IPv6 in AWS

Why IPv6?

• IPv4 supports ~4.3 billion addresses, now largely exhausted.

• IPv6 provides 3.4 × 10³⁸ unique addresses, ensuring long-term scalability.

Key Characteristics in AWS

• All IPv6 addresses are public and internet-routable; no private IPv6 ranges exist.

• Operates in dual-stack mode — IPv4 cannot be disabled for VPCs or subnets.

• Format: 8 hexadecimal segments (0000–ffff) separated by colons :.
• Example: 2001:db8:3333:4444:5555:6666:7777:8888
• Shortening: :: for consecutive zeros (2001:db8::1234:5678).

EC2 Addressing

• Each instance receives:
• Private IPv4 (internal use).
• Public IPv6 (internet-routable).

• Internet access:
• IPv4 → via NAT Gateway or Internet Gateway.
• IPv6 → directly via Internet Gateway (no NAT required).

Benefits

• Massive, globally unique address space.

• Simplified internet routing for IPv6 traffic.

• Enables modern application architectures requiring public reachability without NAT.