====== IPv6 ======

**IPv6 (Internet Protocol version 6)** is the successor to IPv4. It was developed to overcome the limited address space of IPv4 while simplifying many aspects of Internet routing and network configuration.

An IPv6 address is **128 bits** long, providing an extremely large number of unique addresses.

Example:

<code>
2001:db8:85a3::8a2e:370:7334
</code>

Today, IPv6 is increasingly deployed alongside IPv4 across the Internet.

-----

===== Why Was IPv6 Developed? =====

IPv4 uses 32-bit addresses, allowing approximately:

<code>
2^32

=

4.3 billion addresses
</code>

As the Internet grew, this address space became insufficient.

IPv6 was introduced to provide:

  * A vastly larger address space
  * Improved routing efficiency
  * Simplified network configuration
  * Better support for modern Internet applications

-----

===== IPv6 Address Format =====

An IPv6 address contains **128 bits**, written as eight groups of four hexadecimal digits.

Example:

<code>
2001:0db8:85a3:0000:0000:8a2e:0370:7334
</code>

Each group represents 16 bits.

Hexadecimal digits use:

<code>
0-9
A-F
</code>

-----

===== Address Compression =====

IPv6 provides rules that make addresses easier to read.

Leading zeros may be omitted:

<code>
2001:0db8:0000:0000:0000:0000:0000:0001

↓

2001:db8:0:0:0:0:0:1
</code>

One consecutive sequence of zero groups may be replaced by "::"

<code>
2001:db8:0:0:0:0:0:1

↓

2001:db8::1
</code>

The "::" shortcut may appear only once in an IPv6 address.

-----

===== Address Space =====

IPv6 provides:

<code>
2^128

≈

340 undecillion addresses
</code>

This number is so large that IPv6 effectively eliminates address exhaustion for the foreseeable future.

-----

===== Common IPv6 Address Types =====

^ Prefix ^ Purpose ^
| 2000::/3 | Global Unicast |
| fc00::/7 | Unique Local Addresses (ULA) |
| fe80::/10 | Link-Local Addresses |
| ::1 | Loopback |
| :: | Unspecified Address |

-----

===== Global and Unique Local Addresses =====

=== Global Unicast ===

These are publicly routable on the Internet.

Example:

<code>
2001:4860:4860::8888
</code>

-----

=== Unique Local Addresses (ULA) ===

These are similar to private IPv4 addresses.

Example:

<code>
fd12:3456:789a::1
</code>

They are intended for use within private networks.

-----

===== Link-Local Addresses =====

Every IPv6-enabled interface automatically receives a **link-local address**.

These addresses begin with:

<code>
fe80::
</code>

They are used for communication within the local network segment and are never routed across the Internet.

-----

===== IPv6 Does Not Usually Require NAT =====

One major difference from IPv4 is that IPv6 generally provides enough addresses for every device to have its own globally unique address.

Therefore, **Network Address Translation (NAT)** is usually unnecessary.

This simplifies end-to-end communication.

-----

===== IPv4 vs IPv6 =====

^ IPv4 ^ IPv6 ^
| 32 bits | 128 bits |
| Decimal notation | Hexadecimal notation |
| About 4.3 billion addresses | Vast address space |
| NAT commonly used | NAT usually unnecessary |
| Broadcast supported | No broadcast (uses multicast instead) |

-----

===== Dual Stack =====

Many modern networks support both IPv4 and IPv6 simultaneously.

This is known as **Dual Stack**.

Example:

<code>
IPv4

203.0.113.25

IPv6

2001:db8::25
</code>

A device may communicate using either protocol depending on network availability.

-----

===== Reverse DNS =====

IPv6 supports Reverse DNS using the **ip6.arpa** namespace.

Example:

<code>
2001:db8::1

↓

...ip6.arpa
</code>

Reverse DNS is implemented using PTR records, just as with IPv4.

-----

===== IPv6 and Telenegar =====

Several Telenegar tools support IPv6 addresses.

  * [[tools:ipcheck|IP Check]]
  * [[tools:pingcheck|Ping Check]]
  * [[tools:traceroute|Traceroute]]
  * [[tools:portcheck|Port Check]]

These tools can display information such as:

  * Public or private status
  * Reverse DNS (PTR)
  * ASN
  * Geolocation
  * Network ownership

-----

===== Common Misconceptions =====

  * **IPv6 replaces IPv4 overnight.**
    * False. Most networks currently operate both protocols simultaneously.

  * **IPv6 is simply a longer IPv4 address.**
    * False. IPv6 introduces new addressing methods and networking concepts.

  * **IPv6 requires NAT.**
    * False. NAT is generally unnecessary because of IPv6's enormous address space.

-----

===== Related Topics =====

  * [[networking:internet:ip-addresses|IP Addresses]]
  * [[networking:internet:ipv4|IPv4]]
  * [[networking:internet:private-public|Private vs Public IP]]
  * [[networking:dns:reverse-dns|Reverse DNS]]
  * [[tools:ipcheck|IP Check]]

-----

{{tag>ipv6 ip internet networking ip6 dual-stack}}