How data flows between worker nodes in Kubernetes?
I have a single master cluster with 3 worker nodes. The master node has one network interface of 10Gb capacity and all worker nodes have a 40Gb interface. They are all connected via a switch.
I'd like to know if this might create a bottleneck if the data between nodes have to pass through the master node?
In general, I like to understand the communication flow between worker nodes. For instance, a pod in node1 sends data to a pod in node2, does the traffic go through the master node? I have seen the architecture diagram on the Kubernetes docs and it appears to be the case:
source: https://kubernetes.io/docs/concepts/overview/components/
If this is the case, it is possible to define a control plane network separate from the data plane by possibly adding another interface to worker nodes?
Please note that this is a bare-metal on-prem installation with OSS Kubernetes v1.20.
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1 Answer
For instance, a pod in node1 sends data to a pod in node2, does the traffic go through the master node?
No. Kubernetes is designed with a flat network model. If Pod on node A send a request to Pod on node B, the inter-node traffic is directly from node A to node B as they are on the same IP network.
See also The Kubernetes network model