Configure Site-to-Site VPN with Cisco IOS 
   Configure IPsec VPN Settings on R1 and R3
    Verify connectivity from the R1 LAN to the R3 LAN
   
     Enable IKE policies on R1 and R3
      R1(config)# crypto isakmp enable
      R3(config)# crypto isakmp enable 
      R1(config)# crypto isakmp policy 10
   
    Configure the IKE Phase 1 ISAKMP policy on R1 and R3
     R1(config)# crypto isakmp policy 10 
     R1(config-isakmp)# hash sha 
     R1(config-isakmp)# authentication pre-share 
     R1(config-isakmp)# group 14 
     R1(config-isakmp)# lifetime 3600 
     R1(config-isakmp)# encryption aes 256 
     R1(config-isakmp)# end
     R3(config)# crypto isakmp policy 10 
     R3(config-isakmp)# hash sha 
     R3(config-isakmp)# authentication pre-share 
     R3(config-isakmp)# group 14 
     R3(config-isakmp)# lifetime 3600 
     R3(config-isakmp)# encryption aes 256 
     R3(config-isakmp)# end  
    
  
  Configure pre-shared keys. 
   R1(config)# crypto isakmp key cisco123 address 10.2.2.1 
   R3(config)# crypto isakmp key cisco123 address 10.1.1.1
  
  Configure the IPsec transform set and lifetime. 
   R1(config)# crypto ipsec transform-set 50 esp-aes 256 esp-sha-hmac 
   R3(config)# crypto ipsec transform-set 50 esp-aes 256 esp-sha-hmac
   R1(config)# crypto ipsec security-association lifetime seconds 1800 
   R3(config)# crypto ipsec security-association lifetime seconds 1800 
   
  Define interesting traffic
   R1(config)# access-list 101 permit ip 192.168.1.0 0.0.0.255 192.168.3.0 0.0.0.255 
   R3(config)# access-list 101 permit ip 192.168.3.0 0.0.0.255 192.168.1.0 0.0.0.255
   
   
  Create and apply a crypto map. 
    R1(config)# crypto map CMAP 10 ipsec-isakmp
    R1(config-crypto-map)# match address 101
    R1(config-crypto-map)# set peer 10.2.2.1 
    R1(config-crypto-map)# set pfs group14 
    R1(config-crypto-map)# set transform-set 50 
    R1(config-crypto-map)# set security-association lifetime seconds 900 
    
    R3(config)# crypto map CMAP 10 ipsec-isakmp 
    R3(config-crypto-map)# match address 101 
    R3(config-crypto-map)# set peer 10.1.1.1 
    R3(config-crypto-map)# set pfs group14 
    R3(config-crypto-map)# set transform-set 50 
    R3(config-crypto-map)# set security-association lifetime seconds 900
    
    R1(config)# interface S0/0/0 
    R1(config-if)# crypto map CMAP 
    
    R3(config)# interface S0/0/1 
    R3(config-if)# crypto map CMAP
    
    
  Verify
   R1# show crypto isakmp policy
   R1# show crypto ipsec transform-set 
   R1# show crypto map 
   R1# show crypto isakmp sa 
   R1# show crypto ipsec sa