Related RFC's:

• Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion - https://tools.ietf.org/html/rfc6333
• Lightweight 4over6: An Extension to the Dual-Stack Lite Architecture - https://tools.ietf.org/html/rfc7596

VPP only supports lwAFTR.
In general, tests send IPv4 traffic in one side, observe correctly mapped IPv6 traffic on other side and vice versa.

Test suite contians following tests:

1. Encapsulate IPv4 into IPv6. IPv6 dst depends on IPv4 and UDP destination
2. Encapsulate IPv4 ICMP into IPv6. IPv6 dst depends on IPv4 addr and ICMP ID
3. Decapsulate IPv4 UDP from IPv6.
4. Hairpinning of traffic between two lwB4

VPP IP configuration:
if1: IPv4 - 10.0.0.1/24
if2: IPv6 - 2001::1/64

VPP map domain:
IPv6 preffix: 2001:1::/64
IPv4 preffix: 20.0.0.1/32
IPv6 src: 2001:1::1
PSID Length: 8
PSID Offset: 6

VPP map rule #1:
PSID: 52
IPv6 dst: 2001:1::2
Port from rule range:1232

VPP map rule #2:
PSID: 22
IPv6 dst: 2001:1::3
Port from rule range: 6232