Question about ASA CPU usage

[jhseol@ugent.co.kr]

Hi My client is planing to extent their company size.

They are using ASA5516 for firewall. And the CPU usage is 15%~20%.

what I want to know is a limit CPU usage for stable operating of ASA5516.

Thank you.

[Shubham Bharti · Accepted solution]

If it is just a firewall, a prolonged 80% usage is where I would start looking for a hardware upgrade. 

If there is a sfr involved, I would suggest 60% for a safe bet.

[jhseol@ugent.co.kr]

it's just seperate vlans and dhcp server on it. probably 150 users are using now. and users will be increase up to 200~250

[Shubham Bharti]

There are other criterias that also dictates whether its time to upgrade hardware or not such as:

• Maximum Throughput
• Maximum Concurrent Connections

For maximum throughput: Any network monitoring tool in the organization should be able to help you with this. 1.8 Gbps is the limit according to the datasheet. 

For maximum concurrent connection: With 250 users, we assume x connections per user. Total concurrent connection will be 250x. The network team will be much accurate with the value of x as they are familiar with the environment. 250,000 is the limit for ASA-5516-X according to the datasheet.  

Well, all of them do end up affecting CPU usage. So, 80% of any of the parameters is where I would suggest you to look for a hardware upgrade.