of the network

Uses a larger address range

AnycastOne-to-nearest (allocated from unicast address space).

Multiple devices share the same address.

All anycast nodes should provide uniform service.

Source devices send packets to anycast address.

Routers decide on closest device to reach that destination.

Suitable for load balancing and content delivery services.

STRUCTURE OF IPv6 MULTICAST ADDRESS

Scope – Indicates the scope of the IPv6 internetwork for which the

multicast traffic is intended

The most prevalent values for the Scope field are 1 (interface-local scope), 2

(link-local scope), 5 (site-local scope), 8 (Organisation – local), and E (Global)

IPv6 Multicast address Format Prefix FF00::/8

Flag :Only the LSB flag is defined : 0 – Permanently Assigned; 1- transient

1 all-nodes

2 all-routers

Neighbor Discovery

IPv6

IPv6 nodes which share the same physical

medium (link) use Neighbor Discovery (NDP) to:

Discover their mutual presence

Determine link-layer addresses of their neighbors

(equivalent to ARP)

Find routers

Maintain neighbors’ reachability information

Uses Multicast Address

Neighbor Discovery

IPv6

Protocol features:Router discovery

Prefix(es) discovery

Parameters discovery (link MTU, Max Hop Limit, ...)

Address auto-configuration

Address resolution

Next Hop determination

Neighbor Unreachability Detection

Duplicate Address Detection

Redirect

Neighbor Discovery

IPv6

It provides the functionality of:

ARP

ICMP redirect

Neighbor Discovery

IPv6

ND specifies 5 types of ICMP packets:

Router Advertisement (RA) :

Periodic advertisement (of the availability of a router)

which contains:

»list of prefixes used on the link (autoconf)

»a possible value for Max Hop Limit (TTL of IPv4)

»value of MTU

Router Solicitation (RS) :

The host needs RA immediately (at boot time)

Neighbor Discovery

IPv6

Neighbor Solicitation (NS):

»to determine the link-layer address of a neighbor

»or to check its reachability

»also used to detect duplicate addresses (DAD)

Neighbor Advertisement (NA):

»answer to a NS packet

»to advertise the change of physical address

Redirect:

»Used by a router to inform a host of a better route to a given destination

6/4 Dual Stack Hosts and Network

IPv6

This allows all the end hosts and intermediate

network devices (like routers, switches, modems

etc.) to have both IPv4 and IPv6 addresses and

protocol stack.

If both the end stations support IPv6, they can

communicate using IPv6; otherwise they will

communicate using IPv4.

This will allow both IPv4 and IPv6 to coexist and

slow transition from IPv4 to IPv6 can happen.

6/4 Dual Stack Hosts and Network

IPv6

6/4 Dual Stack Hosts and Network

IPv6

IITK_KNPR_CMTR_DIA#sh run

Building configuration...

interface GigabitEthernet0/1

description Connected to IITK

ip address 203.197.196.18 255.

ipv6 address 2001:DF0:92::1/64

ipv6 enable

!

interface GigabitEthernet0/2

description Airtel IPv6 Connectivity

ip address 59.144.72.85 255.255.255.2

ipv6 address 2404:A800:2:D::2/64

ipv6 enable

!

Tunneling IP6 via IP4

IPv6

This allows encapsulating IPv6 packets in IPv4

Datagram for transport over IPv4 only network.

This will allow IPv6 only end stations to

communicate over IPv4 only networks.

IPV6 Address SYNTAX

XXXX : XXXX : XXXX : XXXX : XXXX : XXXX : XXXX : XXXX

Where each x represent a 4 bits hexadecimal field

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2001:0000:1234:0000:0000:C1C0:ABCD:0876

X:x :x :x :x :x :x :x

Each X Represent 16 Bits converted in Hexadecimal

IP6-IP4 Translation

IPv6

This allows communication between IPv4 only

and IPv6 only end stations.

The job of the translator is to translate IPv6 packetsinto IPv4 packets by doing address and porttranslation and vice versa.

IPv6 Site Local Unicast Address

IPv6

IPv6 unicast site-local addresses are similar to

IPv4 private addresses.

The scope of a site-local address is the

inter-network of an organization’s site.

The prefix for site-local addresses is FEC0::/48.

RFC 3879 formally deprecates the use of site-local addresses

for future IPv6 implementations

Structure of a site-local address.