Introduction

6RD tunnels IPv6 traffic over IPv4 backbone. It is mainly targeted from service providers.

6RD Overview

6RD stands for Rapid Deployment as initials of its inventor Remi Despres.
Architecturally it has two components: 6RD CE and 6RD BR (Border Relay)
6 RD CE encapsulated IPv6 native packets over IPv4 to traverse the IPv4 only backbone. It is a dual stack device.
Encapsulation is based on IPv6-in-IPv4 tunnel using protocol IP Protocol 41.
6 RD BR decapsulates the packets to the edge of the network connected to native IPv6 internet.
The CE will either encapsulate IPv6 and send it to the BR or another CE, depending on the configure IPv6 6rd domain prefix.
The IPv6 address is similar to 6to4 where the IPv4 address is embedded into the IPv6 address. The major difference and advantage is that 6RD doesn't use a well-know 6to4 prefix (2002::/16) but uses the provider's addressing.
Within the 6RD addressing an IPv4 address of the destination tunnel is embedded.
Internal addressing (CE to CE IPv6 traffic), can use what's called IPv4 common prefix and IPv4 common suffix
- IPv4 common prefix
- IPv4 common suffix

Address allocation can be done with DHCP.
Border Gateways IPv4 address are usually advertised as anycast addresses for redundancy and simplification