docs: add palette communication section PEM-6141

docs/docs-content/architecture/architecture-overview.md

@@ -87,3 +87,29 @@ be optionally downloaded from a self-hosted private repository instead of pullin
 repository.
 
 ![Self-hosted Palette architecture diagram](/architecture_architecture-on-prem-detailed.webp)
+
+### Message Brokers
+
+Palette requires reliable, scalable and secure communication. The internal microservices use a Publish-Subscribe pattern
+implemented with [gRPC](https://grpc.io/) to achieve this. In order to support this communication pattern, a message
+broker service acts as the central hub for message exchange. Palette message brokers are automatically scaled, ensuring
+that a quorum is available for each cluster. The broker system is designed to provide the following functionality.
+
+1. It efficiently distributes incoming gRPC requests across multiple replicas of the message broker to optimize resource
+   usage and platform performance. This capability supports Palette's ability to manage large, enterprise Kubernetes
+   clusters.
+2. It provides high availability by enabling clients to failover to alternative replicas in the case of a pod failure.
+   By default, two replicas of the message broker are created in each cluster.
+3. It automatically adjusts to changes in the number of broker replicas without manual reconfiguration, ensuring that
+   the platform dynamically scales in response to load changes.
+4. It enforces message authentication and security by generating secondary certificates used for broker to broker
+   communication. This provides security in depth.
+
+Any Enterprise and VerteX Palette cluster will have a message broker that you can inspect. First, ensure that you can
+connect to the cluster. Refer to the
+[Access Cluster with CLI](../clusters/cluster-management/palette-webctl.md#access-cluster-with-cli) guide for further
+infomation. You can then view your message broker by executing the following command.
+
+```bash
+kubectl get statefulset msgbroker --namespace hubble-system
+```