--- title: IBM Cloud Private description: Example multicluster mesh over two IBM Cloud Private clusters. weight: 70 keywords: [kubernetes,multicluster] --- This example demonstrates how to setup networking between two [IBM Cloud Private](https://www.ibm.com/cloud/private) clusters and then compose them into a multicluster mesh using a [single control plane topology](/docs/concepts/multicluster-deployments/#single-control-plane-topology). ## Create the IBM Cloud Private Clusters 1. [Install two IBM Cloud Private clusters](https://www.ibm.com/support/knowledgecenter/en/SSBS6K_2.1.0.3/installing/installing.html). __NOTE__: Make sure individual cluster Pod CIDR ranges and service CIDR ranges are unique and do not overlap across the multicluster environment and may not overlap. This can be configured by `network_cidr` and `service_cluster_ip_range` in `cluster/config.yaml`. {{< text plain >}} ## Network in IPv4 CIDR format network_cidr: 10.1.0.0/16 ## Kubernetes Settings service_cluster_ip_range: 10.0.0.1/24 {{< /text >}} 1. After IBM Cloud Private cluster install finishes, validate `kubectl` access to each cluster. In this example, consider two clusters `cluster-1` and `cluster-2`. 1. [Configure `cluster-1` with `kubectl`](https://www.ibm.com/support/knowledgecenter/SSBS6K_2.1.0.3/manage_cluster/cfc_cli.html). 1. Check the cluster status: {{< text bash >}} $ kubectl get nodes $ kubectl get pods --all-namespaces {{< /text >}} 1. Repeat above two steps to validate `cluster-2`. ## Configure Pod Communication Across IBM Cloud Private Clusters IBM Cloud Private uses Calico Node-to-Node Mesh by default to manage container networks. The BGP client on each node distributes the IP router information to all nodes. To ensure pods can communicate across different clusters, you need to configure IP routers on all nodes in the cluster. You need two steps: 1. Add IP routers from `cluster-1` to `cluster-2`. 1. Add IP routers from `cluster-2` to `cluster-1`. You can check how to add IP routers from `cluster-1` to `cluster-2` to validate pod to pod communication across clusters. With Node-to-Node Mesh mode, each node will have IP routers connecting to peer nodes in the cluster. In this example, both clusters have three nodes. The `hosts` file for `cluster-1`: {{< text plain >}} 9.111.255.21 gyliu-icp-1 9.111.255.129 gyliu-icp-2 9.111.255.29 gyliu-icp-3 {{< /text >}} The `hosts` file for `cluster-2`: {{< text plain >}} 9.111.255.152 gyliu-ubuntu-3 9.111.255.155 gyliu-ubuntu-2 9.111.255.77 gyliu-ubuntu-1 {{< /text >}} 1. Obtain routing information on all nodes in `cluster-1` with the command `ip route | grep bird`. {{< text bash >}} $ ip route | grep bird 10.1.43.0/26 via 9.111.255.29 dev tunl0 proto bird onlink 10.1.158.192/26 via 9.111.255.129 dev tunl0 proto bird onlink blackhole 10.1.198.128/26 proto bird {{< /text >}} {{< text bash >}} $ ip route | grep bird 10.1.43.0/26 via 9.111.255.29 dev tunl0 proto bird onlink blackhole 10.1.158.192/26 proto bird 10.1.198.128/26 via 9.111.255.21 dev tunl0 proto bird onlink {{< /text >}} {{< text bash >}} $ ip route | grep bird blackhole 10.1.43.0/26 proto bird 10.1.158.192/26 via 9.111.255.129 dev tunl0 proto bird onlink 10.1.198.128/26 via 9.111.255.21 dev tunl0 proto bird onlink {{< /text >}} 1. There are three IP routers total for those three nodes in `cluster-1`. {{< text plain >}} 10.1.158.192/26 via 9.111.255.129 dev tunl0 proto bird onlink 10.1.198.128/26 via 9.111.255.21 dev tunl0 proto bird onlink 10.1.43.0/26 via 9.111.255.29 dev tunl0 proto bird onlink {{< /text >}} 1. Add those three IP routers to all nodes in `cluster-2` by the command to follows: {{< text bash >}} $ ip route add 10.1.158.192/26 via 9.111.255.129 $ ip route add 10.1.198.128/26 via 9.111.255.21 $ ip route add 10.1.43.0/26 via 9.111.255.29 {{< /text >}} 1. You can use the same steps to add all IP routers from `cluster-2` to `cluster-1`. After configuration is complete, all the pods in those two different clusters can communication with each other. 1. Verify across pod communication by pinging pod IP in `cluster-2` from `cluster-1`. The following is a pod from `cluster-2` with pod IP as `20.1.47.150`. {{< text bash >}} $ kubectl get pods -owide -n kube-system | grep platform-ui platform-ui-lqccp 1/1 Running 0 3d 20.1.47.150 9.111.255.77 {{< /text >}} 1. From a node in `cluster-1` ping the pod IP which should succeed. {{< text bash >}} $ ping 20.1.47.150 PING 20.1.47.150 (20.1.47.150) 56(84) bytes of data. 64 bytes from 20.1.47.150: icmp_seq=1 ttl=63 time=0.759 ms {{< /text >}} The steps in this section enables Pod communication across clusters by configuring a full IP routing mesh across all nodes in the two IBM Cloud Private Clusters. ## Install Istio for multicluster [Follow the VPN-based multicluster installation steps](/docs/setup/kubernetes/multicluster-install/vpn/) to install and configure local Istio control plane and Istio remote on `cluster-1` and `cluster-2`. This example uses `cluster-1` as the local Istio control plane and `cluster-2` as the Istio remote. ## Deploy Bookinfo Example Across Clusters __NOTE__: The following example enables [automatic sidecar injection](/docs/setup/kubernetes/sidecar-injection/#automatic-sidecar-injection). 1. Install `bookinfo` on the first cluster `cluster-1`. Remove `reviews-v3` deployment to deploy on remote: {{< text bash >}} $ kubectl apply -f samples/bookinfo/platform/kube/bookinfo.yaml $ kubectl apply -f samples/bookinfo/networking/bookinfo-gateway.yaml $ kubectl delete deployment reviews-v3 {{< /text >}} 1. Create the `reviews-v3.yaml` manifest for deployment on the remote: {{< text yaml plain "reviews-v3.yaml" >}} --- ################################################################################################## # Ratings service ################################################################################################## apiVersion: v1 kind: Service metadata: name: ratings labels: app: ratings spec: ports: - port: 9080 name: http --- ################################################################################################## # Reviews service ################################################################################################## apiVersion: v1 kind: Service metadata: name: reviews labels: app: reviews spec: ports: - port: 9080 name: http selector: app: reviews --- apiVersion: extensions/v1beta1 kind: Deployment metadata: name: reviews-v3 spec: replicas: 1 template: metadata: labels: app: reviews version: v3 spec: containers: - name: reviews image: istio/examples-bookinfo-reviews-v3:1.5.0 imagePullPolicy: IfNotPresent ports: - containerPort: 9080 {{< /text >}} _Note:_ The `ratings` service definition is added to the remote cluster because `reviews-v3` is a client of `ratings` and creating the service object creates a DNS entry. The Istio sidecar in the `reviews-v3` pod will determine the proper `ratings` endpoint after the DNS lookup is resolved to a service address. This would not be necessary if a multicluster DNS solution were additionally set up, e.g. as in a federated Kubernetes environment. 1. Install the `reviews-v3` deployment on the remote `cluster-2`. {{< text bash >}} $ kubectl apply -f $HOME/reviews-v3.yaml {{< /text >}} 1. [Determine the ingress IP and ports](/docs/tasks/traffic-management/ingress/#determining-the-ingress-ip-and-ports) for `istio-ingressgateway`'s `INGRESS_HOST` and `INGRESS_PORT` variables for accessing the gateway. Access `http://:/productpage` repeatedly and each version of `reviews` should be equally load balanced, including `reviews-v3` in the remote cluster (red stars). It may take several accesses (dozens) to demonstrate the equal load balancing between `reviews` versions.