Hyper-V virtualization - Setup and Use in Windows 10  

Cliff S said:

@Kari correct me if I'm wrong.

A virtual switch is basically a bridge between an emulated network adapter on the guest vm and the real physical network adapter on the host computer. A Hyper-V vm has this emulated network adapter and drivers for it and can communicate with the host and other virtual machines emulating an Ethernet connection with an internal or private virtual switch without any whatsoever connection to a host NIC, but as it is an abstract, virtual device, it needs help from a host physical device to connect further to the Internet.

Networking between Hyper-V virtual machines = no external switch needed, you can use a private or an internal switch to emulate an Ethernet connection. However, if you want the virtual machines to connect to the Internet you need to use an external switch which is in its turn connected to a real physical NIC on the host.

Kari

Kari please bear with my, like Wynona said "As you can see, I'm not a Networking Geek either. "
So in less technical terms, it works like a communications hub between VM(s) and host?

Cliff S said:

Kari please bear with my, like Wynona said "As you can see, I'm not a Networking Geek either. "
So in less technical terms, it works like a communications hub between VM(s) and host?

Yes.

As the vm has no physical devices, everything is emulated. CPU, MoBo, GPU, RAM, NIC and so on. Speaking of emulated network adapters, the Internal and Private virtual switches are "the real emulated" devices; they do not need to be assigned to a physical NIC on host to work.

Using an Internal switch on a vm, it can communicate with all other computers (real and vm) in the same subnet. Using a Private switch it can communicate with all other virtual machines on the same host using the same private switch, but it cannot communicate with the host. Both Internal and Private switches have no Internet connection. You can create and use as many Internal and Private switches as you want to.

An External switch is a bit different:

• It needs always to be connected to a physical NIC on host
• You can only have one external switch per one physical host NIC, in most cases the max is two external switches: one for the LAN NIC and another for the WLAN NIC
• You can only create an external LAN switch if the host has a LAN NIC
• You can only create an external WLAN switch if the host has a WLAN NIC
• If your vm is using an external switch to get Internet connection, the vm can only get connected if the NIC on the host is enabled and connected. An example: The host has a wireless WLAN NIC, and your host WLAN is working but not connected = your vm cannot connect to network and Internet. In order to connect the vm using this WLAN external switch to Internet, you need to connect the host WLAN NIC first to the network

In other words, when you open TenForums.com on Edge on your Windows 10 vm running in Hyper-V with an external LAN switch, it sends the order to go to TenForums.com to its own NIC, an emulated virtual device. The virtual NIC contacts the host PC and tells it that "Hi, the vm here. Sorry to bother you but could you please connect me to your LAN NIC, my user needs to open TenForums.com in browser".

The host allows the virtual switch to pass through the traffic, contacts Internet, gets the homepage of TenForums.com, and sends it as asked further to the emulated virtual NIC on the vm, which then passes it through to Edge on your vm.

If the virtual NIC on your vm is the CEO, the external switch is the COO and the host NIC the blue collar staff doing what the CEO originally asked and COO delegated further

Kari

Thanks for explaining in less techy terms. This part gave me the "ah-ha" moment I needed:

In other words, when you open TenForums.com on Edge on your Windows 10 vm running in Hyper-V with an external LAN switch, it sends the order to go to TenForums.com to its own NIC, an emulated virtual device. The virtual NIC contacts the host PC and tells it that "Hi, the vm here. Sorry to bother you but could you please connect me to your LAN NIC, my user needs to open TenForums.com in browser".

The host allows the virtual switch to pass through the traffic, contacts Internet, gets the homepage of TenForums.com, and sends it as asked further to the emulated virtual NIC on the vm, which then passes it through to Edge on your vm.

I just hope you understand that I simplified this quite a lot :)

Kari said:

I just hope you understand that I simplified this quite a lot :)

I just wanted a basic idea on how it works, out of curiosity. Thanks.

Kari said:

Removing an external virtual switch assigned to a wireless physical adapter can be really tricky, in some cases needing a reinstall of Windows before the switch can be re-created.

Sounds like a video to me!

lx07 said:

If so can I act the little packet running around saying "hello, hello, sorry to bother you so much but could I possibly..." Acted like Hugh Grant I think.

lx07 said:

Excellent analogy - it made me smile.