Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Maximum ACL rules


Is anybody aware of the maxinum number of access list rules an ASA can take.



Re: Maximum ACL rules

There is no maximum number of ACL entries which we can accommodate in ASA. It depends upon the DRAM size.

Syed Iftekhar Ahmed

New Member

Re: Maximum ACL rules

As your number of rules increases, the CPU load will increase as well. While there is no hard and fast limit I have had experience with a PIX 535 becoming CPU bound due to the size of the ACLs applied coupled with the complicated NAT rules and hundreds of static routes. In this case, the firewall would occasionally hit max CPU usage during peak traffic periods and start discarding packets.

Deleting ACL entries and cleaning up the config solved the issue in that situation.

Cisco Employee

Re: Maximum ACL rules


It is my understanding that the ASA uses around 20KB for an Access List Entry (ACE). So, the number of ACE really depends on the memory on the chassis and other features that are you planning to enable.

Below is the data sheet for the ASA that has information on various ASA platforms and memory.



** Please rate all helpful posts **

Re: Maximum ACL rules

adding to what has been said. I have found that many customers don't use object groups which can reduce the size of the ACLs substantially. The best approach is to create object groups, remove ACL with not hits, place the entries that are hited the most on the top of the ACL .. just my 20 cents ;-)

New Member

Maximum ACL rules

Hi, can you give me link for docs about ACLs processing?

It's interesting about object groups. Is there any processing docs and compare?

Maximum ACL rules

Hello Sergey,

I have read somewhere that each element or ACL entry requires about 40-56 bytes but there is no limit specific as there is in the FWSM where is normal to get warnings if you have a huge amount on ACLs.

I would not consider normal or common on an ASA to have a problem regarding CPU/Memory due to ACL's. I have not seen it before

Hope that I could help

Looking for some Networking Assistance? Contact me directly at I will fix your problem ASAP. Cheers, Julio Carvajal Segura
New Member

Maximum ACL rules

Hi, Julio!

I'm glad to see you.

Does ASA do some optinization of ACLs?

I mean, will be there any difference if ACL lines with heavy traffic will be at lines from 1 to 10 or they will be at lines from 500 to 509?

Maximum ACL rules


The optimization would be use object groups when possible so you can reduce the amount of ACL lines,

Remember to rate all of the helpful posts, that is as important as a thanks


Looking for some Networking Assistance? Contact me directly at I will fix your problem ASAP. Cheers, Julio Carvajal Segura