With a derivative of 6to4 is one of the

With the need for more IP addresses, the transition from IPv4 to IPv6 has taken a rampant pace. More and more service providers are looking for best and economical way to provision IPv6 addresses to their customers. IPv6 Rapid Deployment (6rd), a derivative of 6to4 is one of the most economical solution for the providers to deploy IPv6 using their pre-existing IPv4 core infrastructure. The technology was introduced and deployed by a French ISP, Free Telecom in 2007. Built over 6to4, 6rd exploits service providers own IPv6 address prefix rather than a standardized prefix of 2002: :/16 in 6to4. Through 6rd the IPv6 hosts can communicate with each other by establishing an IPv4 tunnel. The technology relies on encapsulating the IPv6 traffic within IPv4 packets at one end of the tunnel towards the sender which are transmitted to the receiver over an IPv4 infrastructure. At the other end of the tunnel towards receiver’s end, the packets are decapsulated and are sent over IPv6 network to their respective destination. To deploy 6rd, service provider needs two main hardware components: 6rd Customer Equipment/Edge (CE) and 6rd Border Relay (BR), as shown in Figure 1. CE is deployed at the customer’s end while BR at ISP’s IPv4 infrastructure edge, acting as an encapsulator and decapsulator respectively. If a packet has an IPv6 destination address under another ISP network, it must pass through the BR. However, if it’s destined to an address within the same ISP, the packet is routed internally. Since all the 6rd devices communicate with each other through their IPv4 addresses, the tunneled traffic follows the IPv4 routing protocol. As shown in figure 1, each customer site is connected to a CE which is pre-configured with 6rd Delegated prefix which is a combination of 6rd Prefix and the router’s IPv4 address (all or part of it). The 6rd prefix is unique to a service provider obtained during registry. Figure 2 shows the rest of the part of 6rd address consisting of Subnet ID and Interface ID. As all these devices, CE and BR within a 6rd domain will have same 6rd prefix with their own IPv4 address appended. Subnet ID will help to differentiate between the subnets, while the Interface ID is obtained from hosts MAC address. Figure 2 6rd address format Besides being economical and easy solution to provision IPv6, 6rd provides some additional advantages for example, through 6rd subscribers can easily get access to IPv6, there are several vendors available to quickly provide 6rd Figure 1 IPv6 Rapid Deployment (6rd) Border relay and CE routers, & the most important is the stateless operation of 6rd, as it does not carry the drawbacks of 6to4. Nevertheless, 6rd is not a long-term solution to provision IPv6. Firstly, CE routers needs to be upgraded to support 6rd, also the service provider has to deploy one or more border relay routers. Lastly, 6rd does not allow IPv6 clients to communicate to IPv4 servers, in-order to do so techniques like NAT64/ SLB64 are vital.