Skip to content

Kubernetes Networking Deep Dive

Category: DevOps & Container Orchestration Tags: kubernetes, networking, cni, containers, cluster-management

Pod-to-Pod Communication

  • Each pod gets its own IP address
  • Pods can communicate directly without NAT
  • CNI plugins handle network implementation
  • Flat network space across all nodes

Service Types

ClusterIP - Internal cluster communication (default)

  • Only accessible within cluster
  • Load balances across pod endpoints
  • DNS resolution via service name

NodePort - External access via node ports

  • Exposes service on each node's IP
  • Port range: 30000-32767
  • Good for development, not production

LoadBalancer - Cloud provider integration

  • Provisions external load balancer
  • Cloud-specific implementation
  • Automatic external IP assignment

ExternalName - Maps to external DNS

  • CNAME record for external services
  • No proxying involved
  • Used for service migration

Network Policies

  • Kubernetes firewall rules
  • Default: all pods can communicate
  • Ingress and egress rules
  • Requires CNI plugin support

CNI Plugins

  • Calico - Layer 3, network policies
  • Flannel - Simple overlay network
  • Weave - Mesh networking
  • Cilium - eBPF-based, advanced features