VMware vSAN, a hyper-converged, software-defined storage product, utilizes internal hard disk drives and flash storage of ESXi hosts to create a pooled, shared storage resource. Proper network design is critical for vSAN performance and reliability. Here are some best practices for vSAN network design:

1. Network Speed and Consistency

• Utilize a minimum of 10 GbE network speed for all-flash configurations. For hybrid configurations (flash and spinning disks), 1 GbE may be sufficient but 10 GbE is recommended for better performance.
• Ensure consistent network performance across all ESXi hosts participating in the vSAN cluster.

2. Dedicated Physical Network Adapters

• Dedicate physical network adapters exclusively for vSAN traffic. This isolation helps in managing and troubleshooting network traffic more effectively.

3. Redundancy and Failover

• Implement redundant networking to avoid a single point of failure. This typically means having at least two network adapters per host dedicated to vSAN.
• Configure network redundancy using either Link Aggregation Control Protocol (LACP) or simple active-standby uplink configuration.

4. Network Configuration

• Use either Layer 2 or Layer 3 networking. Layer 2 is more common in vSAN deployments.
• If using Layer 3, ensure that proper routing is configured and there is minimal latency between hosts.

5. Jumbo Frames

• Consider enabling Jumbo Frames (MTU size of 9000 bytes) to improve network efficiency for large data block transfers. Ensure that all network devices and ESXi hosts in the vSAN cluster are configured to support Jumbo Frames.

6. Traffic Segmentation and Quality of Service (QoS)

• Segregate vSAN traffic from other types of traffic (like vMotion, management, or VM traffic) using VLANs or separate physical networks.
• If sharing network resources with other traffic types, use Quality of Service (QoS) policies to prioritize vSAN traffic.

7. Multicast (for vSAN 6.6 and earlier)

• For vSAN versions 6.6 and earlier, ensure proper multicast support on physical switches. vSAN utilizes multicast for cluster metadata operations.
• From vSAN 6.7 onwards, multicast is no longer required as it uses unicast.

8. Monitoring and Troubleshooting Tools

• Regularly monitor network performance using tools like vRealize Operations, and ensure to troubleshoot any network issues promptly to avoid performance degradation.

9. VMkernel Network Configuration

• Configure a dedicated VMkernel network adapter for vSAN on each host in the cluster.
• Ensure that the vSAN VMkernel ports are correctly tagged for the vSAN traffic type.

10. Software and Firmware Compatibility

• Keep network drivers and firmware up to date in accordance with VMware’s compatibility guide to ensure stability and performance.

11. Network Latency

• Keep network latency as low as possible, particularly important in stretched cluster configurations.

12. Cluster Size and Scaling

• Consider future scaling needs. A design that works for a small vSAN cluster may not be optimal as the cluster grows.

By following these best practices, you can ensure that your vSAN network is robust, performs well, and is resilient against failures, which is crucial for maintaining the overall health and performance of your vSAN environment.

Example 1: Small to Medium-Sized vSAN Cluster

1. Network Speed: 10 GbE networking for all nodes in the cluster, especially beneficial for all-flash configurations.
2. Physical Network Adapters:
   • Two dedicated 10 GbE NICs per ESXi host exclusively for vSAN traffic.
   • NIC teaming for redundancy using active-standby or LACP.
3. Network Configuration:
   • Layer 2 networking with standard VLAN configuration.
   • Jumbo frames enabled to optimize large data transfers.
4. Traffic Segmentation:
   • Separate VLAN for vSAN traffic.
   • VMkernel port group specifically tagged for vSAN.
5. Cluster Size:
   • 4-6 ESXi hosts in the cluster, allowing for optimal performance without over-complicating the network design.

Example 2: Large Enterprise vSAN Deployment

1. High-Speed Network Infrastructure:
   • Dual 25 GbE or higher network adapters per host.
   • Low-latency switches to support larger data throughput requirements.
2. Redundancy and Load Balancing:
   • NIC teaming with LACP for load balancing and failover.
   • Redundant switch configuration to eliminate single points of failure.
3. Layer 3 Networking:
   • For larger environments, Layer 3 networking might be preferable.
   • Proper routing setup to ensure low latency and efficient traffic flow between hosts, especially in stretched clusters.
4. Advanced Traffic Management:
   • QoS policies to prioritize vSAN traffic.
   • Monitoring and management using tools like VMware vRealize Operations for network performance insights.
5. Cluster Considerations:
   • Large clusters with 10 or more hosts, possibly in a stretched cluster configuration for higher availability.
   • Consideration for inter-site latency and bandwidth in stretched cluster scenarios.

Example 3: vSAN for Remote Office/Branch Office (ROBO)

1. Network Configuration:
   • 1 GbE or 10 GbE networking, depending on performance needs and budget constraints.
   • At least two NICs per host dedicated to vSAN.
2. Redundant Networking:
   • Active-standby configuration to provide network redundancy.
   • Simplified network topology suitable for smaller ROBO environments.
3. vSAN Traffic Isolation:
   • VLAN segregation for vSAN traffic.
   • Jumbo frames if the network infrastructure supports it.
4. Cluster Size:
   • Typically smaller clusters, 2-4 hosts.
   • Focus on simplicity and cost-effectiveness while ensuring data availability.