Calico is a network plug-in commonly used in Kubernetes clusters, which provides high-performance network solutions for Kubernetes. The main goal of Calico is to provide secure, scalable and high-performance networking for containers and virtual machines. The following is an in-depth understanding of the principles of Calico:
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BGP routing:
- Calico uses the BGP (Border Gateway Protocol) routing protocol to implement network communication between containers.
- Calico agents on each node establish peer connections with agents on other nodes using the BGP protocol and exchange routing information.
- The routing information includes the IP address of the container and the corresponding node information.
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IP pool and IP allocation:
- Calico uses IP pools to manage the range of IP addresses available.
- The IP pool defines the IP address segment that can be allocated, as well as the subnet mask and other network parameters.
- In Kubernetes, each namespace can be assigned one or more IP pools.
- When a Pod is created, Calico allocates an IP address from the corresponding IP pool and assigns that address to the container where the Pod resides.
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Network Policy:
- Calico supports Kubernetes network policies, which can define network access control rules at the Pod and namespace levels.
- Network policies control traffic in and out based on labels and selectors.
- Network policies can restrict traffic from specific IP addresses, namespaces, labels, or other attributes.
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Security and Scalability:
- Calico uses features of the Linux kernel such as network namespaces, iptables, and network isolation for security and isolation.
- Calico also supports encryption and authentication mechanisms for securing communications between nodes.
- The design of Calico enables it to adapt to large-scale Kubernetes clusters and provide high-performance network transmission.
To sum up, Calico is widely used in Kubernetes because it provides high-performance, secure and scalable network solutions. Calico makes communication between containers more efficient and reliable by using the BGP routing protocol, IP pool management, network policies, and underlying Linux kernel functions. Hope this information helps you!