how to configured two routers cisco 1841 ACL LIST with dynamic ip address
Here is a simple step-by-step configuration for two Cisco 1841 Integrated Services Router routers using:
Dynamic IP routing (RIP)
ACL (Access Control List)
Serial connection between routers
LAN connectivity
Network Diagram
PC1 ---- Router1 ===== Router2 ---- PC2
S0/0/0 S0/0/0
IP Address Plan
| Device | Interface | IP Address |
|---|---|---|
| Router1 | FastEthernet0/0 | 192.168.1.1 /24 |
| Router1 | Serial0/0/0 | 10.0.0.1 /30 |
| Router2 | Serial0/0/0 | 10.0.0.2 /30 |
| Router2 | FastEthernet0/0 | 192.168.2.1 /24 |
Step 1: Connect Routers
Use:
Console cable for configuration
Serial DCE/DTE cable between routers
Ethernet cable to PCs
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
Step 3: Configure Dynamic Routing (RIP)
router rip
version 2
network 192.168.1.0
network 10.0.0.0
no auto-summary
exit
Step 4: Configure ACL on Router1
Example:
Block PC network 192.168.1.0 from accessing Router2 LAN 192.168.2.0
access-list 100 deny ip 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255
access-list 100 permit ip any any
Apply ACL to serial interface:
interface serial0/0/0
ip access-group 100 out
exit
Step 5: 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
Step 6: Configure RIP on Router2
router rip
version 2
network 192.168.2.0
network 10.0.0.0
no auto-summary
exit
Step 7: Save Configuration
On both routers:
copy running-config startup-config
Step 8: Verify Configuration
Check Interfaces
show ip interface brief
Check Routing Table
show ip route
Check ACL
show access-lists
Test Connectivity
ping 10.0.0.2
ping 192.168.2.1
Important Notes
clock rate 64000is required only on DCE serial cable side.ACL 100 is an Extended ACL.
RIP dynamically shares routes between routers.
permit ip any anyallows remaining traffic.
Example ACL Types
Standard ACL
Blocks one source network only:
access-list 10 deny 192.168.1.0 0.0.0.255
access-list 10 permit any
Extended ACL
Blocks specific source and destination:
access-list 110 deny tcp 192.168.1.0 0.0.0.255 192.168.2.0 0.0.0.255 eq 80
access-list 110 permit ip any any
This blocks HTTP traffic only.
Useful Commands
| Command | Purpose |
|---|---|
show running-config | View configuration |
show ip route | View routes |
show access-lists | View ACL rules |
show controllers serial 0/0/0 | Check DCE/DTE |
ping | Test connectivity |