What Is MACsec

6 min readSep 12, 2023



Media Access Control Security (MACsec) is a secure communication technique. It offers Ethernet frame protection and stops devices from processing attack packets by providing identity authentication, data encryption, integrity checks, and replay protection. For Local Area Networks (LANs). This article covers detailed knowledge of MACsec.

Why Is MACsec Required?

On LAN lines, most of the data is often transmitted in plaintext, posing security problems. This renders the LAN vulnerable to assaults, such as stealing or tampering with bank account information. MACsec ensures secure transmission of user service data on a LAN in the following aspects:

  • Data Encryption: MACsec encrypts data using the AES-CMAC technique. Data is encrypted by the sender and sent over the LAN link in ciphertext. The recipient decrypts the encrypted data they have just received before continuing with subsequent operations.
  • Replay Prevention: By default, the receiver discards duplicate or out-of-order data packets to stop attackers from repeatedly delivering acquired messages to attack the network. The order of the packets may change during network transmission of data packets. The replay avoidance method allows for a looser sequence of the data frames. These out-of-order packets can be received if the set window size is not exceeded.
  • Integrity Check: The receiver verifies the data’s integrity to see if it has been tampered with. The Integrity Check Value (ICV) is computed by the sender using the complete data packet and the encryption technique, and it is then added to the tail of the packet. Following packet receipt, the receiver determines the ICV using the data packet’s contents, except the ICV field, using the same encryption process. The derived ICV is then compared to the ICV in the packet. The package is deemed complete and passes the check if it matches. If not, the packet is thrown away.

MACsec Protocols

By encrypting data transfer between Ethernet-connected devices, the security protocol MACsec prevents network data breaches. IEEE first released MACsec in 2006 to safeguard Ethernet networks, and it has since undergone upgrades in 2011 and 2013. Since then, technological developments in the high-performance computing (HPC), mobile, 5G, and automotive industries, among others, have fueled the demand for more security. Even if the MACsec protocol is not brand-new, you may use it right now to secure your Ethernet ports by the most recent specifications, better safeguarding the entire system.

  • MACsec Keying Protocols

MACsec enables data security between the devices by exchanging and verifying security keys. It uses the SAP and MKA security protocols.

  • Security Association Protocol (SAP): SAP is a Cisco-exclusive keying protocol between Cisco switches.
  • MACsec Key Agreement (MKA) Protocol: MKA creates the necessary session keys and controls the necessary encryption keys. Both between switches and endpoints as well as between switches, 802.1AE encryption with MKA is supported.

The creation and management of MACsec security channels and the critical negotiation for MACsec are handled via the MACsec Key Agreement (MKA) protocol. The fundamental ideas involved in the MKA protocol are described as follows:

  • The critical negotiation protocol created and maintains a security association called the Secure Connectivity Association (CA). It is a group on the LAN that uses the same key and critical algorithm suite, and at least two of its members must be MACsec-capable.
  • Secure Connectivity Association Key (CAK) is the crucial CA members employ. Only point-to-point connections are supported by MACsec. In other words, MACsec is established between two devices. Therefore, the same CAK must be used at both ends of a MACsec session. A CA is created by two connected devices using the same CAK.

Comparison To Other Protocols

  • IPSec

The network levels on which MACsec and IPsec operate are different. MACsec operates at layer 2, on ethernet frames, whereas IPsec operates on IP packets at layer 3. As a result, MACsec, rather than IPsec, can secure all DHCP and ARP traffic. IPsec can operate across routers instead of MACsec, which can only be used within a LAN.

User applications can benefit from the security guarantees these standards offer with MACsec and IPsec without changing them.


The OSI’s fifth layer is where SSL/TLS functions. Application changes may be necessary to secure applications, which might be difficult.

The cryptographic layer can also be directly incorporated into the application, which has various benefits. Based on policies, the software is able to independently verify the authenticity and condition of encryption and respond accordingly. End-to-end security can be provided by directly checking such security attributes in the application.

MACsec Advantages

The network security protocol, MACsec, or Media Access Control Security, operates at the OSI model’s data link layer (Layer 2). To guarantee secrecy and integrity, it primarily encrypts Ethernet frames to provide security features for Ethernet networks. The following are some of the main benefits of MACsec:

  • Data Privacy: MACsec encrypts data at the connection layer to protect the privacy of Ethernet frame contents. As the data travels via the network, this stops eavesdropping and unauthorized access.
  • Data Integrity: To ensure the integrity of Ethernet frames, MACsec employs cryptographic methods. This protects against data corruption and unauthorized modifications by ensuring that data has not been tampered with while in transit.
  • Authentication: MACsec supports network device mutual authentication. This implies that the sender and receiver can confirm the other’s identity before creating a secure connection. By doing this, man-in-the-middle attacks can be avoided.
  • Protection Against Insider Threats: MACsec is very helpful for protecting data inside a reliable network. It can defend against internal threats, such as authorized users’ data interception or manipulation attempts.
  • Transparent to Network Applications: Since MACsec runs at the link layer, network applications and upper-layer protocols are unaware of its presence. Applications can use MACsec-protected networks without modification.
  • Low Latency: Low latency is achieved by typically performing MACsec encryption and decryption in hardware. This is crucial for services and applications like audio and video conferencing that demand real-time or low-latency connectivity.
  • Granular Security: MACsec supports the creation of granular security rules. You can secure the parts of your network that must be secured by selectively encrypting particular Ethernet lines or network segments.
  • Scalability: Wide-area networks, campus networks, data center networks, and others can use MACsec. It scales effectively to support various network topologies and sizes.
  • Compliance: Implementing MACsec can assist organizations subject to regulatory compliance regulations, such as those in the financial or healthcare sectors, in adhering to security and data protection standards.

Future of MACsec

Here are some potential trends and directions that could shape the future of MACsec:

  • Increased Adoption: In sectors with strict security regulations, such as finance, healthcare, and government. As businesses realize how critical network-level data security is, its usage may increase further. As businesses realize how critical network-level data security is, its usage may increase further.
  • Enhanced Hardware Support: Switch, router, and network interface card vendors might keep enhancing and incorporating MACsec capabilities into their products. As a result, organizations would find it simpler to apply MACsec without the need for external appliances.
  • Interoperability: It is essential to guarantee interoperability across networking equipment from different vendors. To make it simpler for businesses to install multi-vendor networks securely, industry initiatives may concentrate on further standardizing MACsec’s usage and behavior.
  • Integration with SDN and Cloud: MACsec may need to smoothly connect with cloud-native architectures and Software-Defined Networking (SDN) as these technologies advance. This can entail creating standardized APIs or protocols for controlling and setting up MACsec in dynamic network settings.
  • MACsec limitations: While MACsec (Media Access Control Security) offers robust security for Ethernet networks, it does have certain limitations and considerations that organizations should be aware of when implementing it.
  • Hardware Requirements: As MACsec frequently depends on hardware capability for encryption and decryption, not all network devices can use it. To fully utilize MACsec, organizations need to make a hardware investment.
  • Deployment Complexity: Particularly in large-scale network systems, configuring MACsec can be challenging. Careful planning and cooperation are needed to guarantee that all of the network’s devices are configured appropriately.
  • Key Management: Key management for MACsec deployments is crucial. Organizations must have strong essential management procedures in place to protect the security of keys and properly handle key rotation.


A reliable and well-liked security system for shielding Ethernet networks at the data connection layer is MACsec (Media Access Control Security). Its main goal is to protect data’s confidentiality and integrity while it travels via network lines.

Ultimately, MACsec can be a valuable tool for network traffic security, especially in sectors where data privacy and protection are critical. Organizations should do a thorough risk assessment, consider their network architecture, and keep up with best practices and advancements in MACsec technology to make educated judgments about using MACsec.




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