how to configured two routers standard ACL LIST with serial cable command prompt 2026
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How to Configure Two Routers Using Standard ACL with Serial Cable (Command Prompt) – Complete Guide 2026 (Part 6)
Author: Sreekrishna Tech Solutions
Email: pgollabala@gmail.com
Website: https://sreekrishnatechsolutionsatp2026.blogspot.com/
Introduction
Configuring routers using Access Control Lists (ACLs) is a fundamental skill for networking professionals and students preparing for certifications. In this guide, we will walk through how to configure two routers connected via a serial cable using Standard ACLs through the command line interface (CLI).
This tutorial is designed to help beginners and intermediate learners understand real-world networking scenarios. It is also optimized for SEO ranking, ensuring better visibility and helping your blog get Google AdSense approval.
What is a Standard ACL?
A Standard Access Control List (ACL) is used to filter traffic based on the source IP address only. It is simpler compared to extended ACLs and is typically placed close to the destination network.
Key Features:
Filters only source IP
Uses numbers 1–99
Easy to configure
Less granular control than extended ACLs
Network Topology
We will configure two routers connected via a serial cable:
PC1 ---- Router1 ===== Router2 ---- PC2
Router1 Serial Interface → Router2 Serial Interface
Each router has a LAN network
ACL will be applied to restrict traffic
IP Addressing Table
| Device | Interface | IP Address | Subnet Mask |
|---|---|---|---|
| Router1 | Fa0/0 | 192.168.1.1 | 255.255.255.0 |
| Router1 | S0/0/0 | 10.0.0.1 | 255.255.255.252 |
| Router2 | S0/0/0 | 10.0.0.2 | 255.255.255.252 |
| Router2 | Fa0/0 | 192.168.2.1 | 255.255.255.0 |
Step 1: Configure Router1
Open CLI and enter the following commands:
enable
configure terminal
interface fastethernet0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
interface serial0/0/0
ip address 10.0.0.1 255.255.255.252
clock rate 64000
no shutdown
exit
Step 2: Configure Router2
enable
configure terminal
interface fastethernet0/0
ip address 192.168.2.1 255.255.255.0
no shutdown
interface serial0/0/0
ip address 10.0.0.2 255.255.255.252
no shutdown
exit
Step 3: Configure Routing
To allow communication between networks, configure static routing.
On Router1:
ip route 192.168.2.0 255.255.255.0 10.0.0.2
On Router2:
ip route 192.168.1.0 255.255.255.0 10.0.0.1
Step 4: Configure Standard ACL
Let’s block traffic from network 192.168.1.0 to Router2 LAN.
On Router2:
access-list 10 deny 192.168.1.0 0.0.0.255
access-list 10 permit any
interface fastethernet0/0
ip access-group 10 out
Explanation
access-list 10 deny 192.168.1.0 0.0.0.255→ Blocks source networkaccess-list 10 permit any→ Allows all other trafficip access-group 10 out→ Applies ACL on outgoing interface
Step 5: Verify Configuration
Use the following commands:
show access-lists
show ip interface
show running-config
Test connectivity using:
ping 192.168.2.1
If ACL is working, ping should fail from blocked network.
Important Tips
Always place Standard ACL near destination
Use wildcard masks carefully
Order of rules matters (top-down execution)
Always include
permit anyat the end
Common Errors and Troubleshooting
1. Interface Down
Use:
no shutdown
2. Incorrect IP Address
Verify using:
show ip interface brief
3. ACL Not Applied
Check:
show running-config
Real-World Use Case
Standard ACLs are useful in:
Blocking specific departments
Restricting unauthorized access
Basic network security implementation
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Conclusion
In this tutorial, you learned how to configure two routers using a serial cable and apply a Standard ACL using command-line interface. This is a crucial skill for networking exams and real-world scenarios.
By following this guide, you not only improve your technical knowledge but also create SEO-optimized content that can rank on Google and help achieve AdSense approval.
Next Part (Part 7)
In the next tutorial, we will cover:
👉 Extended ACL Configuration
👉 Real-time Packet Filtering
👉 Advanced Security Rules
Stay tuned!
Published by: Sreekrishna Tech Solutions
Contact: pgollabala@gmail.com
Blog: https://sreekrishnatechsolutionsatp2026.blogspot.com/