¶ 🧮 IPv6 – Internet Protocol Version 6 (Overview)
IPv6 is the most recent version of the Internet Protocol designed to replace IPv4, which is limited to ~4.3 billion unique addresses. IPv6 uses 128-bit addressing, providing virtually unlimited IP addresses for future scalability, IoT, and global connectivity.
¶ 🔢 IPv6 Address Format
An IPv6 address is a 128-bit identifier written in hexadecimal, divided into 8 groups of 4 hex digits, separated by colons (:):
Example: 2001:0db8:85a3:0000:0000:8a2e:0370:7334
You can shorten it using rules:
- Omit leading zeros:
2001:db8:85a3::8a2e:370:7334 - Double colon (:
replaces one or more groups of zeroes (only once per address)
¶ 🧱 IPv6 Address Structure
| Section | Description |
|---|---|
| Global Routing Prefix | Assigned by ISP (identifies the network) |
| Subnet ID | Used to segment networks internally |
| Interface ID | Uniquely identifies a device on a subnet |
¶ 📂 Types of IPv6 Addresses
| Type | Prefix | Description |
|---|---|---|
| Unicast | varies | One-to-one communication |
| Multicast | FF00::/8 |
One-to-many (e.g., router advertisements) |
| Anycast | varies | One-to-nearest in a group (based on routing distance) |
| Link-local | FE80::/10 |
Auto-assigned for devices on the same local link |
| Unique-local | FC00::/7 |
Private addressing (like 192.168.x.x in IPv4) |
| Loopback | ::1 |
Equivalent to 127.0.0.1 in IPv4 |
| Unspecified | :: |
All zeros, used during address assignment |
¶ ⚙️ IPv6 Configuration Options
| Method | Description |
|---|---|
| Stateless Autoconfiguration (SLAAC) | Auto-generates IPv6 address using router advertisements |
| DHCPv6 | Assigns IPv6 addresses via a server (like DHCP in IPv4) |
| Manual | Manually configure static IPv6 addresses |
¶ 🔐 IPv6 Security Notes
- No NAT needed: Every device can have a globally unique IP
- Built-in IPsec: IPv6 was designed with native support for encryption
- Firewalls are essential: Directly addressable devices require filtering
¶ 🔄 IPv4 vs IPv6 Comparison
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address Length | 32-bit | 128-bit |
| Format | Decimal (e.g. 192.168.0.1) | Hexadecimal (e.g. 2001:db8::1) |
| Address Space | ~4.3 billion | 340 undecillion+ |
| NAT Required | Yes | No |
| Built-in Security | Optional (IPsec) | Mandatory support |
| Configuration | DHCP / Static | SLAAC / DHCPv6 / Static |
¶ 🧰 Useful IPv6 Tools
| Tool/Command | Description |
|---|---|
ip a / ip -6 addr |
View IPv6 addresses (Linux) |
ping6 |
Ping using IPv6 |
traceroute6 |
Trace route over IPv6 |
nslookup -query=AAAA |
Check IPv6 DNS records |
netsh interface ipv6 |
Windows IPv6 configuration |
🌍 IPv6 adoption ensures the long-term growth and scalability of the Internet, making it essential for modern network planning and future-proofing infrastructure.