UCS as Master Domain for two separate networks


#1

Hi,
Im installing UCS on HyperV as our new Master Domain Controller. I have two sites linked via fiber optic and would like to keep each one on a different subnet. I thought about giving UCS two NIC cards, each with its own Subnet address and then create two DHCP Pools. Subnets would be on different VLANs. But cant find a howto for doing this… Also I read about something called Shared Networks under DHCP. It seems that this would help me avoid the two NIC thing, but am not sure if it would work. I actually dont have a lab to test this, so trying to be carefull on every option I implement on UCS for not interfiering with actual production enviroment. Hope I’ve explained my problem in an understandable manner, English is not my main language.
Kind Regards,

Juan Martin


#2

Hi,

two LANs should not be an issue at all.
In the end it is your decision how to design your network. If you decide to have two separate ones divided by VLAN (802.1q) or in different physical sections there is no way to offer DHCP services without a second NIC.

You CAN have two IP networks running on the same physical layer but I would absolutely recommend against as this setup is very error prone.

I thought about giving UCS two NIC cards, each with its own Subnet address and then create two DHCP Pools.

This should be fine and would run smoothly. Just be aware as you are talking about a production environment to test outside office hours. Some issues may arise when you have two DHCP servers up and running (previous Win and new UCS).

Anyways, set up two networks in UCS (Blue section), assign DHCP servre service to you UCS, create two subnets and assign the UCS host to each of the subnets. If needed change policy to accept every client instead of only known ones.
You might find further details in our doc.

/CV


#3

Hey,

uhm… If you’re using tagged VLANs on a single physical NIC, you’ll end up with several network interfaces in Linux. Of course you can run DHCP services for each of those VLANs in that case.

m.


#4

You are right. Bad wording. Not clear enough. Should state:

… without two logical NICs

But looks like Hyper-V does not support guest tagging by default.

And, just by experience I would recommend against guest tagging. This makes sense in physical environment, but not in virtual environment where adding additional NICs is just a “click”…

/CV


#5

Hey,

I totally agree with that. Avoiding unnecessary complexity is a Good Thing™. We already have enough mandatory complexity in our sysadmin lives :thinking:


#6

Cristian & Moritz,
Thanks for your replies. If I understood everything, your advice will be having two NICs on UCS. That’s what I thought, but wanted to be sure I wasnt missing something. I’ll try to configure this on my UCS server and let you know how it goes. Just for information, I can tag each NIC with a single VLAN on HyperV and have now this running having my HyperV connected to a switch via trunk port (having multiple subnets inside the HyperV).

Thanks again!

Juan Martin