IPv6-initiated communication

As shown in Figure 109, when the IPv6 host initiates access to the IPv4 host, AFT operates as follows:

1. Upon receiving a packet from the IPv6 host, AFT compares the packet with IPv6-to-IPv4 destination address translation policies.

   • If a matching policy is found, AFT translates the destination IPv6 address according to the policy.

   • If no matching policy is found, AFT does not process the packet.

2. AFT performs pre-lookup to determine the output interface for the translated packet. PBR is not used for the pre-lookup.

   • If a matching route is found, the process goes to step 3.

   • If no matching route is found, AFT discards the packet.

3. AFT compares the source IPv6 address of the packet with IPv6-to-IPv4 source address translation policies.

   • If a matching policy is found, AFT translates the source IPv6 address according to the policy.

   • If no matching policy is found, AFT discards the packet.

4. AFT forwards the translated packet and records the mappings between IPv6 addresses and IPv4 addresses.

5. AFT translates the IPv4 addresses in the response packet header to IPv6 addresses based on the address mappings before packet forwarding.

For more information about IPv6-to-IPv4 destination address translation policies, see "Configuring an IPv6-to-IPv4 destination address translation policy."

For more information about IPv6-to-IPv4 source address translation policies, see "Configuring an IPv6-to-IPv4 source address translation policy."