Question

An ISP is deploying DS-Lite to allow residential subscribers with IPv6-only access networks to reach the legacy IPv4 Internet. The subscriber CPE receives only an IPv6 prefix from the access network. During design review, an engineer must explain how a subscriber's IPv4 traffic actually traverses the network to reach IPv4 destinations. Which statement correctly describes the DS-Lite data plane behavior?

Accepted Answer

The B4 element in the CPE encapsulates the subscriber's private IPv4 packets in IPv6 and tunnels them to the AFTR, which decapsulates and performs NAT44 to a public IPv4 address.

Answer

The CPE performs stateful NAT64 locally, translating IPv4 packets into IPv6 before forwarding them natively across the access network to an IPv4 server.

Answer

The AFTR assigns a unique public IPv4 address to each subscriber's B4 element via DHCPv4-over-IPv6, eliminating the need for address translation.

Answer

The B4 element translates IPv4 into IPv6 using stateless MAP-T rules, and the border relay reverses the translation without maintaining per-flow state.