Kubernetes pod can't communicate with other pods in the same node-CodePudding

We are using Kubernetes 1.21.7 , Istio 1.11.4 , Flannel 0.14.0 .

kubectl get nodes
NAME     STATUS   ROLES                  AGE    VERSION
k8s-d0   Ready    control-plane,master   204d   v1.21.7
k8s-d1   Ready    <none>                 204d   v1.21.7
k8s-d2   Ready    <none>                 204d   v1.21.7

If pod-a and pod-b are in the same node, for example k8s-d1, they can't communicate (using curl for example). But if I force pods to be in different nodes, they communicate just fine. This issue only occurs in "istio-system" namespace, but it seems it is not an Istio bug (I already tried opening an issue here , but unsuccessful)

CodePudding user response：

I figured out what was missing:

modprobe br_netfilter
echo "br_netfilter" >> /etc/modules-load.d/modules.conf

At same point, I restarted those nodes and br_netfilter didn't load up automatically. Now that it is written in /etc/modules-load.d/modules.conf , it does apply on boot.

Thank you for your support.