IP Version 6

Question 1

Prefix ID

Answer 1

The first 64 bits of the IPv6 address. The prefix can be divided into various parts that identify things such as geographic region, ISP, network, and subnet.

Question 2

Interface ID

Answer 2

The last 64 bits of the IPv6 address. This is a unique identifier for each device, similar to a MAC address.

Question 3

Tunneling

Answer 3

Allows IPv6 hosts or sites to communicate over the existing IPv4 infrastructure.

Question 4

Unicast address

Answer 4

An address assigned to a single interface for the purpose of allowing one host to send and receive data. Packets sent to a unicast address are delivered to the interface identified by that address.

Question 5

Multicast address

Answer 5

An address that represents a dynamic group of hosts.

Question 6

Anycast address

Answer 6

A unicast address assigned to more than one interface, typically belonging to different hosts.

Question 7

Loopback address

Answer 7

A special IP address that can be used to verify that the TCP/IP protocol stack is properly installed on the host. The local loopback address is not assigned to an interface.

Question 8

Prefix

Answer 8

The first 64-bits make up the prefix.
The prefix can be divided into various parts that identify things such as geographic region, the ISP, the network, and the subnet.
The first 48-bits of the address define the site prefix. The site prefix defines the location of the address and is assigned by the local ISP.
The next 16-bits make up the subnet ID. This defines the network that the device is connected to.
CIDR notation is used to indicate the prefix-length. Just like in an IPv4 address, this indicates the portion of the address that is being used for the prefix (network address).
To indicate the prefix length, add a slash (/) followed by the prefix length number. Full quartets with trailing 0s in the prefix address can be omitted (e.g., 2001:0DB8:4898:DAFC::/64).
Because addresses can be allocated based on physical location, the prefix generally identifies the location of the host. The prefix is often referred to as the global routing prefix.

Question 9

Interface ID

Answer 9

The last 64-bits in the address is the interface ID. This is a unique identifier for each device, similar to a MAC address.
Addresses are assigned to interfaces (network connections), not to the host. Technically, the interface ID is not a host address, but is often referred to as the host address.
Interface IDs must be unique within a subnet, but they can be the same if they are on different subnets.
To ensure that the interface ID is unique for every host on the network, IPv6 uses the Extended Unique Identifier 64 (EUI-64) format. EUI-64 format details include:

Since each device is hard-wired with a unique 48-bit hardware address called the MAC address, IPv6 can use it to generate a unique interface ID. The EUI-64 format uses the unique MAC address as follows:
The MAC address is converted into binary.
The 7 th bit from the left is flipped (from 1 to 0 or 0 to 1). This bit is called the universal/local (U/L) bit.
The 16-bit hexadecimal value FFFE is inserted in the middle.
This gives a 64-bit interface ID.

For example, a host with a MAC address of 20-0C-FB-BC-A0-07 would start with the following EUI-64 interface ID:
220C:FBFF:FEBC:A007
(Notice the FF:FE in the center of the address.)
The interface ID can also be generated using a special algorithm that generates a completely randomized ID. This guarantees that each device will have a unique ID.

Question 10

Auto-configuration

Answer 10

Because hardware IDs are used for node IDs, IPv6 nodes need only to discover their network IDs. This can be done by communicating with a router.

Question 11

Built-in quality of service

Answer 11

Built-in support for bandwidth reservations makes guaranteed data transfer rates possible. Quality of service features are available as add-ons within an IPv4 environment but are not part of the native protocol.

Question 12

Built-in security features

Answer 12

IPv6 has built-in support for security protocols such as IPsec. IPsec security features are available as add-ons within an IPv4 environment.

Question 13

Source intelligent routing

Answer 13

IPv6 nodes have the option to include addresses that determine part or all of the route a packet will take through the network.

Question 14

dual stack configuration

Answer 14

enables a host to communicate with both IPv4 and IPv6 hosts. In a dual stack configuration, the network adapter for each device on the network must support both IPv4 and IPv6. These devices can transmit and receive packets of both IP versions in parallel. When dual stack is implemented on hosts, intermediate routers and switches must also run both protocol stacks.

Question 15

IP Tunneling

Answer 15

Another strategy is to implement an appropriate tunneling method. Tunneling allows IPv6 hosts or sites to communicate over the existing IPv4 infrastructure. A device encapsulates IPv6 packets in IPv4 packets for transmission across an IPv4 network. The IPv6 packets are de-encapsulated by another device at the other end.

Question 16

Manually configured tunnel

Answer 16

In this configuration, tunnel endpoints are configured as point-to-point connections between devices. Because of the time and effort required for configuration, use manually configured tunnels only when:
You have a small number of sites that need to connect through the IPv4 internet.
You want to configure secure site-to-site associations.
Manual tunneling:

Is configured between routers at different sites.
Requires dual stack routers as the tunnel endpoints, but is compatible with IPv6-only hosts.
Can be used to send data over the internet.
Uses a static association of an IPv6 address to the IPv4 address of the destination tunnel endpoint.

Question 17

6-to-4 tunneling

Answer 17

With 6-to-4 tunneling, tunneling endpoints are configured automatically between devices. Use 6-to-4 tunneling to dynamically connect multiple sites through the IPv4 internet. Because of its dynamic configuration, 6-to-4 tunneling is easier to administer than manual tunneling.
6-to-4 tunneling:

Is configured between routers at different sites.
Requires dual stack routers as the tunnel endpoints, but can work with IPv6-only hosts.
Can be used to send data over the internet.
Uses a dynamic association of an IPv6 site prefix to the IPv4 address of the destination tunnel endpoint.
Automatically generates an IPv6 address for the site using the 2002::/16 prefix followed by the public IPv4 address of the tunnel endpoint router.
For example, a router with an IPv4 address of 207.142.131.202 would serve the site with the following prefix:
2002:CF8E:83CA::/48
CF8E:83CA is the hexadecimal equivalent of 207.142.131.202.

Question 18

4-to-6 tunneling

Answer 18

4-to-6 tunneling works in a manner similar to 6-to-4 tunneling. However, instead of tunneling IPv6 traffic through an IPv4 network, 4-to-6 tunnels IPv4 traffic through an IPv6 network by encapsulating IPv4 packets within IPv6 packets.

Question 19

Intra-site Automatic Tunnel Addressing Protocol
(ISATAP)

Answer 19

The Intra-site Automatic Tunnel Addressing Protocol is a tunneling method that provides IPv6 communication over a private IPv4 network.
ISATAP tunneling:

Is configured between individual hosts and an ISATAP router.
Requires a special dual stack ISATAP router to perform tunneling and dual stack or IPv6-only clients. Dual stack routers and hosts perform tunneling when communicating on the IPv4 network.
Can be used only for intra-site communication. It cannot transmit packets across the internet.
Automatically generates link-local addresses that include the IPv4 address of each host, as follows:
The prefix is the well-known link-local prefix: FE80::/16.
The remaining prefix values are set to 0.
The first two quartets of the interface ID are set to 0000:5EFE.
The remaining two quartets use the IPv4 address written in either dotted decimal or hexadecimal notation.
For example, a host with the IPv4 address 192.168.12.155 would have the following IPv6 address when using ISATAP:
FE80::5EFE:C0A8:0C9B
It can also be designated as FE80::5EFE:192.168.12.155.

Question 20

Unicast addresses

Answer 20

are assigned to a single interface for the purpose of allowing one host to send and receive data. Packets sent to a unicast address are delivered to the interface identified by that address.
There are three types of unicast IPv6 addresses: link-local, unique, and global.

Question 21

Link-local

Answer 21

Link-local addresses (also known as local link addresses) are valid only on the current subnet. These addresses are similar to an APIPA IPv4 address. Details include the following:
Link-local addresses have an FE80::/10 prefix. This includes any address beginning with FE8, FE9, FEA, or FEB.
All nodes must have at least one link-local address, although each interface can have multiple addresses.
Link-local addresses are used for automatic address configuration, for neighbor discovery, or for subnets that have no routers.
Do not use link-local IPv6 addressing on routed networks. Routers never forward packets destined for link-local addresses to other subnets.

Question 22

Unique local

Answer 22

Unique local addresses are private addresses used for communication within a site or between a limited number of sites. In other words, unique local addressing is commonly used for network communications that do not cross a public network; they are the equivalent of private addressing in IPv4.

Details include the following:
Because unique local addresses are not registered with IANA, they cannot be used on a public network without address translation.
Unique local addresses have an FC00::/7 prefix and include addresses beginning with FC or FD
Following the prefix, the next 40 bits are used for the Global ID. The Global ID is generated randomly, creating a high probability of uniqueness on the entire internet.
Following the Global ID, the remaining 16 bits in the prefix are used for subnet information.
Unique local addresses are likely to be globally unique, but they are not globally routable. Unique local addresses might be routed between sites by a local ISP.
The process for designing a network addressing scheme when using unique local addresses is similar to that used for global unicast addresses. The key difference is how the prefix is defined. Because the address range is not registered:
A global routing prefix does not have to be requested from an ISP.
Each organization defines its own prefix.

Question 23

Global unicast

Answer 23

Global unicast addresses are assigned to individual interfaces that are globally unique. Key facts about global unicast address include:
All IPv6 addresses that aren’t specifically reserved for other purposes are defined as global unicast addresses.
The global routing prefix assigned to an organization by an ISP is typically 48 bits long (/48), but it could be as short as /32 or as long as /56, depending on the ISP.
All subnet IDs within the same organization must begin with the same global routing prefix, but they must also be uniquely identified using a different value in the subnet field.
Using this addressing scheme allows organizations to define a large number (2 16 ) of IPv6 subnets.
When designing an IPv6 network, separate IPv6 subnets can be defined by the following:
Network segments separated by routers
VLANs
Point-to-point WAN links

Question 24

Multicast

Answer 24

Multicast addresses represent a dynamic group of hosts. Packets sent to a multicast address are sent to all interfaces identified by that address. If different multicast addresses are used for different functions, only the devices that need to participate in a particular function will respond to the multicast; devices that do not need to participate in the function will ignore the multicast.

Details include the following:
All multicast addresses have an FF00::/8 prefix.
Multicast addresses that are restricted to the local link have only an FF02::/16 prefix. Packets starting with FF02 are not forwarded by routers.
Multicast addresses with an FF01::/16 prefix are restricted to a single node.
The following are well-known multicast addresses:
FF02::1 is for all nodes on the local link. This is the equivalent of the IPv4 subnet broadcast address. FF01::1 is for all interfaces on a node.
FF02::2 is for all routers on the local link. FF01::2 is for all routers on node-local.
FF02::1:2 is for all DHCP servers or DHCP relay agents on the local link. DHCP relay agents forward these packets to other subnets.
There are no broadcast addresses in IPv6. IPv6 multicast addresses are used instead of broadcast addresses.

Question 25

Anycast

Answer 25

The anycast address is a unicast address that is assigned to more than one interface, typically belonging to different hosts. An anycast packet is routed to the nearest interface having that address (based on routing protocol decisions).

Details include the following:
An anycast address is the same as a unicast address. Assigning the same unicast address to more than one interface makes it an anycast address.
An anycast address can be a link-local, unique local, or global unicast address.
When assigning an anycast address to an interface, it must be explicitly identified as an anycast address to distinguish it from a unicast address.
Anycast addresses can be used to locate the nearest server of a specific type (for example, the nearest DNS or network time server).

Question 26

Loopback

Answer 26

The local loopback address for the local host is 0:0:0:0:0:0:0:1 (also identified as ::1 or ::1/128). The local loopback address is not assigned to an interface. It can verify that the TCP/IP protocol stack is properly installed on the host.

Question 27

Static full assignment

Answer 27

The entire 128-bit address and all other configuration information is statically assigned to the host. The network administrator is responsible for manually configuring each individual device and updating any changes.

Question 28

Static partial assignment

Answer 28

The prefix is statically assigned, but the interface ID uses the modified EUI-64 format that is derived from the MAC address.

Question 29

Stateless address autoconfiguration
(SLAAC)

Answer 29

Clients automatically generate the interface ID and learn the subnet prefix and default gateway through the Neighbor Discovery Protocol (NDP).

The process is as follows:
The device generates a link-local IPv6 address using the FE80::/10 prefix and modifies its MAC address to get the interface ID using the EUI-64 format.
The device verifies that the address is not already in use by using duplicate address detection (DAD).
A neighbor solicitation message is sent to a multicast address.
If another device has the same address, it responds with a neighbor advertisement message and the process stops. The device will need to be manually configured.
If no other devices respond with the same address, the process continues.
If no conflicting addresses are found, the device sends a router solicitation (RS) message addressed to all routers on the subnet using the multicast address FF02::2.
The nearest router responds back with the global unicast address prefix. The host combines this with it’s interface ID to generate it’s IPv6 address.