# IPv6 in IPv4 Tunneling

IPv6 in IPv4 tunneling is a method for transmitting IPv6 packets over IPv4 networks. Using this method, the NetScreen device encapsulates outgoing IPv6 packets inside of IPv4 packets or decapsulates such packets when they are incoming.

Note: Use IPv6 in IPv4 tunneling as a relatively simple transition mechanism, when it is not necessary to perform IPSec operations such as authentication and encryption on exchanged traffic. For example, your organization might need to exchange traffic between island IPv6 networks over an IPv4 WAN, using the NetScreen device for firewall services only.

IPv6 in IPv4 Tunneling Encapsulation Settings: Enables the interface for IPv6 over IPv4 tunneling.

Local Interface: The interface through which the NetScreen device sends service requests to the remote server.

IPv6 over IPv4 6to4 tunneling: Enables the interface for 6to4 tunneling (described below).

IPv6 over IPv4 manual tunneling: Enables the interface for manual tunneling (described below).

Destination IP Address: The address of the remote IPv4 remote-end tunnel termination point.

## 6to4 Tunneling

6to4 tunneling determines remote-end tunnel termination points (gateways) dynamically. In contrast with manual tunneling, which explicitly designates a single termination point, 6to4 tunneling can allow any number of devices to serve as remote gateways. This allows one-to-many communication between a protected island IPv6 network and multiple external IPv6 networks.

## Manual Tunneling

Manual tunneling uses a manually configured, static remote-end tunnel termination point. Because a manual tunnel exists between two fixed, defined end points, it is better suited for applications that require strict control. Such tunnels usually provide more security than 6to4 tunneling.