Internal Virtual Networking - Peaking times?

Hi Everyone,

I've got two W2K3 server residing in the same domain, subnet and virtual switch. However there are complaints of poor network performance between the virtual machines. The web developer has a simple app that calls pages and queries on the other server and returns times for each step.

He's telling me that out of a 1.3 Sec average return for the applciation (after running for one day) 1 second of that is the time is the network. Ping times are not granular enough in showing this problem, it mainly returns <1ms with the occasionally 3/4/7 m/s.

CPU and Mem usage on both boxes are 25%. ESX Server is running 23 machines on this vSwitch.

I'm thinking of changing the IP addresses and moving them to their own virtual switch, but I thought the vSwitch was clever enough to do a Point-Point virtual connection and not be bothered by any number of virtual machines on the same switch?

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THe more VMs on a vSwitch the slower the code is. Remember the switch is completely handled by software with no hardware involvement. The more traffic over the vSwitch the more work the vmkernel has to do and there is a possibility of slowness.

I would move the VMs to their own vSwitch just to determine if that was the problem. I would also see if dev VM is using a DNS server outside the vSwitch. Is ALL the network traffic local to the vSwitch or is there a bit outside? You could easily add the Host entry for the target VM into the local machine host table as well to rule out lookup issues.

Also look at the VI Client performance graphs for networking and see what is happening.

Best regards,


Edward L. Haletky
vExpert XIV: 2009-2022,
VMTN Community Moderator
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