In Large Scale NAT, NAT is performed twice. The first layer of NAT is at home gateway and the second layer of NAT is at CGN. There are three types of IPv4 address blocks in LSN. IPv4 users inside home gateway will get private address [11] from their home router. This private IPv4 address is translated at home gateway to the IPv4 address in the block 100.64.0.0/10 assigned by IANA for CGN use. This address gets translated to public IPv4 address at the CGN