Unsolved Hyper-V vSwitch, VM, and physical network VLAN question

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Hello, I ran across this practice exam question regarding multiple Hyper-V hosts connected to the "same network" attempting to get the test taker to state what VMs would be able to communicate based on the VLAN settings for each Virtual Switch or VM. I am not quite sure how to answer this one, primarily my confusion is around what happens when you create a vSwitch while specifying a VLAN ID here:

Then create a VM and specify a VLAN ID here:

I can't think of a time when you would ever do this in production.... I would assume that if you were going to enable VLAN tagging for Hyper-V hosts, you would simply leave the vSwitch in its default state without specifying a tag. The Hyper-v host physical network connection would then go to a "trunk" port on the switch where the native VLAN drops into your desired default network segment.

Then when you go to create VMs, you can specify a tag on the VM network adapter which would drop each VM into whatever network segment you needed them to be in.

I can't think of why you would EVER specify a VLAN tag for an entire vSwitch.. In my mind this would force every VM connected to the vSwitch to a particular network segment and further specifying a tag at the VM at that level would just break VM connectivity.

I mean wouldn't just setting the physical network port on the switch to "access mode" of the VLAN you want assigned to the virtual switch essentially accomplish the same thing?

Below is the question and details, hopefully you can help me clear this up!

Regards,
Adam Tyler

You have two Hyper-V hosts named Server1 and Server2 that run Windows Server 2016. Server1 and Server2 connect to the same network. Server1 and Server2 have virutal switches configured as shown in the following table.

You have virtual machines configured as shown in the following table.

All of the virtual machines are configured to have IP addresses from the same network segment. The firewall on each of the virtual machines is configured to allow network connectivity. To which virutalmachines can you connect from VM1 and VM2?

Adam,
On the switch you specify the management switch with the integer input field. On the individual VM's use the integer input field to specify which VLAN on the virtual switch that machine should be a part of. If a company has to comply with certain industry requirements such as out of band management you can have a VLAN for data traffic and a separate VLAN for management traffic.

Thank you,
Cherokee

Thanks for your response Cherokee, but not sure I follow. I'm a CCNA, so I understand what a VLAN is as well as the switching side. I'm also VCP 6 and 6.5, so very familiar with VLAN tagging through VMware infrastructure.

However, this concept of specifying a VLAN tag at the virtual switch vs specifying one at the VM level still has me confused. In the VMware world, the VLAN tag is always specified at the port group.

Maybe examples would help.. In what situations would you specify a tag at the Hyper-V virtual switch vs the guest VM? In what situations would you specify it in both places?

Regards,
Adam Tyler

Cherokee, Okay... Now I feel like an idiot... I just pulled up the lab again and noticed that when creating a Virtual Switch, if you deselect "Allow management operating system to share this network adapter" the VLAN option gets grayed out. So just like you said, this option is simply to force the management OS sharing the NIC to drop into a particular VLAN for managing the host. Not sure why I had so much trouble with that.

So in light of this detail... We can pretty much ignore the vSwitch tagging when it comes to the practice exam question. It only impacts the host connectivity and the question seems to focus on guest connectivity.

So anything connected to vSwitch3 is on an internal switch and won't connect to other guests on other hosts. So focusing on VM7/8/9 they all have different VLAN configs, i would guess they can't connect to each other at all.

So VM1 and VM4 should be able to communicate. They have the same VLAN tag and are both connected to External vswitches.

VM2 and VM5 should be able to communicate.

VM3 and VM6 should be able to communicate.

only detail I am not sure on is if you had all of this connected to simple "access ports", would it still allow VMs with tagged traffic to communicate? No idea.. If not, only the untagged VMs would be able to talk. So VM2 and VM5 because they are untagged. Thoughts?.

Ps.. You might be the only female I know that I could have a conversation with about Virtual Machines and network infrastructure. I'm happily married, the weirdo alarm going off can be silenced. I am pretty sure you are an alien though. How did you get started in IT?

Regards,
Adam Tyler