5 Replies Latest reply on Jun 14, 2019 12:24 PM by mguidini

    Slow Network for VM2 but fast for VM1

    ITTropolis Novice



      I have a server running ESXi 5.5 with (2) VMs:


      VM1: Virtual Machine Version 8, Windows Server 2012 R2 Standard, E1000E network adapter

      VM2: Virtual Machine Version 10 vmx-10, Windows Small Business Server 2011 Stadard, E1000 network adapter


      Both VMs are on the same VMNetwork and both are showing network adapters connected at 1Gbps.


      If I run an Internet speed test from VM1, it comes back around 500 Mbps (customer has fast fiber Internet connection)

      If I run an Internet speed test from VM2, it comes back at only 15 Mbps


      Any ideas as to why VM2 connects to Internet so much slower?


      Thank you!

      Bob H.

        • 1. Re: Slow Network for VM2 but fast for VM1
          daphnissov Guru
          Community WarriorsvExpert

          You should not be using any of the E1000* adapter types with those VMs. Add VMXNET3 and reconfigure the guests to use them. Remove the E1000* adapters.

          • 2. Re: Slow Network for VM2 but fast for VM1
            mguidini Enthusiast

            I believe you should approach this matter in different layers.

            - First as our colleague mentioned, use the VMXNET3 adapter, along with the recommended/updated vmtools version.

            - Second, try to isolate the issue from the host perspective: VMs are in the same host? Going through the same vSwitch/portgroup and vmnics?

            - Even though they are in the same portgroup "VMNetwork" as you mentioned, use the command #esxtop + option "n", and check if the VMs are using the same vmnic.
            - Try different vmnics by migrating the VM to a different host, check the vmnic drivers.

            - Lastly consider that you might be facing an issue outside the VMware world, most probably a physical issue or even a GuestOS issue.


            Hope that helped.



            • 3. Re: Slow Network for VM2 but fast for VM1
              ashishsingh1508 Enthusiast

              I stopped reading after 5.5.


              No longer under support.

              • 4. Re: Slow Network for VM2 but fast for VM1
                ITTropolis Novice



                Both VMs are on same physical host and both are using the same vmnic0.  I added the VMXNET 3 adapter to the slow VM and removed/disabled the E1000 adapter but it's Internet speed is still much slower than the other VM.  The VMXNET 3 adapter shows it's connected at 10GB/s.


                I did notice in vSphere settings for the VMXNET 3 adapter that it said the DirectPath I/O is Inactive and that I need to select Resources tab and to reserve all the guest memory, which I did.  However, it still shows DirectPath I/O as Inactive with message that "The state of the attached network prevents DirectPath I/O."  See attached screenshot.


                Any further ideas?  The slow vm is Windows SBS 2011 and the fast vm is Windows Server 2012 R2.  Could guest OS be the issue?  I don't think so, ya?


                Thanks so much for any insights!

                Bob H.



                VMXNET 3 settings 2.JPG



                • 5. Re: Slow Network for VM2 but fast for VM1
                  mguidini Enthusiast

                  Humm.. SBS 2011, try the following:


                  Check from the windows command prompt, RSS and TCP Chimney offload, if it's enabled, disable both:



                  netsh int tcp show global



                  netsh int tcp set global chimney=disabled

                  netsh int tcp set global rss=disabled




                  Check again the network throughput if it gets any better...These features were supposed to help, but in virtualized environments they are always making trouble..