Most enterprise risk still passes through one place: the internet edge. Customer data leaves through it, partner APIs connect through it, and remote staff tunnel in through it every morning. More and more of that traffic is now generated by machines rather than people: AI agents calling APIs, chatbots pulling from internal knowledge bases, and attackers using automation to probe every exposed endpoint they can find.
That puts the edge firewall under pressure from two directions. It has to inspect more encrypted traffic than ever, without slowing the business down. When it falls behind, security teams end up choosing between looking closely at traffic and keeping things fast, which shouldn’t be a choice at all.
Cisco’s Secure Firewall 3100 Series is built for exactly that spot. Here’s how it handles the AI-era edge, with figures taken from Cisco’s published data sheet.
Why the edge got harder to defend
Encryption is the first problem. Most web and API traffic now runs over TLS, which hides payloads from any tool that only reads packet headers. Attackers know this and use encrypted channels for malware callbacks and data theft.
APIs are the second. Mobile apps, SaaS tools, partner systems, and now AI agents all exchange data through API endpoints. Attackers use automated scanners, increasingly AI-assisted ones, to find weak spots in them quickly. If your network is starting to carry agent traffic, it’s worth reading up on how AI agents affect network security before they multiply.
Remote access has also become permanent. VPN gateways now carry everyday workloads, so an outage there stops work immediately.
Machine learning that reads encrypted traffic without decrypting it
The most interesting AI feature on the 3100 sits in its Threat Defense software. Cisco’s Encrypted Visibility Engine (EVE) looks at the first packet of a TLS handshake, the Client Hello, and builds a fingerprint of the client that sent it. It combines that fingerprint with details like the destination address to work out which application or process is talking, without decrypting the session.
Machine learning does the heavy lifting behind the scenes. Cisco says it processes more than a billion TLS fingerprints and over 10,000 malware samples a day, and its fingerprint database maps more than 5,000 client processes to applications. Updates arrive through Cisco’s Vulnerability Database package.
When EVE meets a fingerprint it doesn’t recognise, it estimates a threat score from the destination details. Admins can set it to block at “Low” or “Very Low” thresholds. That’s handy for spotting malware hiding inside encryption, or an unapproved tool quietly sending company data to an outside AI service.
EVE doesn’t replace full TLS decryption where policy allows it. It does give visibility into traffic you can’t or won’t decrypt, such as banking or healthcare sessions you’re legally required to leave alone.
Protecting sensitive data and the APIs that expose it
Running as Threat Defense, the 3100 combines stateful firewalling, application visibility and Snort-based intrusion prevention in a single box. Policies can limit which users and applications reach systems holding regulated data, and IPS inspection blocks known exploits before they land.
API gateways and web servers belong in their own segmented zones rather than on a flat network. The firewall enforces those boundaries and applies intrusion signatures to the traffic heading toward them.
For request-level API validation, like checking schemas or catching broken authorization, you’ll still want a dedicated web application firewall or API security tool alongside it. Testing matters too. Teams adopting AI-driven attack path testing can find exposed API routes before attackers’ own automated tools do.
Keeping the edge itself standing
Every 3100 model is a 1RU appliance with two hot-swappable fan modules running in a redundant setup. Dual hot-swappable power supplies come standard on the 3130 and 3140 and are optional on the smaller models.
The 3110, 3120, 3130 and 3140 support clustering of up to eight units, so you can add capacity and redundancy without redesigning the edge. The entry-level 3105 doesn’t support clustering.
Every model can run either Cisco’s ASA software or Threat Defense, depending on how your team prefers to manage firewalls. Only Threat Defense includes the Snort IPS and EVE features covered above.
Sizing the right model
Cisco’s Threat Defense performance figures for the range look like this:
| Model | FW + AVC + IPS throughput | TLS throughput | Max VPN peers | Clustering |
| 3105 | 10 Gbps | 3.2 Gbps | 2,000 | Not supported |
| 3110 | 17 Gbps | 4.8 Gbps | 3,000 | Up to 8 units |
| 3120 | 21 Gbps | 6.7 Gbps | 7,000 | Up to 8 units |
| 3130 | 38 Gbps | 9.1 Gbps | 15,000 | Up to 8 units |
| 3140 | 45 Gbps | 11.5 Gbps | 20,000 | Up to 8 units |
Throughput figures are Cisco’s own, measured at 1024-byte packets. Real-world performance depends on your traffic mix and which features you switch on.
Most buyers skip the TLS column, but it’s often the one that should decide the model. As more traffic becomes encrypted, and more of it comes from AI tools and agents, the gap between headline throughput and TLS throughput is where an undersized firewall becomes a bottleneck.
For connectivity, the 3105 through 3120 offer 1G and 10G interfaces. The 3130 and 3140 add 25G ports, with network modules that include 40G options.
If you’re building a shortlist, you can compare interfaces and current pricing across the Cisco Secure Firewall 3100 Series range. It also helps to check warranty terms and whether the seller is a Cisco authorised partner, since that affects support contracts and software licensing.
Quick answers
Q. Can the 3100 run ASA software instead of Threat Defense?
Yes. Each model supports either one, though AI-assisted features like EVE need Threat Defense.
Q. Which model suits a midsize enterprise edge?
The 3110 or 3120 fits most midsize edges. The 3120 gives more headroom for VPN users and TLS inspection, roughly 6.7 Gbps against 4.8 Gbps.
Q. Does the series support 25G and 40G?
Only the 3130 and 3140. Both have 25G ports, and their network module options include 40G.
Q. Does EVE need decryption to work?
No. It fingerprints the TLS handshake, so it can flag suspicious clients and known malware even when sessions stay encrypted.
Final Words
A firewall that can’t keep up with encrypted traffic ends up waved through or switched to a lighter inspection mode, and attackers count on that. Size the box around TLS throughput and VPN peers rather than the headline number, segment your APIs, and leave room in the cluster for the agent traffic that’s coming.
Related: AI Hackers Are Getting Faster. Is Your Penetration Testing Keeping Up?
