modul12-IPv6 Addressing: Key Concepts and Types

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Questions and Answers

What is one significant advantage of IPv6 over IPv4?

IPv6 uses 32-bit addresses like IPv4.

IPv6 can only be used locally.

IPv6 has a vast address space. (correct)

IPv6 allows for NAT complexity.

Which format is used to represent an IPv6 address?

32 binary digits separated by dots.

8 hextets expressed as hexadecimal digits. (correct)

16 bits grouped in pairs and connected by colons.

128 octets grouped with symbols.

Which type of IPv6 address is designed for local subnet communication?

Link-Local Address (correct)

Unique Local Address

Anycast Address

Global Unicast Address

How does the Global Unicast Address (GUA) typically start?

2000::/3 Signup and view all the answers

Which method is NOT used to create the 64-bit Interface ID in an IPv6 address?

NAT adaptations Signup and view all the answers

What is the purpose of the double colon (::) in an IPv6 address?

To omit leading zeros in contiguous all-0 hextets. Signup and view all the answers

What is the typical prefix size for subnetting in a Global Unicast Address?

/64 Signup and view all the answers

What role does the Solicited-Node multicast address play?

It facilitates neighbor discovery. Signup and view all the answers

What is the primary purpose of a link-local address (LLA) in IPv6?

To facilitate local link communication. Signup and view all the answers

What does the SLAAC+Stateless DHCPv6 method provide to a device?

GUA and DNS/domain information. Signup and view all the answers

Which command would provide a summary of IPv6 addresses on interfaces in a Cisco environment?

show ipv6 interface brief Signup and view all the answers

What is the maximum number of subnets that can be created from a /48 assigned IPv6 address?

65536 Signup and view all the answers

Which of the following methods requires a stateful DHCPv6 server for obtaining an IPv6 address?

Stateful DHCPv6 only Signup and view all the answers

Which of the following statements regarding the EUI-64 method is true?

EUI-64 uses a 64-bit number created from a MAC address. Signup and view all the answers

What happens when a device receives a Router Advertisement (RA) message on an IPv6 network?

It uses the default gateway specified in the message. Signup and view all the answers

Given an address prefix of 2001:db8:acad::/48, how would the first subnet's address look like?

2001:db8:acad:0000:: Signup and view all the answers

Study Notes

IPv6 Addressing: Key Concepts

Why IPv6?
- IPv4 address exhaustion is a major concern, limiting future growth and IoT device integration.
- IPv6 drastically expands the address space, eliminating the need for NAT.
- IPv4 and IPv6 coexistence is essential, and transition methods (dual stack, tunneling, translation) are used for smooth integration.

IPv6 Address Representation

Format: IPv6 addresses are 128 bits, represented as 8 hextets (16-bit blocks) in hexadecimal format (xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx).
Rules: Leading zeros are omitted, and contiguous blocks of zeros can be represented as double colons, "::", but only one can be used.

IPv6 Address Types

Unicast: Address for a single device.
- Global Unicast (GUA): Globally unique and internet-routable; typical prefix is 2000::/3. Typically has /64 prefixes (initial 64 bits for network, final 64 bits for interface ID).
- Link-Local (LLA): Addresses used for communication within a local network (fe80::/10).
- Unique Local: Private addresses (fc00::/7 to fdff::/7); not globally routable.
- Loopback: ::1 (used for self-communication).
- Unspecified: :: (all zeros).
Multicast: Address for multiple devices (a group).
- Assigned/Well-known Multicast: Addresses like ff02::1 (all-nodes) and ff02::2 (all-routers).
- Solicited-Node Multicast: ff02::1:ffxx:xxxx. Used for Neighbor Discovery.
Anycast: Address assigned to multiple devices, but packets are routed to the "nearest" one (beyond scope).

IPv6 Global Unicast Addresses (GUAs)

Format: GUAs are split into Global Routing Prefix (assigned by ISP), Subnet ID (for organizing subnets within an organization; commonly 16 bits for a /48 prefix allowing up to 65,536 subnets), and Interface ID (typically 64 bits allowing massive host capacity).

Creating the Interface ID

EUI-64: Method for generating interface ID from a 48-bit MAC address. It modifies the MAC address by inserting "fffe" and flipping the seventh bit.
Randomly Generated: Windows often uses this for increased privacy, generating a random 64-bit number.

Obtaining the IPv6 GUA

Autoconfiguration (SLAAC): Automatic address configuration.
Stateless DHCPv6: SLAAC for GUAs and default gateway; obtaining DNS and domain info from a stateless DHCPv6 server.
Stateful DHCPv6: Obtaining the GUA and other configuration parameters from a stateful DHCPv6 server. Default gateway is learned from the RA's source (the router's link-local address).

Link-Local Addresses (LLAs)

Every IPv6 interface must have a LLA (in fe80::/10 range).
Used for communication within a network link.
Created statically, or dynamically. Routers use LLAs as next-hop addresses, and hosts use a router's LLA as the default gateway.

IPv6 Subnetting

Unlike IPv4, IPv6 subnets are denoted directly within the address (e.g., /64).
If assigned a /48 prefix (e.g., 2001:db8:acad::/48), there are 16 bits remaining for subnet ID (allowing up to 65,536 subnets) with each having a potential 2⁶⁴ hosts. Subnet IDs are expressed in hexadecimal increments.

Verifying IPv6 Configuration

Cisco IOS:
- show ipv6 interface brief: Displays IPv6 addresses on interfaces (including GUAs and LLAs).
- show ipv6 route: Shows the IPv6 routing table.
- show ipv6 interface: Provides detailed information about a specific interface (IPv6 address).
Windows:
- ipconfig: Displays assigned IPv6 addresses, including link-local addresses, GUAs, and the default gateway address.

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Description

This quiz explores the fundamental concepts of IPv6 addressing, including its necessity due to IPv4 exhaustion, address representation, and various address types. Test your knowledge on the structure and rules governing IPv6, as well as its coexistence with IPv4.