how to configured two routers cisco 1841 vpn configuration with serial cable with commands
Cisco 1841 Site-to-Site VPN Configuration Using Serial Cable
This example shows how to configure two Cisco 1841 Integrated Services Router routers with:
Serial cable connection
Static IP addresses
Site-to-Site IPSec VPN
Basic routing
Network Diagram
LAN1 ---- Router1 ===== Serial Cable ===== Router2 ---- LAN2
PC1 PC2
192.168.1.0/24 192.168.2.0/24
IP Address Table
| Device | Interface | IP Address |
|---|---|---|
| Router1 | FastEthernet0/0 | 192.168.1.1 |
| Router1 | Serial0/0/0 | 10.0.0.1 |
| Router2 | FastEthernet0/0 | 192.168.2.1 |
| Router2 | Serial0/0/0 | 10.0.0.2 |
Step 1: Connect the Routers
Use:
Serial DCE cable
Connect Serial0/0/0 ↔ Serial0/0/0
One router must provide clock rate.
Step 2: Configure Router1
Enter Privileged Mode
enable
configure terminal
Configure Interfaces
interface fastethernet0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
exit
interface serial0/0/0
ip address 10.0.0.1 255.255.255.252
clock rate 64000
no shutdown
exit
Configure Static Route
ip route 192.168.2.0 255.255.255.0 10.0.0.2
Step 3: Configure Router2
enable
configure terminal
Configure Interfaces
interface fastethernet0/0
ip address 192.168.2.1 255.255.255.0
no shutdown
exit
interface serial0/0/0
ip address 10.0.0.2 255.255.255.252
no shutdown
exit
Configure Static Route
ip route 192.168.1.0 255.255.255.0 10.0.0.1
Step 4: Configure ISAKMP Policy (VPN Phase 1)
Router1
crypto isakmp policy 10
encryption aes
hash sha
authentication pre-share
group 2
lifetime 86400
exit
crypto isakmp key cisco123 address 10.0.0.2
Router2
crypto isakmp policy 10
encryption aes
hash sha
authentication pre-share
group 2
lifetime 86400
exit
crypto isakmp key cisco123 address 10.0.0.1
Step 5: Configure IPSec Phase 2
Router1
crypto ipsec transform-set VPN-SET esp-aes esp-sha-hmac
exit
access-list 100 permit ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255
crypto map VPN-MAP 10 ipsec-isakmp
set peer 10.0.0.2
set transform-set VPN-SET
match address 100
exit
interface serial0/0/0
crypto map VPN-MAP
exit
Router2
crypto ipsec transform-set VPN-SET esp-aes esp-sha-hmac
exit
access-list 100 permit ip 192.168.2.0 0.0.0.255 192.168.1.0 0.0.0.255
crypto map VPN-MAP 10 ipsec-isakmp
set peer 10.0.0.1
set transform-set VPN-SET
match address 100
exit
interface serial0/0/0
crypto map VPN-MAP
exit
Step 6: Save Configuration
Both Routers
end
write memory
OR
copy running-config startup-config
Step 7: Verify VPN
Check Interfaces
show ip interface brief
Check VPN Status
show crypto isakmp sa
show crypto ipsec sa
Step 8: Test Connectivity
From Router1:
ping 192.168.2.1
From Router2:
ping 192.168.1.1
Expected Result
Serial interfaces should be UP
VPN tunnel should establish automatically
PCs from both LANs can communicate securely
Useful Troubleshooting Commands
show running-config
show controllers serial 0/0/0
debug crypto isakmp
debug crypto ipsec
Simple VPN Process
Configure interfaces
Configure routing
Configure ISAKMP policy
Configure pre-shared key
Configure IPSec transform set
Create ACL
Apply crypto map
Test VPN