8.3 Network Considerations
The network is a critical component required for cluster node communication both locally and across sites. In addition to normal network communications, Microsoft Exchange Server in a non-shared disk, high availability solution, such as DAGs, also uses the network for data replication between replicas. With cross data center interconnect replication being key to a successful high availability and disaster recovery solution, the performance of the design is highly dependent on network bandwidth and latency.
Consider the following network configuration guidelines to achieve a robust technical platform with optimal performance:
• Configure appropriate network adapters on the host and virtual machines to separate networks used for different vSphere, virtual machine, and application purposes. For instance, a separate network for data replication, vSphere vMotion, management VMkernel, and so on.
• When using iSCSI at the host level or in the guest’s operating system, the network adapters must be dedicated.
• Use the VMXNET3 paravirtualized NIC with all Windows Server 2012 R2 instances. VMXNET3 is optimized for virtual environments and designed to provide the best performance.
• Enable jumbo frames for the iSCSI and/or vSphere vMotion network.
• Always employ static IP addresses for network interfaces in a Windows Server cluster. Using dynamic configuration through DHCP is not recommended because the failure to renew a DHCP lease might disrupt cluster operations.
• When deploying DAGs across a data center interconnect, a high-speed network must be used for replication traffic. Confirm that the bandwidth and latency of the network is sufficient to support the amount of Microsoft Exchange Server replication traffic