isp#show run
interface Loopback0
 ip address 10.200.2.1 255.255.255.0
!        
interface Serial1/0
 ip address 10.200.1.1 255.255.255.0
 no sh
!
!
ip route 172.16.0.0 255.255.0.0 10.200.1.2
!

#################################

r1#show run

interface FastEthernet0/0.1
 no sh
 description management vlan 1
 encapsulation dot1Q 1 native
 ip address 172.16.1.1 255.255.255.0
!
interface FastEthernet0/0.10
 description accounting vlan 10
 encapsulation dot1Q 10
 ip address 172.16.10.1 255.255.255.0
 no sh
!
interface FastEthernet0/0.20
 description marketing vlan 20
 encapsulation dot1Q 20
 ip address 172.16.20.1 255.255.255.0
 no sh
!
interface Serial1/0
 ip address 10.200.1.2 255.255.255.0
 no sh
!
ip route 0.0.0.0 0.0.0.0 10.200.1.1
!
!
$$$$$$$$$$$$$$$$$$$$$

sw1#show run

interface FastEthernet1/11
 switchport access vlan 10
 spanning-tree portfast
!
interface FastEthernet1/12
 switchport access vlan 20
 spanning-tree portfast
!
interface FastEthernet1/15
 switchport mode trunk
!
interface Vlan1
 ip address 172.16.1.2 255.255.255.0
!
ip http server
ip route 0.0.0.0 0.0.0.0 172.16.1.1
!

sw1#
####################

 

pc1#show run

interface FastEthernet0/0
 ip address 172.16.10.2 255.255.255.0
 speed auto
 full-duplex
 no sh
!        
ip classless
ip route 0.0.0.0 0.0.0.0 172.16.10.1
################

pc2#show run
!
interface FastEthernet0/0
 ip address 172.16.20.2 255.255.255.0
 speed auto
 full-duplex
 no sh
!        
ip classless
ip route 0.0.0.0 0.0.0.0 172.16.20.1
ip http server

pc2#ping 172.16.10.2