chapter 12 CNT

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

How do we represent IPv6 addresses?

An IPv6 address is represented as eight groups of four hexadecimal digits, each group representing 16 bits (two octets, a group sometimes also called a hextet). The groups are separated by colons (:).

What is the Global Routing Prefix and how do we get it?

Global Routing Prefix: The Global Routing Prefix is the prefix or network portion of the address assigned by the provider, such as an ISP, to the customer site. Subnet ID: The Subnet ID is a separate field for allocating subnets within the customer site.Oc

What is the prefix of an IPv6 multicast address?

ff00::/ An IPv6 multicast address defines a group of devices known as a multicast group. IPv6 multicast addresses use the prefix ff00::/8, shown in Table 4-10, which is equivalent to the IPv4 multicast address 224.0. 0.0/4. A packet sent to a multicast group always has a unicast source address.

What is this address ff02::2?

ff02::2 All-routers multicast group - This is a multicast group that all IPv6 routers join. A router becomes a member of this group when it is enabled as an IPv6 router with the ipv6 unicast-routing global configuration command If you see an address that is fffe what does that tell us?

GUA

- This is similar to a public IPv4 address. These are globally unique, internet-routable addresses

How long is an IPv6 address?

128 bits An IPv6 address consists of 128 bits (as opposed to the 32-bit size of IPv4 addresses) and is expressed in hexadecimal notation.

NS

A Neighbor Solicitation (NS) message is sent by a node to determine the link-layer address of a neighbor, or to verify that a neighbor is still reachable via a cached link-layer address. NSes are also used for Duplicate Address Detection (DAD).

ANDing

A logical process of combining bits. A bit with a value of 1 plus another bit with a value of 1 results in a 1. A bit with a value of 0 plus any other bit results in a 0.

What is a unicast address and typically how many does each device have?

A unicast address uniquely identifies a single interface by its address. An interface can have multiple unicast addresses and must have at least one link-local address. A link-local address is an address used on a link between two nodes.

What does this command do "ipv6 unicast-routing"?

Cisco routers do not have IPv6 routing enabled by default. To configure IPv6 on a Cisco routers, you need to do two things: enable IPv6 routing on a Cisco router using the ipv6 unicast-routing global configuration command. This command globally enables IPv6 and must be the first command executed on the router.

DHCPv6

DHCP service for managing IPv6 addresses

What type of address is supported by IPv4 but not IPv6?

IPv4 supports broadcast whereas IPv6 doesn't support broadcast. IPv4 supports VLSM (Virtual Length Subnet Mask) whereas IPv6 doesn't support VLSM. IPv4 uses ARP (Address Resolution Protocol) to map to MAC address whereas IPv6 uses NDP (Neighbour Discovery Protocol) to map to MAC address

What is Dual Stack, Tunneling and Translation forms of?

One is dual stack, where your network hardware runs IPv4 and IPv6 simultaneously. The second one is tunnel, meaning encapsulating IPv6 packets within IPv4 packets. And the last method is called Network Address Translation (NAT) by which a device translates IPv6 packets into IPv4 packets or vice versa

What are the rules for shorting an IPv6 address?

One way to shorten IPv6 addresses is to omit leading 0s in any hextet (that is, 16-bit section). This rule applies only to leading 0s and not to trailing 0s; being able to omit both leading and trailing 0s would cause the address to be ambiguous

RA

Router Advertisement (RA) messages are sent by routers to inform hosts on how to obtain an IPv6 GUA and provide useful network information such as:

RS

Router Solicitation (RS) messages are sent by host devices to discover IPv6 routers

DAD

The IPv6 Duplicate Address Detection (DAD) feature ensures that all the IP addresses assigned on a particular segment are unique. The process operates when IPv6 hosts directly communicate with one another where hosts cannot communicate directly, and a proxy is required.

What is a prefix in IPv6?

The leftmost fields of the IPv6 address contain the prefix, which is used for routing IPv6 packets. IPv6 prefixes have the following format: prefix / length in bits. Prefix length is stated in classless inter-domain routing (CIDR) notation.

What do LLA addresses start with?

Thus, link-local addresses are typically described as always starting with 0xfe80. However, section 5.3 of RFC 4862 elaborates on the process used to generate a link-local address: The left-most 'prefix length' bits of the address are those of the link-local prefix.

What is a Link-local address?

Uses fe80::/10 -- specific to the local network, not routable across networks. These addressees are used on a single link. • 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.

What is the most common prefix you will see in IPv6?

a /64 prefix 4.1. Using a /64 prefix from a dedicated pool of IPv6 prefixes is the most common scenario and currently the best practice