vSphere dedicated management interface recommended

[rgoerg]

Hello!

I attended a vSphere course recently, where the instructor highly recommended a dedicated management interface. He explained, that for any network interface that is used for vSphere mangement, the vSphere kernel would reserve bandwidth exclusively for the management traffic. In a mixed used vSphere management / VM  traffic interface would never provide full bandwidth for the VMs, even then when there is as good as no management traffic. I couldn't find any description in the vSphere documentation. Is there indeed any kind of reserved management bandwidth?

Reason for this question: I have several servers, each with 1 1GbE interface and 2 10 GbE interfaces; first I wanted to use both 10 GbE-ports in a redundant setup, but now I'm thinking about using the 1 GbE-Interface for the management traffic to make sure that no "unused reserved management bandwith" is wasted on the 10 GbE ports.

Thanks in advance for a feedback!

[DavoudTeimouri · Accepted solution]

Design virtual infrastructure network is related to your virtual machines size and requirements. If you have large VMs that you need to at least 10Gb connection for migation, it's recommended to add 10Gb NIC to VMKernel port-group. With the mentioned hardware specifications, I recommend the below configuration:

If vmnic are like the below:

vmnic1 -> 1Gb

vmnic2 -> 10Gb

vmnic3 -> 10Gb

1. Add vmnic2 as active adapter to vmkernel port-group and add vmnic1 as standby.
2. Add vmnic3 as active adapter to all virtual machines port-groups and keep vmnic2 as standby

BR

Davoud

[rgoerg]

Hello Davoud,

thanks for the feedback. The setup has been realized as suggested.

But just for interest, is there indeed some kind of bandwidth limit on VM Kernel Port interfaces or are they throttled in any way?

Kind Regards

[DavoudTeimouri]

If you are using distributed switch, so you can change resource allocation for system traffic like Management Traffic

[depping]

First of all the amount of bandwidth leveraged by the Management VMkernel is fairly limited. Secondly, there is NO reservation placed of any kind, so I don't know what the instructor was talking about. Thirdly, take a look at your metrics, look at the amount of bandwidth being consumed right now. In most cases, 98 out of 100, when you use a dual 10GbE configuration you can run all traffic types across these links. Most people will not max this out, the only time you come close to maxing it out is when you are doing vMotion's between hosts as vMotion is bandwidth hungry by default.

As mentioned above, you can use a Distributed Switch and set priority for certain traffic types if fairness is a concern. This mechanism however would only come in to play when there is congestion! So if you are running at 30% utilization across those 2 links then Network IO Control wouldn't do anything, and this is not unlikely.