IPv6 Address Cheat Sheet

Understanding IPv6 addresses is essential for network administrators and engineers. Here’s a basic IPv6 address cheat sheet:

IPv6 Address Format

  • Representation:
    • Written in hexadecimal separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).
  • Example Shortened Format:
    • Consecutive blocks of zeros can be replaced with :: once per address (e.g., 2001:0db8::1).

IPv6 Prefix

  • CIDR Notation:
    • Written using the slash followed by the subnet prefix length (e.g., 2001:0db8::/32).

IPv6 Address Types

  • Unicast:
    • Identifies a single interface.
    • Examples: Global unicast, Link-local unicast.
  • Multicast:
    • Sent to multiple interfaces.
    • Examples: FF02::1 (All-nodes), FF02::2 (All-routers).
  • Anycast:
    • Sent to the nearest of a group of addresses.
    • Example: IPv6 addresses assigned to DNS servers.

IPv6 Unique Features

  • Large Address Space:
    • 128-bit address space allows for an enormous number of unique addresses.
  • Global Unicast Addresses:
    • Publicly routable addresses for devices on the Internet.

Loopback Address

  • Loopback:
    • ::1 represents the loopback address (equivalent to IPv4’s 127.0.0.1).

Link-Local Addresses

  • Link-Local Unicast:
    • Automatically assigned on each network interface.
    • Range: fe80::/10

Unique Local Addresses (ULA)

  • Unique Local Unicast:
    • Similar to private addresses in IPv4.
    • Range: fc00::/7

IPv6 Address Allocations

  • Provider Aggregatable (PA) Addresses:
    • Allocated by Internet service providers.
  • Site-Local Addresses (Deprecated):
    • Deprecated in favor of ULA.

Special Addresses

  • Unspecified Address:
    • :: represents the unspecified address.
  • IPv4-Mapped Address:
    • Used in transition scenarios.
    • Example: ::ffff:192.0.2.1

IPv6 Address Notation Rules

  • Hexadecimal Notation:
    • Hexadecimal digits are case-insensitive (e.g., A1b2 is the same as a1b2).
  • Consecutive Zeros:
    • Leading zeros in each block can be omitted.
    • 2001:0db8:0a00::1 can be written as 2001:db8:a00::1.

IPv6 Address Scopes

  • Global Scope:
    • Addresses routable on the global Internet.
  • Link-Local Scope:
    • Limited to a specific network segment.

IPv6 Address Best Practices

  • Use CIDR Notation:
    • Use CIDR notation for address ranges.
  • Document Assignments:
    • Keep detailed documentation of IPv6 address assignments.

IPv6 Address Tools

  • IPv6 Address Calculators:
    • Various online tools available for working with IPv6 addresses.

This cheat sheet provides a quick reference for understanding and working with IPv6 addresses, covering the basics and unique features of the IPv6 addressing scheme.