IPV6 Addressing – ahmedhussein

Migrate To IPv6

The development of IPv6 included fixes for IPv4 limitations and other enhancements.
IPv4 is running out of addresses. IPv6 is the successor to IPv4. IPv6 has a much larger 128-bit address space
issues with NAT and the IoT

IPv4 – 4.3 billion addresses
IPv6 – 340 undecillion addresses

These migration techniques can be divided into three categories:

Dual stack -The devices run both IPv4 and IPv6 protocol stacks simultaneously.
Tunneling – A method of transporting an IPv6 packet over an IPv4 network. The IPv6 packet is encapsulated inside an IPv4 packet.
Translation – Network Address Translation 64 (NAT64) allows IPv6-enabled devices to communicate with IPv4-enabled devices using a translation technique similar to NAT for IPv4.

IPv6 Addressing Formats

IPv6 addresses are 128 bits in length and written in hexadecimal.
IPv6 addresses are not case-sensitive and can be written in either lowercase or uppercase.
The preferred format for writing an IPv6 address is x:x:x:x:x:x:x:x, with each “x” consisting of four hexadecimal values.
In IPv6, a hextet is the unofficial term used to refer to a segment of 16 bits, or four hexadecimal values.
Examples of IPv6 addresses in the preferred format:
2001:0db8:0000:1111:0000:0000:0000:0200
2001:0db8:0000:00a3:abcd:0000:0000:1234

Rule 1 – Omit Leading Zero

The first rule to help reduce the notation of IPv6 addresses is to omit any leading 0s (zeros).
Examples:
01ab can be represented as 1ab
09f0 can be represented as 9f0
0a00 can be represented as a00
00ab can be represented as ab
Note: This rule only applies to leading 0s, NOT to trailing 0s, otherwise the address would be ambiguous.

Rule 2 – Double Colon

A double colon (::) can replace any single, contiguous string of one or more 16-bit hextets consisting of all zeros.
Example:
2001:db8:cafe:1:0:0:0:1 (leading 0s omitted) could be represented as 2001:db8:cafe:1::1
Note: The double colon (::) can only be used once within an address, otherwise there would be more than one possible resulting address.

Unicast, Multicast, Anycast

There are three broad categories of IPv6 addresses:
- Unicast – Unicast uniquely identifies an interface on an IPv6-enabled device.
- Multicast – Multicast is used to send a single IPv6 packet to multiple destinations.
- Anycast – This is any IPv6 unicast address that can be assigned to multiple devices. A packet sent to an anycast address is routed to the nearest device having that address.
Note: Unlike IPv4, IPv6 does not have a broadcast address. However, there is an IPv6 all-nodes multicast address that essentially gives the same result.

IPv6 Prefix Length

Prefix length is represented in slash notation and is used to indicate the network portion of an IPv6 address.

The IPv6 prefix length can range from 0 to 128. The recommended IPv6 prefix length for LANs and most other types of networks is /64.

Types of IPv6 Unicast Addresses

Unlike IPv4 devices that have only a single address, IPv6 addresses typically have two unicast addresses:

Global Unicast Address (GUA) – This is similar to a public IPv4 address. These are globally unique, internet-routable addresses.
Link-local Address (LLA) – Required for every IPv6-enabled device and used to communicate with other devices on the same local link. LLAs are not routable and are confined to a single link.

Unique Local Address

The IPv6 unique local addresses (range fc00::/7 to fdff::/7) have some similarity to RFC 1918 private addresses for IPv4, but there are significant differences:

Unique local addresses are used for local addressing within a site or between a limited number of sites.
Unique local addresses can be used for devices that will never need to access another network.
Unique local addresses are not globally routed or translated to a global IPv6 address.

IPv6 GUA

IPv6 global unicast addresses (GUAs) are globally unique and routable on the IPv6 internet.

Currently, only GUAs with the first three bits of 001 or 2000::/3 are being assigned.
Currently available GUAs begins with a decimal 2 or a 3 (This is only 1/8th of the total available IPv6 address space).

IPv6 GUA Structure

Global Routing Prefix:

The global routing prefix is the prefix, or network, portion of the address that is assigned by the provider, such as an ISP, to a customer or site. The global routing prefix will vary depending on ISP policies.

Subnet ID:

The Subnet ID field is the area between the Global Routing Prefix and the Interface ID. The Subnet ID is used by an organization to identify subnets within its site.

Interface ID:

The IPv6 interface ID is equivalent to the host portion of an IPv4 address. It is strongly recommended that in most cases /64 subnets should be used, which creates a 64-bit interface ID

IPv6 LLA

An IPv6 link-local address (LLA) enables a device to communicate with other IPv6-enabled devices on the same link and only on that link (subnet).

Packets with a source or destination LLA cannot be routed.
Every IPv6-enabled network interface must have an LLA.
If an LLA is not configured manually on an interface, the device will automatically create one.
IPv6 LLAs are in the fe80::/10 range.

Dynamic Addressing for IPv6 GUAs

Method 1: SLAAC

SLAAC allows a device to configure a GUA without the services of DHCPv6.
Devices obtain the necessary information to configure a GUA from the ICMPv6 RA messages of the local router.
The prefix is provided by the RA and the device uses either the EUI-64 or random generation method to create an interface ID.

Dynamic Addressing for IPv6 GUAs

Method 2: SLAAC and Stateless DHCP

An RA can instruct a device to use both SLAAC and stateless DHCPv6.
The RA message suggests devices use the following:
- SLAAC to create its own IPv6 GUA
- The router LLA, which is the RA source IPv6 address, as the default gateway address
- A stateless DHCPv6 server to obtain other information such as a DNS server address and a domain name

Dynamic Addressing for IPv6 GUAs

Method 3: Stateful DHCPv6

An RA can instruct a device to use stateful DHCPv6 only.
Stateful DHCPv6 is similar to DHCP for IPv4. A device can automatically receive a GUA, prefix length, and the addresses of DNS servers from a stateful DHCPv6 server.
The RA message suggests devices use the following:
- The router LLA, which is the RA source IPv6 address, for the default gateway address.
- A stateful DHCPv6 server to obtain a GUA, DNS server address, domain name and other necessary information.

EUI-64 Process

When the RA message is either SLAAC or SLAAC with stateless DHCPv6, the client must generate its own interface ID.
The interface ID can be created using the EUI-64 process or a randomly generated 64-bit number.
A 16 bit value of fffe (in hexadecimal) is inserted into the middle of the 48-bit Ethernet MAC address of the client.
The 7th bit of the client MAC address is reversed from binary 0 to 1.

IPv6 Neighbor Discovery Messages

IPv6 Neighbor Discovery (ND) protocol provides:

Address resolution
Router discovery
Redirection services
ICMPv6 Neighbor Solicitation (NS) and Neighbor Advertisement (NA) messages are used for device-to-device messaging such as address resolution.
ICMTPv6 Router Solicitation (RS) and Router Advertisement (RA) messages are used for messaging between devices and routers for router discovery.

ICMPv6 redirect messages are used by routers for better next-hop selection

IPv6 Neighbor Discovery – Address Resolution

IPv6 devices use ND to resolve the MAC address of a known IPv6 address.
ICMPv6 Neighbor Solicitation messages are sent using special Ethernet and IPv6 multicast addresses.

IPv6 Subnetting

LAB Configuration

interface g0/1
ipv6 address 2001:db8:6783:20::1/64

do show ipv6 int g0/1
do show run

client enable auto config
ipv6config /all
it does not have dns server

ipv6 dhcp pool ourpool
dns-server 2001:db8:6783:30::3

interface g0/1
ipv6 dhcp server ourpool
ipv6 nd other-config-flag
end
show run
client
ipv6config /all and check dns

Physical LAB Stateful DHCPv6

ipv6 unicast-routing
ipv6 dhcp pool IPV6POOL-A
address prefix 2001:DB8:ACAD:A::/64
dns-server 2001:DB8:ACAD:A::ABCD
domain-name ccna-StatefulDHCPv6.com

!
interface GigabitEthernet0/0
no shutdown
ipv6 address 2001:DB8:ACAD:A::1/64
ipv6 nd managed-config-flag
ipv6 dhcp server IPV6POOL-A

59

Created on December 10, 2022

IPv6 Quiz

Test Your Understanding

1 / 14

At a minimum, which address is required on IPv6-enabled interfaces?

site local

global unicast

link-local

unique local

All IPv6 enabled interfaces must at minimum have a link-local address. Other IPv6 addresses can be assigned to the interface as required.

2 / 14

What is the minimum configuration for a router interface that is participating in IPv6 routing?

to have a self-generated loopback address

to have only an automatically generated multicast IPv6 address

to have only a link-local IPv6 address

to have both an IPv4 and an IPv6 address

to have both a link-local and a global unicast IPv6 address

With IPv6, a router interface typically has more than one IPv6 address. The router will at least have a link-local address that can be automatically generated, but the router commonly has an global unicast address also configured.

3 / 14

What type of address is automatically assigned to an interface when IPv6 is enabled on that interface?

link-local

global unicast

loopback

unique local

When IPv6 is enabled on any interface, that interface will automatically generate an IPv6 link-local address.

4 / 14

What is indicated by a successful ping to the ::1 IPv6 address?

The link-local address is correctly configured.

All hosts on the local link are available.

The host is cabled properly.

IP is properly installed on the host.

The default gateway address is correctly configured.

The IPv6 address ::1 is the loopback address. A successful ping to this address means that the TCP/IP stack is correctly installed. It does not mean that any addresses are correctly configured.

5 / 14

What is the most compressed representation of the IPv6 address 2001:0000:0000:abcd:0000:0000:0000:0001?

2001::abcd::1

2001:0:abcd::1

2001:0:0:abcd::1

2001::abcd:0:1

2001:0000:abcd::1

The IPv6 address 2001:0000:0000:abcd:0000:0000:0000:0001 in its most compressed format would be 2001:0:0:abcd::1. The first two hextets of zeros would each compress to a single zero. The three consecutive hextets of zeros can be compressed to a double colon ::. The three leading zeros in the last hextet can be removed. The double colon :: can only be used once in an address.

6 / 14

What is the valid most compressed format possible of the IPv6 address 2001:0DB8:0000:AB00:0000:0000:0000:1234?

2001:DB8:0:AB00::1234

2001:DB8::AB00::1234

2001:DB8:0:AB:0:1234

2001:DB8:0:AB::1234

There are two rules defining how an IPv6 address can be compressed. The first rule states that leading zeros in a hextet can be eliminated. The second rule states that a single :: can be used to represent one or more contiguous all zero hextets. There can be one and only one :: in an IPv6 address.

7 / 14

Which type of IPv6 address is not routable and used only for communication on a single subnet?

global unicast address

unique local address

loopback address

unspecified address

link-local address

Link-local addresses have relevance only on the local link. Routers will not forward packets that include a link-local address as either the source or destination address.

8 / 14

What is the interface ID of the IPv6 address 2001:DB8::1000:A9CD:47FF:FE57:FE94/64?

47FF:FE57:FE94

FE57:FE94

A9CD:47FF:FE57:FE94

1000:A9CD:47FF:FE57:FE94

FE94

The interface ID of an IPv6 address is the rightmost 64 bits, or last four hextets, of the address if no interface ID bits have been used for subnets.

9 / 14

Your organization is issued the IPv6 prefix of 2001:0000:130F::/48 by your service provider. With this prefix, how many bits are available for your organization to create subnetworks if interface ID bits are not borrowed?

16

128

8

80

The global routing prefix that is assigned to the organization has 48 bits. The next 16 bits are used for the subnet ID. This makes up the first 64 bits of the address, which is typically the network portion of the address. The remaining 64 bits of the 128-bit IPv6 address are for the interface ID (or host) portion of the address.

10 / 14

What are three parts of an IPv6 global unicast address? (Choose three.)

a global routing prefix that is used to identify the portion of the network address provided by a local administrator

a global routing prefix that is used to identify the network portion of the address that has been provided by an ISP

a subnet ID that is used to identify networks inside of the local enterprise site

an interface ID that is used to identify the local host on the network

an interface ID that is used to identify the local network for a particular host

There are three elements that make up an IPv6 global unicast address. A global routing prefix which is provided by an ISP, a subnet ID which is determined by the organization, and an interface ID which uniquely identifies the interface interface of a host.

11 / 14

Which IPv6 network prefix is only intended for local links and can not be routed?

FC00::/7

2001::/3

FEC0::/10

FE80::/10

FE80::/10 is a link-local prefix. Devices with only link-local addresses can communicate with other devices on the same network but not with devices on any other network.

12 / 14

What is the subnet address for the IPv6 address 2001:D12:AA04:B5::1/64?

2001:D12:AA04::/64

2001:D12::/64

2001:D12:AA04:B5::/64

2001::/64

The /64 represents the network and subnet IPv6 fields which are the first four groups of hexadecimal digits. The first address within that range is the subnetwork address of 2001: D12:AA04:B5::/64.

13 / 14

Which address type is not supported in IPv6?

broadcast

private

multicast

unicast

IPv6 supports unicast, private, and multicast addresses but does not support Layer 3 broadcasts.

14 / 14

What is the prefix associated with the IPv6 address 2001:CA48:D15:EA:CC44::1/64?

2001::/64

2001:CA48:D15:EA:CC44::/64

2001:CA48:D15:EA::/64

2001:CA48::/64

The /64 represents the network and subnet IPv6 fields. The fourth field of hexadecimal digits is referred to as the subnet ID. The subnet ID for this address is 2001:CA48:D15:EA::0/64.

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