464XLAT according to RFC 6877 is a procedure that translates from IPv4 to IPv6 and back to IPv4. The method is often used by mobile network providers to enable IPv4 access in an IPv6-only APN based on NAT64. Two sides are involved in 464XLAT: The client side or client translator (CLAT - customer-side translator) and the provider translator (PLAT - provider-side translator) or NAT64 gateway of the provider. The LCOS supports the CLAT side to enable a network behind a router to access IPv4 networks. In contrast to DS-Lite, which establishes a 4in6 tunnel to the AFTR gateway, 464XLAT uses a translation of the IPv4 packet to IPv6. On the PLAT side, the packet is translated back into IPv4. The name 464 results from the two-way translation. Generally, the NAT64 prefix 64:ff9b::/96 is used for the translation on the provider side. To use 464XLAT, it is first necessary to configure an IPv6 connection. A 464XLAT peer is then added. The IPv4 default route then points to this peer.
The configuration takes place in LANconfig under .
- Peer
- Set a unique name for this peer. Max. 16 characters as capital letters.
- Destination interface
- Name of the underlying WAN interface or the underlying peer, e.g. INTERNET. Max. 16 characters as capital letters.
- CLAT mode
- Defines with which method the CLAT prefix should be generated.
- DHCPv6-PD
- If the Internet provider uses DHCPv6 prefix delegation, e.g. for DSL or cable connections, the CLAT mode DHCPv6-PD must be used. The subnet ID can be used to control which subnet of the delegated prefix should be used for the CLAT prefix. The subnet ID can be configured as 0, 1 or FF, for example.
- WWAN (Default)
- If the Internet connection is a cellular connection (WWAN), the CLAT mode WWAN must be used. The CLAT prefix is formed from the /64 WAN prefix. The subnet ID must be 0 or empty. NAT must be enabled in the IPv4 routing table for the WAN connection.
- Static
- If the Internet provider uses a static prefix, the static /64 prefix for the CLAT prefix can be used in the Subnet ID field, e.g. 2001:db8:: (without the /64 specification). This mode can also be used if 464XLAT is to be used on a VPN connection or tunnel interface. In this case, the VPN interface must have a static IPv6 address configured.
- Subnet ID
- Subnet ID that is combined with the provider's delegated DHCPv6 prefix. The IPv4 source address is embedded in the resulting prefix when the packet is sent over the WAN. In the case of a WWAN connection (/64 prefix), the parameter can be configured either with the value 0 or left empty (default). If the value static is used for CLAT mode, the static /64 prefix can be configured as the CLAT prefix in the Subnet ID field, e.g. 2001:db8:: (without the /64 specification). Example for subnet IDs: 0, 1, 12, 1f3b or 2001:db8::
- PLAT prefix
- IPv6 prefix used on the provider side for translation. If the value is left empty, a DNS prefix discovery according to RFC 7050 is performed to automatically determine the PLAT prefix. Default: 64:ff9b::/96
