In today’s network-driven world, protecting data in motion is more important than ever. While we often focus on securing applications or encrypting traffic at higher layers, there’s one layer that’s just as critical — the link layer. That’s where MACsec (Media Access Control Security, IEEE 802.1AE) comes in.

MACsec is a powerful Layer 2 security protocol built to secure Ethernet links — whether you’re connecting servers inside a data center, switches across a campus, or hosts within a LAN. And with Asterfusion’s CX202P-24Y-M-H switch, powered by the high-performance Marvell Aldrin3 chip, you get native MACsec support out of the box. That means hardware-accelerated encryption, authentication, and integrity protection — all without compromising speed or performance.

Let’s dive into how MACsec works, why it matters, and how it compares to other security protocols like IPsec and TLS.

What is MACsec?

MACsec (Media Access Control Security, IEEE 802.1AE) is a link-layer security protocol designed to secure Ethernet link communications. Operating at Layer 2 (Data Link Layer) of the OSI model, it protects Ethernet frames, ensuring data is not intercepted, tampered with, or forged on physical or virtual links.

Key Features:

• Data Encryption: Encrypts the payload of Ethernet frames to prevent interception and decoding.
• Data Integrity: Uses an Integrity Check Value (ICV) to verify that data has not been altered.
• Data Origin Authentication: Ensures data originates from a trusted sender.
• Replay Protection: Prevents attackers from replaying captured frames.

Why Do We Need MACsec?

It fills a crucial security gap. Most modern security protocols focus on traffic between endpoints (like apps or tunnels), but Ethernet itself remains exposed ：

• Link-Layer Security: Traditional security protocols like IPsec or TLS operate at Layer 3 (Network Layer) or higher, leaving Layer 2 Ethernet frames unprotected. MACsec fills this gap, securing Ethernet links.
• Internal LAN Threats: In data centers, enterprise LANs, or cloud environments, internal networks may face risks of eavesdropping, data tampering, or forgery. MACsec provides hop-by-hop protection for switch-to-switch or host-to-switch communications.
• High-Performance Needs: MACsec is designed for efficiency, making it suitable for high-bandwidth, low-latency scenarios like data center internal communications.

How Does It Work?

MACsec is largely a hardware-oriented function, with its efficiency and low-latency characteristics relying on dedicated encryption hardware in IEEE 802.1AE-compliant network devices. Its workflow is as follows:

Key Negotiation:

• Uses the MACsec Key Agreement (MKA) protocol (based on IEEE 802.1X) to negotiate and distribute encryption keys between communicating parties.
• MKA ensures only authorized devices participate in secure communication, typically implemented with hardware and firmware for efficient key management.

Frame Encryption and Authentication:

• The sender encrypts the Ethernet frame’s payload and adds a SecTAG (containing security parameters like key identifiers) and ICV.
• The SecTAG identifies the key and encryption policy, while the ICV verifies data integrity.
• Encryption and integrity checks are typically performed by hardware acceleration modules (e.g., ASICs or FPGAs) to ensure high throughput and low latency.

Transmission and Decryption:

• Encrypted frames are transmitted over the Ethernet link.
• The receiver uses the shared key to decrypt the frame and verify the ICV and frame integrity, also relying on hardware acceleration.

Replay Protection:

• MACsec uses a sequence number (Packet Number, PN) to prevent replay attacks, ensuring frames are received in order.

The encryption algorithm typically uses AES-GCM (Galois/Counter Mode), providing efficient encryption and integrity protection through hardware implementation.

Hardware-Oriented Characteristics

MACsec’s core functionality heavily relies on hardware support for the following reasons:

• Encryption Performance: AES-GCM encryption and decryption require high computational performance. Software implementations introduce latency and performance bottlenecks, while MACsec-enabled NICs and switches have built-in encryption engines for real-time processing.
• Frame Processing Efficiency: MACsec processes Ethernet frames packet-by-packet at the link layer, requiring minimal processing overhead that only dedicated hardware can achieve for high-bandwidth demands.
• Deployment Requirements: Requires IEEE 802.1AE-compliant network devices (e.g., switches, routers, or NICs). For example, devices like the CX202P-24Y-M-H have built-in acceleration (thanks to the Marvell Aldrin3) to handle these tasks without impacting throughput — a critical feature in data centers, financial networks, or anywhere performance is king.

While software plays a supporting role in configuration (e.g., via network management tools) and key management, in production environments, MACsec’s encryption, decryption, and frame processing are almost entirely hardware-based. If network devices lack MACsec support, hardware upgrades may be necessary.

Comparison with MACsec, IPsec, TLS

MACsec, IPsec, and TLS differ significantly in protocol layer, use cases, and functionality. Below is a detailed comparison:

Feature	MACsec	IPsec	TLS
Protocol Layer	Data Link Layer (Layer 2)	Network Layer (Layer 3)	Transport/Application Layer (Layer 4/5)
Protection Scope	Ethernet frames (hop-by-hop)	IP packets (end-to-end or gateway-to-gateway)	Application data (end-to-end)
Encrypted Object	Ethernet frame payload	IP packet payload	Application data (e.g., HTTP, FTP)
Use Cases	LANs, data centers, switch-to-switch	VPNs, remote access, site-to-site	Web browsing, email, app communication
Performance	High performance, low latency (hardware-accelerated)	Moderate (software or hardware, more complex than MACsec)	Higher overhead (software-based, complex handshake)
Key Management	MKA (based on 802.1X)	IKE (Internet Key Exchange)	TLS handshake protocol
Deployment Complexity	Hardware-dependent, relatively simple	Complex, requires tunnel or transport mode setup	App-dependent, flexible but requires certificate management
End-to-End vs. Hop-by-Hop	Hop-by-hop protection	End-to-end or gateway-to-gateway	End-to-end
Typical Algorithms	AES-GCM	AES-CBC, AES-GCM	AES, ChaCha20

Real-World Use Cases for MACsec

MACsec shines in any scenario where link-level security is essential — especially where performance and latency matter:

• Data Centers: Protect east-west traffic between servers and switches.
• Enterprise LANs: Secure internal communications, especially in open-floor offices or multi-tenant buildings.
• Cloud Networks: Extend Layer 2 security into VXLAN and virtual environments.
• Industrial IoT: Shield control traffic in real-time automation and monitoring systems.
• High-Frequency Trading: Preserve ultra-low latency while keeping sensitive data secure.

A Few Things to Keep in Mind

• Built for Hardware: MACsec isn’t something you just flip on in software and expect blazing performance. It’s designed to run on IEEE 802.1AE-compliant hardware — like switches, routers, or NICs with built-in encryption engines. While software-based MACsec exists, it’s mainly for testing or lab use, not production environments.

• VLAN-Friendly: No worries if you’re running VLANs. MACsec fits right in — the security tag (SecTAG) is simply inserted after the VLAN tag in the Ethernet frame, keeping things neat and standards-compliant.

• Point-to-Point Only: One important caveat — MACsec secures direct links only. It doesn’t provide end-to-end encryption across an entire network path, and it leaves Ethernet headers (like MAC addresses) unencrypted. That means it’s perfect for protecting link-level traffic, but not a full replacement for higher-layer security protocols like IPsec or TLS.

Secure Your Links with Asterfusion CX202P-24Y-M-H

Looking for a switch that takes MACsec seriously? The Asterfusion CX202P-24Y-M-H is built for it.

This compact yet powerful 24-port SFP28 25G Switch, 2 x 100G QSFP28/40G QSFP+ is powered by the Marvell Aldrin3 ASIC, delivering robust hardware-accelerated MACsec right at the link layer. That means seamless encryption and authentication at wire speed — no performance tradeoffs.

It also comes preloaded with AsterNOS, our enterprise-hardened version of open-source SONiC, supporting features like VXLAN, BGP-EVPN, and more. Whether you’re building out a modern data center or securing a high-performance enterprise LAN, this switch checks every box for security, scale, and openness.🔐 Built for MACsec. Ready for the future.

👉 Learn more on our website