Understanding IPv6 Addressing

Subnetting and Supernetting

• Subnetting divides a large network into smaller subnets for better organization and usage of IP addresses, enhancing security and performance.
• The Network Address is the first IP address in a subnet, while Host Addresses are the usable addresses assigned to devices between the Network and Broadcast Addresses.
• The Broadcast Address is the last IP address in a subnet.
• Supernetting combines multiple smaller subnets into a larger network, streamlining management for ISPs and organizations by reducing the number of subnet allocations.
• Example of supernetting: Four Class C networks (192.168.0.0/24 to 192.168.3.0/24) can be combined into a single supernet (192.168.0.0/22) covering IPs from 192.168.0.0 to 192.168.3.255.

Switches and VLANs

• Switches connect multiple devices within a Local Area Network (LAN) and operate at the data link layer (Layer 2), forwarding data frames using MAC addresses.
• VLANs (Virtual Local Area Networks) partition a single physical switch into several logical, isolated networks, improving security and reducing broadcast domains.
• In a corporate environment, VLANs can separate departments (e.g., HR, Finance) to manage traffic and security better.
• VLANs can help reduce broadcast traffic in large networks, such as university campuses, by creating smaller broadcast domains.
• Improved flexibility allows easy reassignment of switch ports to different VLANs without re-cabling.
• Privileged EXEC mode on Cisco devices allows full access to system settings, while Configuration mode is used for system-wide changes like setting up VLANs.

IPv6 Overview

• IPv6 is a 128-bit address system using hexadecimal characters, developed to address IPv4 address exhaustion.
• Introduced in 1998 and standardized in 2017, IPv6 provides vastly more addresses (2^128) compared to IPv4's 32-bit address space (2^32).
• IPv6 addresses are formatted as eight blocks of 16 bits separated by colons, unlike IPv4's decimal format.
• Subnetting in IPv6 uses slash notation (e.g., /64) rather than traditional subnet masks.

Address Types and Formats

• Public IP addresses are globally unique and accessible over the internet, while Private IP addresses are used within local networks and are not routable on the internet.
• IPv6 addresses include various types:
  • Unicast: For single device communication.
  • Loopback Address: Represented as ::1, it sends packets to the own device.
  • Link-local Address: For communication within a single link, not routable outside the link.
  • Unique Local Unicast Address (ULA): Equivalent to IPv4 private addresses, beginning with FD00::/8 or FC00::/8.
  • Global Unicast Address (GUA): Equivalent to public addresses for internet use, ranges between 2000 and 3FFF.
  • Unspecified Address: Denotes the absence of an address, represented as ::.

Multicast Addresses

• IPv6 multicast addresses enable one-to-many communication efficiently, starting with FF.
• Examples of well-known multicast addresses include:
  • FF02::1: All nodes on the local link.
  • FF02::2: All routers on the local link.
  • FF02::5: For routers running OSPFv3, a routing protocol for IPv6.