ISP1#show run
!
interface Loopback0
 ip address 10.0.1.2 255.255.255.252
!
interface Serial1/1
 ip address 10.0.0.5 255.255.255.252
 no sh
!
ip classless
ip route 42.0.0.48 255.255.255.240 10.0.0.6

SAN1#show run
!
interface FastEthernet0/0
 ip address 192.168.0.1 255.255.255.0
 ip nat inside 
 no sh
!
interface Serial1/0
 ip address 10.0.0.6 255.255.255.252
 ip nat outside
 no sh
!!
ip nat inside source static 192.168.0.3 42.0.0.49
ip nat inside source static 192.168.0.4 42.0.0.50
ip nat inside source static 192.168.0.5 42.0.0.51
ip classless
ip route 0.0.0.0 0.0.0.0 10.0.0.5

PC1#show run
!
interface FastEthernet0/0
 ip address 192.168.0.20 255.255.255.0
!
ip default-gateway 192.168.0.1
!no ip routing

PC2#show run
!!
interface FastEthernet0/0
 ip address 192.168.0.5 255.255.255.0
!
ip default-gateway 192.168.0.1
no ip routing
!