IPv4 to IPV6 Migration Strategies
- Dual-stack: AKA, Native Mode. Both at the same time. Twice the administrative overhead
- Tunneling: Send the IPv6 packets to tunnel to cross a IPv4 core.
- Translation: Make the IPv6 packets back into IPv4 packets.
- Hybrid Model: Uses ISATAP
- ISATAP: Intra-Site Automatic Tunneling Addressing
- Service Blocks: Combing tunnels with dual-stack.
Native Mode
Both stacks are running on clients. The clients request A and AAAA records near simultaneously.
Whichever DNS records return first decides if the next set of flows are v4 or v6.
This strategy is called “Happy Eyeballs” after the RFC. Do not punish users by “preferring” one protocol or another.
Do whatever is fastest.
Tunneling
- Reduces MTU by 20 bytes.
- The preferred tunnel is GRE.
Automatic Tunnels
6to4
- Uses
2002::/16
6RD
- The ISP uses its own addressing.
ISATAP — Intra-site Automatic Tunnel Addressing Protocol
- Uses these 32 bits to denotes ISATAP
0000:5EFE
Translation
- Much like NAT
DNS64 And NAT64
DNS64
- DNS creates synthetic AAAA records, so a v4 client can connect to a v6 service.
NAT64
- A router translates IPv6 traffic to IPv4 traffic.
References
Happy Eyeballs Version 2: Better Connectivity Using Concurrency