The right encryption solution for a 100G or 400G network depends on two factors: where you want to apply encryption in the OSI model and how much latency you can accept. For high-speed connections, the general rule is that layer 1 encryption offers the lowest overhead, while layer 2 encryption provides more flexibility in more complex network topologies. In this article, we answer the most frequently asked questions about encryption in high-speed networks, so you can make an informed decision.
What are the differences between layer 1 and layer 2 encryption?
Layer 1 encryption encrypts the complete optical signal at the physical level, before data is converted into packets. Layer 2 encryption operates at the Ethernet level and encrypts frames between network devices. The key difference: layer 1 offers the lowest latency and highest transparency, while layer 2 provides more granularity and manageability in more complex networks.
With layer 1 encryption, the signal on the fiber itself is secured. This makes it invisible to attackers who attempt to gain physical access to the cable. All data, including protocol information and metadata, is encrypted. This makes layer 1 particularly suitable for point-to-point connections where maximum confidentiality is required.
Layer 2 encryption, also known as MACsec, operates at the Ethernet frame level. This allows you to apply encryption to specific VLANs or connections within a broader network. This gives more control: you can choose which data streams to encrypt and which not to. This makes layer 2 attractive for organizations with a varied network topology, such as multipoint environments or networks with multiple locations.
How does encryption affect the performance of a 100G or 400G connection?
Modern hardware-based encryption at 100G and 400G has virtually no noticeable impact on throughput speed. The latency added by encryption is below one microsecond with quality solutions. Software-based encryption, on the other hand, can indeed create a bottleneck at such high speeds and is in most cases unsuitable for 100G and above.
The key term here is hardware offloading. With dedicated encryption hardware, the encryption process is handled entirely by specialized chips, separate from the general processing power of the network device. This ensures that encryption reaches line speed, even at 400G. The impact on the network is then negligible.
However, there are points to consider. Encryption adds overhead to each frame or packet in the form of authentication tags and headers. With layer 2 encryption (MACsec), this is typically 32 bytes per frame. On a 400G connection, this effect is minimal, but for systems already operating at the edge of their capacity, it is wise to factor this into your bandwidth planning.
Which encryption standards are suitable for high-speed networks?
For 100G and 400G networks, the most common standards are MACsec (IEEE 802.1AE) for layer 2 and OTN-based encryption for layer 1. Both standards support AES-256 as the encryption algorithm, which is currently considered the industry standard for strong security at high throughput speeds.
MACsec for layer 2
MACsec is widely supported in modern switches and routers and provides point-to-point and point-to-multipoint encryption at the Ethernet level. The standard is scalable and works well in combination with existing network infrastructure. Partners such as Cisco and Huawei support MACsec in their high-speed portfolios.
OTN encryption for layer 1
Optical Transport Network (OTN) encryption is the standard for fiber connections at layer 1. It encrypts the complete transport, including overhead and protocol information. This makes it particularly suitable for long-distance connections and critical infrastructure where even metadata must remain confidential. With an eye on quantum threats, it is also wise to look into quantum-resistant encryption, which uses algorithms that are resistant to the future computing power of quantum computers.
When do you choose point-to-point versus multipoint encryption?
Point-to-point encryption is the right choice when you are connecting two fixed locations and need maximum security and minimum latency. Multipoint encryption is better suited to networks with multiple locations that communicate with each other, such as an organization with multiple offices or data centers connected via a shared network.
With point-to-point connections, the encryption key is known exclusively to the two endpoints. This makes it simpler to manage and inherently more secure. Layer 1 encryption is often the designated choice here, especially for dedicated fiber connections.
Multipoint encryption requires a key management infrastructure that supports multiple endpoints. MACsec at layer 2 is better equipped for this, as it supports key distribution via protocols such as MKA (MACsec Key Agreement). Keep in mind that multipoint encryption brings more complexity in management and configuration. A robust monitoring and management solution is then not a luxury, but a necessity.
What are the most important considerations for encryption in critical infrastructure?
In critical infrastructure, three priorities apply: availability, confidentiality, and demonstrable compliance. Encryption must never come at the expense of network uptime. Therefore, always choose hardware-based solutions with redundancy, and ensure that key management and recovery processes are properly set up in case a device fails.
Compliance is a second consideration. Sectors such as energy, transport, and healthcare are subject to specific regulations regarding data security. By 2026, the requirements from NIS2 and sector-specific legislation will be further tightened. Encryption solutions must demonstrably comply with these standards, including audit logs and certification of the algorithms used.
A third point is the physical security of the fiber connection itself. Encryption protects the data, but an attacker who has physical access to the cable can in theory attempt to tap the signal. Real-time fiber monitoring detects such attempts immediately, so you can respond quickly. Encryption and physical monitoring reinforce each other and together form a complete security layer.
Finally: key management is often the most vulnerable component of an encryption solution. Ensure a clear policy around key rotation, storage, and recovery. In environments where continuity is critical, out-of-band management of encryption equipment is recommended, so that you retain access to management functions even during network issues.
How do you choose the right encryption solution for your network scenario?
Choosing the right encryption solution starts with four questions: at which layer do you want to apply encryption, how much latency is acceptable, how complex is your network topology, and what compliance requirements apply? The answers to those questions together determine whether layer 1 or layer 2 encryption, and point-to-point or multipoint, best fits your situation.
A practical way to structure this:
- Dedicated point-to-point fiber connection, maximum security required: choose layer 1 encryption with the OTN standard.
- Multiple locations, shared network, flexible management desired: choose layer 2 encryption based on MACsec.
- Critical infrastructure with strict compliance requirements: combine encryption with real-time monitoring and out-of-band management.
- Future-proofing as a priority: consider quantum-resistant algorithms alongside the current AES-256 standard.
Want to know which encryption solutions specifically match your network and speed requirements? We are happy to help you map out the right approach, from advice to implementation.
