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Hyper-V and VLANs

I was excited when I heard that Hyper-V was going to include support for VLANs. What I didn't realize was that there would be some caveats to the deal. If you plan on using tagged VLANs to get support for multiple networks from one physical port, you need to know that Hyper-V works on a one-to-one relationship with interfaces.

To make it all work, you need to create your virtual interfaces (per the software and driver for your NIC) and assign them to the appropriate VLAN. Don't bother putting in any static IP information because as soon as you create a network in Hyper-V to accomodate your VMs, Hyper-V will create another connection on top of the VLAN adapter you've already created. Once this new interface is created, you can enter any static IP addresses there. Additionally, if you don't take into account the extra caveats below, you will have no network connectivity.

EXTRA CAVEATS:
1. Make sure you specify the correct VLAN number in the virtual network.

2. Make sure you specify the correct VLAN number in the network settings for the virtual machine.

Print | posted on Wednesday, April 23, 2008 11:06 AM | Filed Under [ Operating Systems Servers ]

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# re: Hyper-V and VLANs

Hi Ryan
I am currently trying to set up a dell 2950 to support vlan tagged hyper v guest's
I am having difficulty getting the guests to be able to communicate with the gateway.
I have 3 vlans configured on the dell broadcom nic, 1 is for the host machine the other 2 are for the guest networks (DMZ and SECURE), all vlans use the same gateway (fortigate 60b) which has vlan interfaces defined on the connected interface. I know that the gateway is working as expected as i can get connectivity for the host over its vlan.
I have created networks within Hyper V to use the other 2 vlan interfaces created by the broadcom adapter, but any connected guest can not get to the gateway?
Do you have any ideas on what i may be doing wrong?
5/2/2008 3:49 PM | Dwayne Simmiss
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# re: Hyper-V and VLANs

It sounds like you need to double check the settings for the virtual network as well as the VMs. In the virtual network manager, enusure that the "Enable virtual LAN identification" checkbox is checked and the correct VLAN number is entered. In addition, you'll also have to ensure that in the network adapter settings for the VM, you've selected the proper network to bind the virtual NIC to, as well as ensuring that the "Enable virtual LAN identification" checkbox (in the VM settings, not the virtual network settings) is checked. It's dumb, and you'd think the virtual switching built into hyper-v would be able to set a PVID for VMs that don't have that check-box selected, but there it is.
5/2/2008 3:59 PM | Ryan
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# re: Hyper-V and VLANs

Hi Ryan,

I am trying to set up the new forefront TMG on a virtual machine (VM1) that is on a phsyical server called (SRV1).

SRV1 has 6 NIC's, one is used for our internal network and internet access via dsl-broadband (connection 1,NIC1), and another one I have configured to access the fiber optical router (connection 2,NIC2).

So far so good. Both connections work fine.

When I add a virtual network through the Hyper-V console, it creates a connection on top of connection 2, as you well pointed out, but connectivity is limited. Nothing.

The NIC2 on SRV1 has Intel based drivers. It has a VLAN tab in its configuration options. Is there anything here that I should know about or tamper with?

I also tried "Enable virtual LAN identification for parent partition" in Hyper-V but that did not work either. The problem starts once I create a virtual network through Hyper-V.

So what do I have to do to make the VM1 connect to the internet through NIC2 on SRV1?

Any help would be great!
8/18/2008 7:19 AM | Demetrios Tsirlis

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