Is it OK for a virtual machine use the same NIC as the host?

I am setting up a new server 2008R2 server with Hyper -V and trying to figure out the NIC assignments.

The server has two built in NICS and a four port add in NIC.  I would like to assign the nics as follows:  The logic being that the onboard nics are best suited to the SAN. By assigning the fourth port to the host and the last VM, until the fourth vm comes online the host gets exclusive use on the nic and when I do need the nic for a vm I will make sure it is one that gets little use.  I am assuming also that the host VM doesn't actually use the nic very often.

Built In NIC A: Connection A to SAN  on seperate ICSI LAN (Broadcom NIC not reccommended for Hyper-V VM)
Built In NIC B: Connection B to SAN on Seperate ISCSI LAN (Broadcom NIC not reccommended for Hyper-V VM)
Add In NIC A:  VM1 windows 2008 SP2 64BIT (Four port Intel NIC recommended for Hyper-V VM)
Add In NIC B:  VM1 windows 2008 SP2 64BIT (Four port Intel NIC recommended for Hyper-V VM)
Add In NIC C:  VM1 windows 2008 SP2 64BIT (Four port Intel NIC recommended for Hyper-V VM)
Add In NIC D:  VM1 windows 2008 SP2 64BIT + Host Hyper-V 2008R2 64BIT (Four port Intel NIC recommended for Hyper-V VM)
PolicyLinkAsked:
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Darius GhassemCommented:
Best Practices you should never have a Virtual Network attached to a Host NIC because of issues you can run into. You should be able to attach multiple VMs to one Virtual Network but if you policy doesn't allow this then I would purchase another NIC. Don't use a virtual network on a Host NIC.
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msmamjiCommented:
Out of curiousity, why do you have so many NICs assigned to the same single VM?
As far as your question is concerned, it is advised not have share the NIC between host (for management) and VMs. I haven't run into problems by doing so.
What surprises me is that you have six NICs and still can't spare one NIC for management.

Regards,
Shahid
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PolicyLinkAuthor Commented:
Sorry,  I didn't fishish editing after a cut and paste. The configuration should say:
Built In NIC A: Connection A to SAN  on seperate ICSI LAN (Broadcom NIC not reccommended for Hyper-V VM)
Built In NIC B: Connection B to SAN on Seperate ISCSI LAN (Broadcom NIC not reccommended for Hyper-V VM)
Add In NIC A:  VM1 windows 2008 SP2 64BIT (Four port Intel NIC recommended for Hyper-V VM)
Add In NIC B:  VM2 windows 2008 SP2 64BIT (Four port Intel NIC recommended for Hyper-V VM)
Add In NIC C:  VM3 windows 2008 SP2 64BIT (Four port Intel NIC recommended for Hyper-V VM)
Add In NIC D:  VM4 windows 2008 SP2 64BIT + Host Hyper-V 2008R2 64BIT (Four port Intel NIC recommended for Hyper-V VM)

The two nics for the san are required so I only have four left to use.  Dedicating one to the host leaves me only three.  It sounds like I should live with the three and share one between two VMs if I end up with four VMs.
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msmamjiCommented:
You don't necessarily need one physical NIC (as a virtual Network) per VM. Infact you can share the one (two, or more) Physical NIC (s) between many VMs.
In you case you can use the three remaining ports for VM communication and one for management of hyper-V host.

Regards,
Shahid
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Darius GhassemCommented:
You need to have one for Hyper-V host management. You can share the same virtual network without multiple VMs.
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