nat64 toa enable

By default, the NAT64 TCP option address function is disabled.

After the NAT64 TCP option address function is enabled, the device fills the pre-NAT64 information (including the source address and port) in the TCP option field of the ACK packet and sends the ACK packet to the peer server during the three-way handshake for establishing a TCP connection. In public cloud scenarios, when an IPv6 user accesses an IPv4 server, the source address of the packet is translated into an IPv4 address after NAT64, but the peer server wants to obtain the actual IPv6 source address of the user. In this case, the NAT64 TCP option address function must be enabled. The source address and source port of the IPv6 user are sent to the peer server through the TCP option field.

In hot standby networking, you need to configure the function on both the active and standby devices. Otherwise, the NAT64 TCP option address function does not take effect on the standby device.