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I have a problem with VPN configuration. This is the topology I created:

enter image description here

First updated licenses to make the VPN available:

license boot module c1900 technology-package securityk9

IPsec Router NetworkA configuration:

ip route 0.0.0.0 0.0.0.0 200.100.100.2 
!
access-list 100 permit ip 192.168.10.0 0.0.0.255 103.168.30.0 0.0.0.255
access-list 100 permit ip 192.168.10.0 0.0.0.255 103.168.40.0 0.0.0.255
access-list 100 permit ip 192.168.20.0 0.0.0.255 103.168.30.0 0.0.0.255
access-list 100 permit ip 192.168.20.0 0.0.0.255 103.168.40.0 0.0.0.255
!
crypto isakmp policy 10
encryption aes 256
authentication pre-share
group 5
!
crypto isakmp key VPN address 200.200.100.1
crypto ipsec transform-set VPN esp-aes 256 esp-sha-hmac
crypto map VPN 10 ipsec-isakmp 
set peer 200.200.100.1
set pfs group5
set security-association lifetime seconds 86400
set transform-set VPN
match address 100
!
interface gigabitEthernet 0/0
 crypto map VPN
!

Ipsec Router NetworkB:

ip route 0.0.0.0 0.0.0.0 200.200.100.2 
access-list 100 permit ip 192.168.30.0 0.0.0.255 103.168.10.0 0.0.0.255
access-list 100 permit ip 192.168.30.0 0.0.0.255 103.168.20.0 0.0.0.255
access-list 100 permit ip 192.168.40.0 0.0.0.255 103.168.10.0 0.0.0.255
access-list 100 permit ip 192.168.40.0 0.0.0.255 103.168.20.0 0.0.0.255
crypto isakmp policy 10
encryption aes 256
authentication pre-share
group 5
!
crypto isakmp key VPN address 200.100.100.1
crypto ipsec transform-set VPN esp-aes 256 esp-sha-hmac
crypto map VPN 10 ipsec-isakmp 
set peer 200.200.100.1
set pfs group5
set security-association lifetime seconds 86400
set transform-set VPN
match address 100
!
interface gigabitEthernet 0/0
 crypto map VPN
!

VLAN Router NetworkA

interface gigabitEthernet 0/1.1
 encapsulation dot1Q 10 
 ip address 192.168.10.1 255.255.255.0 
!
interface gigabitEthernet 0/1.2
 encapsulation dot1Q 20 
 ip address 192.168.20.1 255.255.255.0
!

VLAN Router NetworkB

interface gigabitEthernet 0/1.1
 encapsulation dot1Q 30 
 ip address 192.168.30.1 255.255.255.0 
!
interface gigabitEthernet 0/1.2
 encapsulation dot1Q 40 
 ip address 192.168.40.1 255.255.255.0
!

Switch1

interface gigabitEthernet 0/1
 switchport mode trunk
 switchport trunk allowed vlan 10,20
!
interface range fastEthernet 0/1-11
 switchport access vlan 10
!
interface range fastEthernet 0/11-20
 switchport access vlan 20
!

Switch2

interface gigabitEthernet 0/1
 switchport mode trunk
 switchport trunk allowed vlan 30,40
!
interface range fastEthernet 0/1-11
 switchport access vlan 30
!
interface range fastEthernet 0/11-20
 switchport access vlan 40
!

I would like VLANs to communicate with each other, however there is a problem with the VPN tunnel.

I think I need to configure NAT but don`t know how.

output "show crypto isakmp sa" is the same on both routers :

IPv4 Crypto ISAKMP SA
dst             src             state          conn-id slot status
!
IPv6 Crypto ISAKMP SA
!
11
  • Network topology prnt.sc/whchw3 – perelt Jan 6 at 8:30
  • Let's start with some basics. Please edit your question to include the output of "show crypto isakmp sa" on both routers. You shouldn't need NAT. – Ron Trunk Jan 6 at 13:44
  • I added the output. I don't think it looks like it should ;/ – perelt Jan 6 at 14:06
  • Can router A ping router B? – Ron Trunk Jan 6 at 14:07
  • Yes they can do it. – perelt Jan 6 at 14:12
1

You have a typo in your access-list that was not allowing traffic to enter the VPN tunnel:

access-list 100 permit ip 192.168.30.0 0.0.0.255 103.168.10.0 0.0.0.255
access-list 100 permit ip 192.168.30.0 0.0.0.255 103.168.20.0 0.0.0.255
access-list 100 permit ip 192.168.40.0 0.0.0.255 103.168.10.0 0.0.0.255
access-list 100 permit ip 192.168.40.0 0.0.0.255 103.168.20.0 0.0.0.255

Note 103.168.10.0 instead of 192.168.10.0

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