Due to the exhaustion of IPv4 addresses, IPv6 was developed. It consists of eight groups of four hexadecimal digits separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). IPv6 addresses are 128-bit numbers, allowing for a vastly larger number of unique addresses.
Exact Number of IPv6 addresses: 340, 282, 366, 920, 938, 463, 463, 374, 607, 431, 768, 211, 456, 340, 282, 366, 920, 938, 463, 463, 374, 607, 431, 768, 211, 456, 340, 282, 366, 920, 938, 463, 463, 374, 607, 431, 768, 211, 456
IPv6 does not have the concept of address classes (like IPv4’s Class A, B, C, etc.) due to its large address space and different addressing architecture. Instead, IPv6 addresses are categorized based on their prefix and intended use. Here’s a table summarizing the different types of IPv6 addresses:
IPv6 Address Type Details
| Address Type | Range/Prefix | Purpose and Notes |
|---|---|---|
| Unspecified Address | ::/128 | Represents an unknown or unspecified address. Used as a source address when a device is in the process of obtaining an address. |
| Loopback Address | ::1/128 | Used for internal testing on a single device. Equivalent to 127.0.0.1 in IPv4. |
| Global Unicast | 2000::/3 | Publicly routable addresses similar to IPv4 public addresses. Assigned by IANA and distributed by ISPs. |
| Link-Local Unicast | FE80::/10 | Automatically configured addresses for communication within a single local network segment. Not routable beyond the local link. |
| Unique Local Address | FC00::/7 | Similar to IPv4 private addresses. Used for local communication within a site or a limited area. Not routable on the global internet. |
| Multicast Address | FF00::/8 | Used to send packets to multiple destinations. Various scopes defined by the second octet (e.g., FF02::1 for all nodes on the local network segment). |
| Anycast Address | N/A | Anycast addresses are assigned from the same address space as unicast addresses. Packets are delivered to the nearest interface. |
- Global Unicast Addresses: Used for devices that need to be accessible globally. These addresses are unique across the internet.
- Link-Local Addresses: Automatically assigned to interfaces and used for local communication within a network segment. They are not routable outside the local network.
- Unique Local Addresses (ULA): Used for local communication within private networks. They provide a way to address devices without using global unicast addresses.
- Multicast Addresses: Used for one-to-many communication, where packets are delivered to all interfaces that have joined the multicast group.
- Anycast Addresses: Assigned to multiple interfaces, but packets sent to an anycast address are routed to the nearest interface based on routing metrics.
IPv6’s addressing architecture allows for more flexible and scalable network designs, addressing the limitations and complexities of IPv4.
Key Features and Benefits of IPv6
- Larger Address Space:
- Address Length: IPv6 addresses are 128 bits long, compared to 32 bits in IPv4.
- Total Addresses: IPv6 supports approximately 3.4 x 10^38 (340 undecillion) unique addresses, ensuring ample address space for the foreseeable future.
- Address Format:
- Representation: IPv6 addresses are written as eight groups of four hexadecimal digits, separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).
- Compression: Leading zeros in each group can be omitted, and consecutive groups of zeros can be replaced by a double colon (::), but only once per address (e.g., 2001:db8::8a2e:370:7334).
- Simplified Header:
- The IPv6 header is streamlined for efficient processing. It has a fixed length of 40 bytes, reducing the overhead for routers.
- Key Fields: Includes version, traffic class, flow label, payload length, next header, hop limit, source address, and destination address.
- Built-in Security:
- IPsec: Security features for authentication, data integrity, and confidentiality are mandatory in IPv6, whereas they are optional in IPv4.
- No Need for NAT (Network Address Translation):
- The vast address space eliminates the need for NAT, enabling end-to-end connectivity and simplifying network design.
- Address Autoconfiguration:
- Stateless Address Autoconfiguration (SLAAC): Allows devices to automatically configure their own IP addresses without the need for a DHCP server.
- DHCPv6: Also available for stateful address configuration and additional configuration details.
- Improved Multicast and Anycast:
- Enhanced support for multicast (one-to-many) and anycast (one-to-nearest) addressing, improving the efficiency of data distribution.
- Simplified Network Configuration:
- Larger address space and hierarchical address allocation facilitate more efficient and scalable routing.
- Extensible Protocol:
- IPv6 allows for future growth and new features through the use of extension headers, which provide optional information without impacting the main header.