Running Kubernetes on bare metal gives teams complete control over hardware, networking, and performance profiles. However, with this flexibility comes responsibility: designing the networking layer becomes a critical choice with a high impact on your infrastructure.

Among the many options available, Cilium has emerged as a critical CNI plugin for bare metal deployments, not because it’s easy to use, but because of the performance, observability, and policy control it enables.

This article examines why Cilium aligns so well with bare metal environments and explores the deeper strategic reasoning behind choosing it over more traditional CNIs.

Why Cilium is a Natural Fit for Bare Metal

Traditional networking approaches in Kubernetes environments, such as those relying heavily on iptables for network policy enforcement and IPVS for load balancing, were not designed for the scale, agility, or throughput requirements of modern Kubernetes clusters.

As clusters grow, iptables rules can balloon into the tens of thousands, introducing latency, increasing the risk of packet loss, and complicating policy enforcement. 

While IPVS can provide efficient load balancing, the combination of these traditional Linux networking tools still struggles to keep up with the dynamic nature of containerized workloads and their distinct requirements for network policy management and traffic distribution.

Cilium takes a fundamentally different approach by leveraging eBPF to execute programmable logic directly within the Linux kernel. This eliminates multiple layers of abstraction, minimizes context switching, and enables real-time, high-performance packet processing.

On bare metal, where there’s no hypervisor overhead and packets can travel directly between workloads and network interfaces, Cilium’s benefits become even more pronounced:

• Latency-sensitive applications experience fewer hops and lower processing overhead, resulting in improved response times.

• Throughput-heavy workloads benefit from Cilium’s kernel-level efficiency and direct datapath access.

• Scalability improves as Cilium’s identity-aware service and policy management scale linearly with the environment, rather than degrading under complexity.

Beyond performance, Cilium introduces a shift from traditional IP-based controls to identity-based networking. Instead of binding policies to ever-changing IP addresses, Cilium ties them to workload identities derived from Kubernetes labels. 

This model is inherently more resilient in dynamic environments where pods are ephemeral and aggressively rescheduled.

In bare metal setups, where the infrastructure is stable but workloads are not, this identity-first approach significantly reduces the operational burden of managing IP ranges, firewall rules, and NAT translations. The result is a faster, simpler, and more secure networking layer purpose-built for modern Kubernetes deployments.

Why Not Stick with iptables or IPVS?

Conventional networking toolchains were designed in an era when servers were static and networks were flat. While tools like iptables perform adequately at small scales, they quickly run into limitations as rule sets grow. Performance degrades non-linearly, rule ordering impacts latency, and the lack of introspection makes debugging complex and time-consuming.

In contrast, eBPF programs, such as those powering Cilium, are compiled and executed directly in the kernel’s fast path. This approach eliminates the overhead of user-space context switching, enabling high-performance, low-latency packet processing. 

On bare metal servers, where compute and memory resources are fully available and there is no hypervisor overhead, this model delivers substantial performance gains.

The benefits aren’t just technical, they’re operational. eBPF’s efficiency reduces packet loss even under high traffic loads, when traditional CNIs often falter. Observability is also transformed: Cilium’s Hubble provides deep, real-time visibility into service-to-service communication, eliminating the guesswork from debugging and network performance tuning.

As clusters scale, Cilium maintains consistent performance by avoiding the brittle rule chaining and linear slowdown seen with legacy approaches. Its identity-aware model ensures policies scale predictably and securely, making it ideal for dynamic Kubernetes environments that run directly on bare metal infrastructure.

Built-in Observability with Hubble

Bare metal Kubernetes deployments require comprehensive network visibility, as mentioned before.

With Cillium's Hubble, rather than bolting on third-party monitoring stacks, operators gain deep insight into traffic flows at Layers 3, 4, and 7, including policy decisions, dropped packets, and inter-service communication. 

This is not just helpful for debugging; it’s crucial for compliance, auditing, and enforcing Service Level Objectives (SLOs).

For teams running latency-sensitive or regulated workloads, Hubble’s real-time flow visibility can often be the deciding factor between blind troubleshooting and proactive issue resolution.

The Strategic Value of Kube-Proxy Replacement

One of Cilium’s advanced capabilities is its ability to replace kube-proxy, the default Kubernetes component responsible for service routing. While kube-proxy traditionally relies on iptables or IPVS to manage service routing, Cilium leverages eBPF to handle this functionality directly within the Linux kernel.

Why is this significant?

• Reduced Complexity: By eliminating the kube-proxy component, Cilium simplifies the networking stack, reducing the number of moving parts within your cluster.

• Enhanced Performance: Handling service routing within the kernel using eBPF improves performance by eliminating the need for user-space context switching and reducing latency.

• Elimination of Unnecessary NAT Operations: Cilium's approach avoids unnecessary Network Address Translation (NAT) operations, which often complicate debugging and can degrade throughput.

This results in a more transparent and efficient routing model, aligning with the deterministic behavior expected in bare metal environments.

Furthermore, Cilium supports native routing modes that enable direct routing between nodes, bypassing the need for tunneling or encapsulation strategies commonly used in virtualized environments. This direct routing approach reduces overhead and complexity, leading to improved performance.

For bare metal setups, especially those handling large volumes of east-west traffic, these enhancements contribute to lower CPU utilization and reduced packet loss under load, optimizing the overall efficiency of the cluster's networking infrastructure.

Policy Granularity That Matches Security Needs

Bare metal Kubernetes clusters often run mission-critical workloads with strict internal segmentation requirements. While standard Kubernetes NetworkPolicies are limited to L3/L4, Cilium extends this with L7-aware rules, DNS-based policies, and cluster-wide controls.

This enables security teams to move beyond simple source-destination rules and implement policies that govern specific API calls, like allowing only GET requests to certain endpoints. 

It also enables the enforcement of access controls tied to DNS identities, a crucial capability for securing service-to-service communication in microservices architectures.

And because Cilium’s model is based on identities rather than IPs, policies remain valid even as workloads shift, restart, or scale across nodes. This ensures that security remains robust and predictable in even the most dynamic of environments.

Integrating with Existing Network Infrastructure

One of the recurring challenges in bare metal Kubernetes is integrating cluster networking with traditional enterprise routers and switches. Cilium’s support for BGP allows pods and services to be advertised directly to your existing routing fabric.

This eliminates the need for NodePorts or load balancers, enabling seamless east-west and north-south traffic without requiring translation layers. The benefits go beyond just performance. 

By reducing dependency on cloud-native constructs that are often irrelevant in bare metal environments, BGP integration helps lower networking costs, provides more precise control over traffic paths, and simplifies service discovery across hybrid or multi-site topologies.

Native Support with DSR and Maglev

In bare metal Kubernetes deployments, teams often resort to external load balancers to manage traffic distribution. However, this approach can introduce additional latency, increase costs, and create potential points of failure.

Cilium addresses these challenges by providing native Layer 4 (L4) load balancing using eBPF, eliminating the need for external load balancers. Its capabilities include support for Direct Server Return (DSR) mode and the Maglev consistent hashing algorithm.

By operating within the kernel, Cilium's load balancer enables efficient and symmetric traffic routing, which is essential for applications that require low jitter and consistent network paths. Additionally, its stateless request handling reduces CPU overhead, as it eliminates the necessity for connection tracking across nodes.

The implementation of the Maglev algorithm ensures rapid and consistent traffic distribution, even as backend services scale up or down. This approach maintains high availability without requiring manual rebalancing or state synchronization between nodes.

In summary, Cilium doesn't merely integrate with the network: it fundamentally enhances it, offering a more efficient, reliable, and scalable networking solution for Kubernetes environments.

Reach Bare Metal Excellence with Cilium and Latitude.sh

Latitude.sh is a global bare metal cloud platform that provides enterprise-grade infrastructure in advanced data centers worldwide, allowing developers to deploy and manage physical servers globally in seconds via an easy-to-use API and dashboard. 

The fully automated platform combines the performance and security of bare metal with the automation capabilities of the cloud, making it an ideal foundation for running Cilium-powered Kubernetes clusters.

Latitude.sh's global network spans 19 locations across enterprise-grade data centers, providing the high-performance, low-latency foundation that Cilium's eBPF-based networking can fully exploit.

For organizations deploying latency-sensitive applications, AI/ML workloads, or compliance-critical systems, this combination delivers both the predictable performance of dedicated hardware and the operational simplicity of cloud-native networking. 

Latitude.sh offers 24x7 support, dedicated account management, and hybrid cloud connectivity options, ensuring that teams can focus on their applications rather than infrastructure management while Cilium handles the networking complexity.

When Performance Tuning Becomes Strategic

On bare metal, performance tuning is not just a technical task, it’s a strategic advantage. Cilium exposes kernel-level configurations, such as CPU pinning, hardware offload, and buffer sizing.

By dedicating CPU cores to specific networking tasks, teams can minimize interruptions and reduce latency for critical packet flows. Advanced network cards capable of offloading eBPF execution lessen the burden on general-purpose CPUs and increase throughput. 

Meanwhile, tuning buffer sizes at the kernel level can prevent packet drops under bursty workloads, ensuring smoother traffic even at scale.

This control is rarely available, or even possible, in virtualized environments. That’s why bare metal, combined with Cilium, isn’t just fast, but also controllable.

Get the most out of your K8s cluster on Latitude.sh 

Using Cilium on bare metal is all about pushing the boundaries of what Kubernetes can do. 

When you remove the constraints of virtualization and overlay networks, you can now own the whole stack and extract maximum performance, observability, and policy control from every layer of your infrastructure.

Bare metal providers like Latitude.sh offer global deployments with the best developer experience available in the market, helping tech teams gain not just speed, but clarity, consistency, and predictability.

Get started on Latitude.sh today.