Hi jsarkis520,
Can you elaborate more on NAT session? Generally when connection starts from source to destination, then firewall starts to maintain the connection session. In connection session you can view the NAT information. FTD2130 Concurrent session is 2Million with AVC. Below the URL you can find the concurrent session and throughput information for. kindly let us know if you have more queries
https://www.cisco.com/c/en/us/products/collateral/security/firepower-2100-series/datasheet-c78-742473.html
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You can also learn more about Secure Firewall (formerly known as NGFW) through our live Ask the Experts (ATXs) session. Check out Cisco Network Security ATXs Resources [https://community.cisco.com/t5/security-knowledge-base/cisco-network-security-ask-the-experts-resources/ta-p/4416493] to view the latest schedule for upcoming sessions, as well as the useful references, e.g. online guides, FAQs.
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Regards
Arunkumar