IPv6 transition technologies
ISATAP (Intra-Site Automatic Tunneling Address Protocol)
ISATAP is designed to transport IPv6 packets between dual-stack nodes on top of an IPv4 network. It treats the IPv4 network as a link layer for IPv6 and uses IPv4 as a virtual non-broadcast multiple-access (NBMA) network.
- It can be implemented without the need for dedicated IPv6 routers or hardware.
- It’s not recommended for use across the internet or between sites because of its lack of support for IPv4 Network Address Translation (NAT) and other issues.
A dual-stack network is designed to maintain both IPv4 and IPv6 addresses, which allows devices to operate either IPv4 and IPv6 concurrently.
- It provides a straightforward approach to support both versions and is very useful during the transition period from IPv4 to IPv6.
- It allows for native connectivity to both IPv4 and IPv6 networks.
- It essentially requires double the configuration and management as two separate protocols are being maintained.
- The implementation can be costly as it requires considerable memory and processing power.
6to4 is a tunneling protocol for transitioning from IPv4 to IPv6, automatically assigning an IPv6 prefix to the user, based on the user’s IPv4 address.
- It’s designed for situations where a site wants to start using IPv6 but its ISP doesn’t support it yet.
- The primary disadvantage of 6to4 is its reliance on the reliability of relay routers, which aren’t under the control of the site using 6to4.
- It doesn’t work well with NAT.
- It has been deprecated as a transition mechanism due to various issues like lack of support for IPv4 NATs, and issues related to the use of anycast address for 6to4 Relay Routers.
6rd (IPv6 Rapid Deployment)
6rd is based on 6to4 with modifications to work efficiently with ISPs that have IPv4 infrastructure.
- It provides a way to quickly provide IPv6 connectivity to end users when the ISP is still using IPv4 infrastructure.
- Unlike 6to4, 6rd works well with NAT.
- 6rd is a more complex solution than native IPv6 and will eventually need to be replaced as IPv6 becomes the standard.
- It requires the ISP to maintain a 6rd Border Relay, which can add complexity to the network infrastructure.