IPv6 ALG Support for ICMP (Routing, NAT, NAT-PT support)

The Internet Control Message Protocol (ICMP) Application Layer Gateway (ALG) is one of the ALG?s that handle ICMP traffic.

IPv6 nodes use the ICMPv6 protocol to report errors encountered in processing packets and to perform other Internet-layer functions such as diagnostics. ICMPv6 is an integral part of IPv6 and must be fully implemented by every IPv6 node; therefore the ALG layer is always enabled for ICMPv6.