ACLs: Named vs Numbered – Which One Should You Use? [CCNP ENTERPRISE]

Access Control Lists (ACLs) are among the first tools you reach for when you want to secure or control traffic. But when it comes to Named vs Numbered ACLs, many learners (and even working professionals) hesitate — unsure which one to use, when, and why.

Let me take you back to my first real-world ACL troubleshooting scenario — a production router, a messy numbered ACL with no comments, and a lot of guesswork. That was the moment I realized: choosing the right type of ACL matters not just for function, but for manageability too.

In this article, we’ll decode the differences, explore real-world usage, and do a hands-on lab in EVE-NG. Let’s go!

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Theory in Brief: What are ACLs?

Access Control Lists (ACLs) are used in networking to control the flow of packets. Think of them as filters placed on interfaces that allow or deny traffic based on IP addresses, protocols, ports, or other parameters.

ACLs come in two primary types:

• Numbered ACLs: Identified by a numeric value (like 1–99, 100–199, etc.)
• Named ACLs: Identified by a string name you define (like “BLOCK-WEB” or “PERMIT-ADMIN”)

Both do the same job — but with different flexibility and management ease.

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Why Compare Named vs Numbered?

Numbered ACLs are quick and simple but rigid.
Named ACLs are more readable, editable, and scalable — especially useful in enterprise networks.

The key use cases include:

• Controlling access between subnets or VLANs
• Permitting or denying specific applications or services (like HTTP, SSH)
• Filtering routing updates (BGP, OSPF, EIGRP)

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Comparison: Named vs Numbered ACLs

Feature	Numbered ACLs	Named ACLs
Identifier	Number (1–199, 1300–2699, etc.)	User-defined string name
Editing	Cannot insert/delete mid-sequence	Supports adding/removing lines
IPv6 Support	Not supported	Fully supported
Clarity	Harder to understand/debug	Easier to read/maintain
Use Case	Small configs, quick tests	Production, enterprise environments
Support for remarks	No	Yes
Protocol flexibility	Standard/Extended limited by range	Full protocol support

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CLI Commands (Cisco IOS)

Purpose	Command Example
Create Numbered Standard ACL	access-list 10 permit 192.168.1.0 0.0.0.255
Create Numbered Extended ACL	access-list 101 permit tcp any any eq 80
Create Named Standard ACL	ip access-list standard BLOCK-LAN permit 10.0.0.0 0.0.0.255
Create Named Extended ACL	ip access-list extended WEB-FILTER deny tcp any any eq 80
Add remark to Named ACL	remark Block all HTTP traffic
Apply ACL to interface (inbound)	ip access-group 101 in or ip access-group WEB-FILTER in
Show ACLs	show access-lists or show ip access-lists
Remove ACL from interface	no ip access-group 101 in
Remove a line in Named ACL	no 10 (inside ACL config mode)

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Real-World Use Cases

Scenario	ACL Type	Description
Block HTTP traffic in Guest VLAN	Named Extended	Easy to read and edit later
Allow only specific subnet into DMZ	Numbered Standard	Quick config on a test device
Filter BGP updates to peers	Named Extended	Use sequence numbers and remarks
IPv6 ACL for data center servers	Named IPv6 ACL	Named ACLs are required for IPv6
Permit SSH access to management IPs only	Named Extended	Precise, clean, and auditable

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EVE-NG Lab – ACLs in Action

Topology:

Goal:

• Block HTTP traffic from PC1 to Server1 using both Numbered and Named ACLs on Router R1.

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Configuration Steps:

R1 – Using Numbered ACL

interface Gig0/0
 description Link to PC1
 ip address 192.168.1.1 255.255.255.0

interface Gig0/1
 description Link to R2
 ip address 10.1.1.1 255.255.255.0

access-list 100 deny tcp any any eq 80
access-list 100 permit ip any any

interface Gig0/0
 ip access-group 100 in

R1 – Using Named ACL (Alternative)

ip access-list extended BLOCK-WEB
 deny tcp any any eq 80
 permit ip any any

interface Gig0/0
 ip access-group BLOCK-WEB in

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Troubleshooting Tips

Symptom	Cause	Troubleshooting Command
ACL not taking effect	Not applied to interface	`show run
All traffic blocked	Missing final permit ip any any	Always end with a permit rule
Can’t edit existing Numbered ACL	Numbered ACLs are not editable	Recreate the ACL or switch to named ACLs
Named ACL sequence not working	Wrong sequence number used	show ip access-lists, check & edit as needed
ACL blocking unintended traffic	Rule order mismatch	Reorder or add remarks to improve clarity

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FAQ – ACLs: Named vs Numbered

1. What is the difference between standard and extended ACLs?

Answer:
Standard ACLs filter traffic based only on the source IP address, while extended ACLs allow filtering based on source IP, destination IP, protocol, and port numbers.
Use standard ACLs for basic filtering and extended ACLs for precise traffic control.

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2. What are the key differences between named and numbered ACLs?

Answer:
The major differences are:

• Identification: Numbered ACLs use predefined numbers (e.g., 1–199), while named ACLs use custom names.
• Editability: Named ACLs allow inserting/removing entries with sequence numbers.
• Readability: Named ACLs are easier to understand and document with remark.
• IPv6: Only named ACLs support IPv6.

Named ACLs are better suited for enterprise environments.

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3. When should I use a numbered ACL instead of a named one?

Answer:
Numbered ACLs are suitable for:

• Quick testing in lab environments
• Small-scale deployments where minimal filtering is needed
• Legacy IOS devices where named ACLs may not be supported

For anything more complex, named ACLs are preferred.

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4. Can I modify a specific entry in a numbered ACL?

Answer:
No, numbered ACLs must be completely deleted and recreated to modify individual lines.
Only named ACLs allow editing specific entries using sequence numbers.

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5. How do I add or remove rules in a named ACL?

Answer:
Use sequence numbers inside the ACL config mode:

ip access-list extended BLOCK-TELNET
 10 deny tcp any any eq 23
 20 permit ip any any

To remove a line:

no 10

To insert a new rule:

15 deny tcp 192.168.1.0 0.0.0.255 any eq 80

This flexibility is why named ACLs are preferred in production.

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6. Are ACLs stateful or stateless?

Answer:
ACLs on Cisco routers are stateless, meaning they inspect only the packet in one direction.
They do not automatically allow return traffic. For stateful inspection, you need zone-based firewalls or CBAC.

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7. What happens if no ACL line matches a packet?

Answer:
There is an implicit deny all at the end of every ACL.

If no rule matches, the traffic is blocked by default. Always include a final permit if you want to allow unmatched traffic, like:

permit ip any any

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8. Can I use remarks to document ACLs?

Answer:
Yes, but only in named ACLs.
Use remark to document each rule’s purpose for better readability:

ip access-list extended BLOCK-WEB
 remark Deny HTTP from Guest VLAN
 deny tcp 192.168.20.0 0.0.0.255 any eq 80
 permit ip any any

Remarks are not supported in numbered ACLs.

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9. How do I apply ACLs to interfaces?

Answer:
Use the ip access-group command:

interface Gig0/1
 ip access-group BLOCK-WEB in

Direction options:

• in: Filters packets entering the interface
• out: Filters packets leaving the interface

Always test direction carefully to avoid service disruptions.

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10. Do ACLs impact router performance?

Answer:
Minimal, especially on modern hardware. However:

• Large ACLs (hundreds of entries) may increase CPU usage
• Complex ACLs with wildcard matching require more processing
• Always avoid unnecessary ACLs on high-throughput interfaces

Use show processes cpu and show access-lists to monitor impact.

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YouTube Link

Watch the Complete CCNP Enterprise: ACLs: Named vs Numbered – Which One Should You Use? Lab Demo & Explanation on our channel:

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Final Note

Understanding how to differentiate and implement ACLs: Named vs Numbered – Which One Should You Use? is critical for anyone pursuing CCNP Enterprise (ENCOR) certification or working in enterprise network roles. Use this guide in your practice labs, real-world projects, and interviews to show a solid grasp of architectural planning and CLI-level configuration skills.

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