The core network fabric is based on Ethernet technology. For clusters larger than a single pod, an aggregation layer is required. The aggregation layer can be implemented at either Layer 2 (L2) or Layer 3 (L3). The choice depends on the initial size and planned scaling. Layer 2 is preferred for lower cost and medium scalability.
Layer 3 aggregation is recommended for:
- Larger initial deployments over 36 nodes
- Deployments where extreme scale-up is planned to exceed 250 nodes
- Instances where the cluster must be co-located with other applications in a different rack
The scalability depends on the switches that are used and the oversubscription ratio, and is summarized in Cluster node counts.