Multi-cluster Kubernetes is increasingly essential for enterprise-grade resilience, compliance, and geographic distribution. This guide covers the main reasons to adopt multi-cluster architectures (low latency, HA, compliance, hard multitenancy, M&A), five common topology patterns (active-active, active-standby, cluster per environment/region/tenant, hub-and-spoke), and a deep dive into Cilium ClusterMesh as the implementation mechanism. ClusterMesh uses eBPF-native direct routing without proxies, etcd-based state synchronization via KVStoreMesh, identity propagation across cluster boundaries, global services with load balancing and affinity controls, cross-cluster network policies, and Hubble for multi-cluster observability. Key requirements include non-overlapping Pod CIDRs, node-to-node IP reachability, and consistent datapath modes across clusters.
