Hi Teddy092,
Thanks for your reply.
Yes, I tried to transfer data from my real laptop to VM1, VM2, and so on, which are windows server 2016, windows 7pro, CentOS7, or some other VMs. But they have the same speed, up to around 10mbps.
By your suggestion, I checked my vDS configuration and found that the Network I/O Control was enabled. Then, I disabled this function, but the speed is still around 10mbps (or do I need restart the server?). Actually, seems like I don't have any bandwidth limitation config. I just use the default settings of the vDS. I think the vDS seems OK, because when data transferred between VMs, it is really fast. Only when I send data to VMs (when physical NICs are used), it is slow. If I directly send data to the datastore of ESXI host, the speed can reach the limit of the switch interface. The problem may be in the uplinks of the vDS.
You are correct, I really need physical switches with larger bandwidth. I just wonder why this happened and I don't know if it is OK when I use another physical switch.
Thanks a lot!