IPv4-initiated communication

As shown in Figure 110, when the IPv4 host initiates access to the IPv6 host, AFT operates as follows:

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

   • If a matching policy is found, AFT translates the destination IPv4 address according to the policy.

   • If no matching policy is found, AFT does not perform address translation.

2. AFT performs the pre-lookup to determine 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 IPv4 address with IPv4-to-IPv6 source address translation policies.

   • If a matching policy is found, AFT translates the source IPv4 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 IPv4 addresses and IPv6 addresses.

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

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

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