# Engine Editor > Add-Ons > IPv6 Transition Mechanism

Use this dialog to enable IPv6 transition mechanisms that enable communication between devices that have only IPv4 addresses and devices that have only IPv6 address.

Option | Definition
--- | ---
Type | Select one of the following translation modes: NAT64: Allows only IPv6 connectivity to customers while still enabling access to servers that have only IPv4 address. Following fields need to be set: Local IPv4 pools: IPv4 addresses used in translation. NAT64 IPv6 prefix: 32,40,48,56,64 or 96 bit IPv6 prefix. IPv6 addresses matching this prefix will be translated to IPv4 addresses. (96 bit prefix recommended). Static mappings (Optional): Can be used to ensure that specific IPv6 address & port combination will be always translated to specific IPv4 address & port combination. IPv4 address must be from the local IPv4 pool. 464XLAT CLAT: Enables IPv4-only applications to work on IPv6-only networks. Following fields need to be set: Local IPv6 Prefix: 32,40,48,56,64, or 96 bit IPv6 prefix (96 bit prefix recommended) which will be used when translating local IPv4 addresses. Surrounding network must route traffic matching this prefix to Security Engine. Remote IPv6 Prefix: 32,40,48,56,64 or 96 bit IPv6 prefix (96 bit prefix recommended) which will be used when translating non-local IPv4 addresses. This prefix must match the NAT64 prefix configured to the remote 464XLAT PLAT. SIIT EAM: Allows any IPv4 address to be converted to an IPv6 address by way of one simple configurable IPv6 prefix. Following fields need to be set: Default IPv6 Address pool: 32,40,48,56,64 or 96 bit IPv6 prefix (96 bit prefix recommended) which will be used when translating between IPv4 and IPv6 addresses. This prefix will be used when explicit mapping entries are not matching. SIIT EAM Mappings (Optional): Combination of IPv4 network prefix and IPv6 prefix definition. IPv4 prefix value must have identical or smaller number of suffix bits than its corresponding IPv6 prefix value.