The application mode of IPV6 ISATAP tunnel and 6to4 tunnel

Tunneling technology is a very important application in IPV6 transition technology. Depending on how the IPv4 address of the tunnel endpoint is obtained, the tunnel is divided into "manual tunneling" (or "Configuration Tunnel") and "Automatic Tunneling". Compared with manual tunnels, automatic tunnels are more flexible in configuration and use. While the ISATAP tunnel and the 6to4 tunnel are two common automatic tunnels, this paper describes the application modes of these two tunnels.

The specific configuration involved in the article can be realized on the IPV6 device provided by H3C.

1.ISATAP Tunnel

1.1 Feature Introduction

With the popularization of IPV6 technology, more and more IPV6 hosts will appear in the existing IPV4 network, ISATAP Tunnel technology provides a better solution for this kind of application. ISATAP Tunnel is a point-to-point automatic tunneling technique, which can automatically obtain the end point of the tunnel by embedding the IPV4 address in the destination address of the IPV6 message.

When using the ISATAP tunnel, the destination address of the IPV6 message and the IPV6 address of the tunnel interface are addressed with a special address: ISATAP address. The ISATAP address format is: Prefix (64bit): 0:5efe:ipv4addr (Ipv4addr is the IPV4 source address of the tunnel endpoint, in the form of a.b.c.d or xxxx:xxxx, where xxxx: XXXX is a 32-bit IPV4 source address a.b.c.d conversion from the 32-bit 16 binary representation). Through this embedded IPV4 address, the tunnel can be automatically built to complete the transmission of IPV6 message.

Figure 1. Address format for ISATAP tunnels

The ISATAP tunnel can be used to IPV6 routers-ipv6 routers, host-router connections in a IPV4 network. Since the tunnel node is not required to have a globally unique IPV4 address, it can be used for IPv6 communication between the two stack hosts in the internal private network. So the ISATAP tunnel is suitable for communication between IPV6 hosts in the IPV4 network or IPV4 communication of IPV6 hosts to IPV6 networks in the network (as shown in the following illustration).

Figure 2. ISATAP Tunnel application of host-router

1.2 Network Application Mode

In the early stage of IPV6 network construction, for investment consideration, it may be difficult to realize the original IPV4 network upgrade to the Ipv6/ipv4 double stack mode, so more use will be the convergence of the site or export equipment (such as routers) first upgrade to the dual stack mode, and the convergence layer equipment below still maintain the original IPV4 network. In order to realize the communication between the two-stack host and other IPV6 network located in the IPV4 resident network, or IPv6 the communication between the hosts, the ISATAP host-Router tunnel deployment mode can be adopted.

Figure 3. Host-router ISATAP tunnel Configuration Example