The migration to another vCenter instance requires re-assigning the network port group as a part of the migration procedure. Ensure that the correct port group(s) has been selected for all traffic types (including backup, SQL Server Always On Availability Groups replication, etc.).

It’s expected to have many L2 extended (stretched) port groups to be in use for SQL Server workloads. Take care while designing the traffic flow for VMs residing on an extended port group: the default gateway will still be located on-premises. This will cause even the traffic to send to another routed and/or extended port group in VMware Cloud on AWS to be first sent to the on-premises device hosting the gateway and then routed back to VMware Cloud on AWS. The introduction of the proximity routing feature (in limited preview now) will help overcome this situation.

MTU

If a custom MTU size has been configured on the source port group, it’s important to recheck the MTU and the packet defragmentation after migrating to VMware Cloud on AWS. For now, the default MTU size for all inter-SDDC networks is 8950 and from on-premises to VMware Cloud on AWS (for both VPN-based and Direct Access-based connections) is 1500. On a Windows operating system, use the ping -f -l <packet size> command to check the packet size to be transmitted without fragmentation.

NOTE: As VMware Cloud on AWS is quickly evolving, consider checking the release notes to determine if configurable MTU on the DX is made available.

Network Configuration

The following configuration items should be rechecked after the migration:

  • Virtual network adapter – consider using VMXNET3 for all VMs hosting SQL Server workloads
  • RSS/TSO – consider checking the RSS and TSO settings inside of Windows OS and ensure to turn them on. Starting with VMware tools 10.5, RSS is enabled by default on all VMXNET3 adapters but might require the OS level configurations.
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