Multi-cluster - single mesh

Multi-cluster overview

Service Mesh Manager is able to construct an Istio service mesh that spans multiple clusters. In this scenario you combine multiple clusters into a single service mesh that you can manage from either a single or from multiple Istio control planes.

multi-cluster multi-cluster

Single mesh scenarios are best suited to use cases where clusters are configured together, sharing resources, and are generally treated as one infrastructural component within an organization.

Istio clusters and SMM clusters

When you are working with Service Mesh Manager in a multi-cluster scenario, you must understand the following concepts:

  1. Every Istio cluster you attach to the mesh is either a remote Istio cluster or a primary Istio cluster. Remote Istio clusters don’t have a separate Istio control plane, while primary Istio clusters do. To understand the difference between the remote Istio and primary Istio clusters, see the Istio control plane models document.
  2. When you install Service Mesh Manager on a cluster, it installs a primary Istio cluster. This cluster is effectively the primary Service Mesh Manager cluster.
  3. Even if you add multiple primary Istio clusters to the mesh, Service Mesh Manager runs only on the primary Service Mesh Manager cluster (even though some of its components are replicated to the other clusters).
  4. You can deploy Service Mesh Manager in an active-passive model. The active Service Mesh Manager control plane has all components installed on a primary Istio cluster. The passive Service Mesh Manager control plane has only a limited number of components installed on a primary or remote Istio cluster. Only one Service Mesh Manager control plane is active, all other Service Mesh Manager control planes are passive.

This means that when using the Service Mesh Manager CLI (for example, to attach or detach a new cluster), you must run it in the context of the active Service Mesh Manager cluster, even if there are multiple primary Istio clusters in the mesh.

Creating a multi-cluster mesh

Read the multi-cluster installation guide for details on how to set up a multi-cluster mesh.