• 32‑bit addresses (≈ 4.3 billion unique IDs)
• Written in “dot‑decimal” (e.g. 192.168.1.1)
• Introduced 1983; world’s workhorse for decades
• 128‑bit addresses (≈ 3.4 × 10³⁸ unique IDs)
• Written in colon‑hex (e.g. 2001:0db8::1)
• Standardized 1998 to replace IPv4
| Aspect | IPv4 | IPv6 |
|---|---|---|
| Address length | 32 bits | 128 bits |
| Notation | Decimal octets (x.x.x.x) | Hexadecimal hextets (x:x:…:x) |
| Header complexity | Variable (20–60 bytes) | Fixed (40 bytes) |
| Broadcast | Uses broadcasts | No broadcasts; uses multicast & anycast |
| Address assignment | Manual or DHCP | SLAAC (stateless) & DHCPv6 |
| Fragmentation | Routers and hosts | Hosts only |
| Built‑in security | Optional (IPsec add‑on) | Mandatory support for IPsec |
| Flow identification | Not available | Flow Label field for QoS |