6.5 IPv6

Question 1

IPv6

Answer 1

Internet Protocol version 6 or IPv6.

IPv6 addresses are 128 bits in size.

IPv6 addresses are just 128-bit binary numbers.

IPv6 addresses are usually written out as eight groups of 16 bits each.
Each one of these groups is further made up of four hexadecimal numbers.

Question 2

2001:0db8

Answer 2

2001:0db8 has been reserved for documentation and education or for books and courses just like this one.

Question 3

There are two rules when it comes to shortening an IPv6 address.

Answer 3

The first is that you can remove any leading zeros from a group.
The second is that any number of consecutive groups composed of just zeros can be replaced with two colons.
I should call out that this can only happen once for any specific address.

Question 4

LOOPBACK ADDRESS

Answer 4

With IPv6, the loopback address is 31 zeros with a one at the end, which can be condensed all the way down to just::1.

Question 5

MULTICAST

Answer 5

FF00: : is used for multi-cast, which is a way of addressing groups of hosts all at once.

Question 6

LINK LOCAL UNICAST

Answer 6

Link-local unicast addresses allow for local network segment communications and are configured based upon a host’s MAC address.

The link-local address are used by an IPv6 host to receive their network configuration.

Question 7

NETWORK ID

Answer 7

The first 64 bits of any IPv6 address is the network ID.

Question 8

HOST ID

Answer 8

The second 64 bits of any IPv6 address is the host ID.

Question 9

IPv6 SUBNETTING

Answer 9

IPv6 subnetting uses the same cider notation that you’re already familiar with.
This is used to define a sub-net mask against the network ID portion of an IPv6 address.

Question 10

1 VERSION FIELD

Answer 10

The version field is a 4-bit field that defines what version of IP is in use.

Question 11

2 TRAFFIC CLASS FIELD

Answer 11

Is an 8-bit field that defines the type of traffic contained within the IP datagram and allows for different classes of traffic to receive different priorities.

Question 12

3 FLOW LABEL FIELD

Answer 12

Is a 20-bit field that’s used in conjunction with the traffic class field for routers to make decisions about the quality of service level for a specific datagram.

Question 13

4 PAYLOAD LENGHT FIELD

Answer 13

This is a 16-bit field that defines how long the data payload section of the datagram is.

Question 14

5 NEXT HEADER FiELD

Answer 14

IPv6 addresses are four times as long as IPv4 addresses. That means they have more ones and zeros which means that they take longer to transmit across a link. To help reduce the problems with additional data that IPv6 addresses impose on the network, the IPv6 header was built to be as short as possible. One way to do that is to take all of the optional fields and abstract them away from the IPv6 header itself.

Question 15

6 NEXT HEADER FIELD

Answer 15

The next header field defines what kind of header is immediately after this current one. These additional headers are optional, so they’re not required for a complete IPv6 datagram. Each of these additional optional headers contain a next header field and allow for a chain of headers to be formed if there’s a lot of optional configuration.

Question 16

7 HOP LIMIT FIELD

Answer 16

This is an 8-bit field that’s identical and purpose to the TTL field in an IPv4 header.

Question 17

8 SOURCE ADDRESS FIELD

Answer 17

128 bits

Question 18

9 DESTINATION ADDRESS FIELD

Answer 18

128 bits

Question 19

10

Answer 19

If the next header field specified another header, it would follow at this time. If not, a data payload, the same length as specified in the payload length field would follow.

Question 20

IPv4-mapped address space

Answer 20

The IPv6 specifications have set aside a number of addresses that can be directly correlated to an IPv4 address. Any IPv6 address that begins with 80 zeros and is then followed by 16 ones, is understood to be part of the IPv4-mapped address space. The remaining 32 bits of the IPv6 address is just the same 32 bits of the IPv4 address it’s meant to represent.

Question 21

IPv6 tunnels

Answer 21

They consist of IPv6 tunnels servers on either end of a connection. These IPv6 tunnels servers take incoming IPv6 traffic and encapsulate it within traditional IPv4 datagrams. This is then delivered across the IPv4 Internet space, where it’s received by another IPv6 tunnel server. That server performs the D encapsulation and passes the IPv6 traffic further along the network.

Question 22

IPv6 tunnel broker

Answer 22

Companies that provide IPv6 tunneling endpoints for you, so you don’t have to introduce additional equipment to your network.