In Kubernetes (K8S), Calico and Cilium are two popular Container Network Interface (CNI) plugins, each of which has unique features and advantages. In the following, we will compare these two CNI plugins in detail and discuss the differences in data handling between Calico's IPIP model and Cilium's VXLAN model.
1. Differences between Calico and Cilium
|
Calico |
Cilium |
Infrastructure |
A pure Layer 3 network solution based on BGP, utilizing the Linux kernel to implement an efficient virtual router (vRouter) to take care of data forwarding. |
Using eBPF (Extended Berkeley Packet Filter) technology to provide fast inter-container communication and network policy implementation. |
Network Protocols |
Uses the BGP protocol for inter-container routing. The Calico agent on each node registers container network information into the BGP routing table and propagates this routing information to other nodes via the BGP protocol. |
Multiple network modes are supported, including tunnel encapsulation protocols such as VXLAN (default) and Geneve, as well as direct routing mode. |
Performance |
High performance, directly realizing inter-container communication through IP routing without additional packet encapsulation and decapsulation, which can save CPU computing and improve network efficiency. |
Also provides high performance network communication, but using eBPF technology may need to run additional programs in the kernel, which has certain requirements on system resources. |
Scalability |
Supports large-scale deployment and good scalability as it dynamically learns and publishes routing information for containers through the BGP protocol. |
Also supports large-scale deployment, but Cilium's multi-tier features (such as service discovery and load balancing) may require more configuration and management. |
Security |
Supports network policy-based security group functionality that enables isolation and secure communication between containers. |
Network policies are also supported and security controls can be further refined through the BPF process. |
Complexity |
The underlying technology is relatively complex and requires a certain level of skill to use and maintain. |
Also requires a certain level of skill, but Cilium's eBPF technology may introduce additional complexity. |
Resource Consumption |
Implementing container network isolation using Linux kernel technology requires a certain amount of system resources. |
Similarly, Cilium may need to consume more system resources to run the BPF program. |
2 Calico's IPIP model
Data processing mode:
- In the IPIP model, Calico implements cross-node IP encapsulation and decapsulation by creating a tunneling device (e.g., tunl0) on each node.
- When a container needs to send a packet to a container on another node, Calico encapsulates the original IP packet in a new IP packet and sends it to the target node through the tunneling device.
- The tunneling device on the target node will decapsulate the received packet and forward the original packet to the target container.
Performance Features:
- IPIP mode does not require additional NAT or Overlay Network, which reduces the process of packet encapsulation and decapsulation and thus improves network efficiency.
- However, due to the IP encapsulation and decapsulation process, it may slightly increase the CPU load.
3. VXLAN model of Cilium
Data Processing Mode:
- In VXLAN mode, Cilium creates a VXLAN device on each node to tunnel communication across nodes.
- Similar to IPIP mode, Cilium encapsulates raw IP packets in VXLAN headers and sends them to the target node through the tunneling device.
- The VXLAN device on the target node will decapsulate the received packets and forward the original packets to the target container.
Performance Features:
- VXLAN mode also provides flexible cross-node communication capabilities and supports more complex network topologies.
- VXLAN may provide better network isolation and security than IPIP mode because it can encapsulate more metadata in the tunnel.
- However, VXLAN may also require more CPU resources to handle the encapsulation and de-encapsulation process.
In summary, Calico and Cilium are both powerful CNI plugins in Kubernetes, and they each have different features and advantages. When choosing, you need to weigh various factors based on specific application scenarios and needs. At the same time, for the differences in data processing between Calico's IPIP model and Cilium's VXLAN model, the choice also needs to be made based on the actual network environment and performance requirements.