Ch29-IPv6 Addressing and Subnetting

Question 1

A type of unicast IPv6 address that has been allocated from an range of public, globally-unique IP addresses, as registered through IANA/ICANN, its member agencies, and other registries or ISPs

Answer 1

global unicast address

Question 2

An IPv6 prefix that defines an IPv6 address block made up of global unicast addresses, assigned to one organization, so that the organization has a block of globally unique IPv6 addresses to use in its network

Answer 2

global routing prefix

Question 3

A type of IPv6 unicast address meant as a replacement for private IPv4 IP addresses

Answer 3

unique local address

Question 4

The number that represents the ipv6 subnet, also known as the IPv6 prefix, or, more formally, the subnet router any cast address

Answer 4

subnet ID (or prefix ID)

Question 5

A special anycast address in each IPv6 subnet, reserved for use by routers as a way to send a packet to any router on the subnet. The address’s value in each subnet is the same as the subnet ID

Answer 5

subnet router anycast address

Question 6

Describe the EUI-64 process

Answer 6

The eui-64 process is a method used to derive unique interface ID for global unicast, unique local, and link-local IPv6 address. The process requires: 1. Splitting the MAC address at the 24th bit boundary 2. Inserting hex FFFE 3. Inverting the 7th bit of the MAC address The resulting 64 bit value is added to the provided prefix, resulting in a complete IPv6 address

Question 7

An IPv6 address is configured on a working interface. What functions does a router enable once this occurs?

Answer 7

1. Gives the interface a unicast IPv6 address 2. Enables routing of packets in/out of that interface 3. Defines the subnet that now exists off that interface 4. Adds connected IPv6 route to the routing table

Question 8

What is the forwarding scope of a link-local IPv6 address.

Answer 8

Forwarding scope is link-local only; routers will not route packets destined to a link-local address to other links.

Question 9

Are link-local addresses classified as unicast or multicast?

Answer 9

unicast

Question 10

Link-local addresses might be automatically generated by a host; what function does this serve?

Answer 10

Solves some initialization problems before the host has global unicast address

Question 11

By definition, the first 10 bits of link-local addresses match FE80::/10 — what possible values could be expected for a link-local prefix?

Answer 11

Prefixes beginning with: FE8 FE9 FEA FEB

Question 12

The prefix of an IPv6 link-local address will be FE80::/10, with the next 54 bits expressed as binary 0. How is the interface ID of a link-local addresses derived?

Answer 12

It may be manually configured or automatically generated, including by EUI-64

Question 13

What are common uses for link-local addresses?

Answer 13

1. overhead protocols within the subnet 2. next-hop address for IPv6 routers

Question 14

When does Cisco IOS create a link-local address for an interface?

Answer 14

Any time an interface has an IPv6 unicast address configured on it

Question 15

The fist hex digits of a given IPv6 address are 2 or 3; what type of address does this imply?

Answer 15

global unicast

Question 16

The fist hex digits of a given IPv6 address are FD; what type of address does this imply?

Answer 16

unique local

Question 17

The fist hex digits of a given IPv6 address are FF; what type of address does this imply?

Answer 17

multicast

Question 18

The first hex digits of a given IPv6 address are FE80::/10; what type of address does this imply?

Answer 18

link-local

Question 19

In designing a new subnet for an IPv6 network, it’s determined that the subnet needs to utilize unique local addressing. Describe the process for generating a unique local address.

Answer 19

1. Use FD as first 2 hext digits (8 bits)
2. Choose unique 40-bit global ID (random process!)
3. Combine 1&2 to obtain prefix
4. Use next 16 bits as subnet field
5. The remaining 64 bits are available as interface ID