WindowsNetworking.com Monthly Newsletter of May 2010 Sponsored by: SolarWinds
Welcome to the WindowsNetworking.com newsletter by Debra Littlejohn Shinder, MVP. Each month we will bring you interesting and helpful information on the world of Windows Networking. We want to know what all *you* are interested in hearing about. Please send your suggestions for future newsletter content to: firstname.lastname@example.org
Networking in Hyper-V is sort of interesting for those who are used to physical networking or how networking is implemented in VMware. With Hyper-V, the guest operating systems never have direct access to the hardware, and the Hyper-V management interfaces control the traffic moving through the physical and virtual interfaces.
Hyper-V has a Virtual Network Manager. The Virtual Network Manager is responsible for creating and controlling virtual switches. There is no limit on the number of virtual switches you can create - depending on the type of virtual network you are working with. For example, external virtual networks are basic on physical NICs, so you can only have the number of external networks that is the same as your number of physical NICs.
The concept of virtual network is an important one for you to understand. Consider a virtual network to be like a switch, but instead of a physical switch, it's a virtual switch. All the virtual machines that connect to the same virtual network switch are, funnily enough, connected to the same switch. Each virtual switch is logically isolated from all other virtual switches. If you want hosts connected to one virtual switch to communicate with hosts on another virtual switch, you can create a virtual router, VPN server, firewall or similar device that you would have on a physical network. It's a good idea to create different virtual switches if you have scenarios where you need to have network isolation similar to what you would have on a physical network, where the different segments are separate by firewalls or some other access control device.
There are three types of virtual networks you can connect to:
A Private Virtual Network is virtual switch that only VMs can connect to. Guest operating systems connected to the same Private Virtual Network can communicate with each other, but they cannot communicate with the Host operating system and the Host operating system cannot connect to the VMs on the Private Virtual Network. Private Virtual Networks are great if you need total isolation from all other Virtual Networks, but can be problematic if you need to copy files to the virtual machines, since there is no connectivity to any physical network or to the Host operating system. In this scenario, you can create a virtual machine that is a firewall or a router, and connect on virtual NIC to the Virtual Private Network and one virtual NIC to the physical network (through an External Virtual Network, which we'll cover in just a bit).
An Internal Virtual Network is similar to a Private Virtual Network in that it is not bound to any physical NIC. The Internal Virtual Network is an isolated virtual switch like the Private Virtual Network, but in the case of the Internal Virtual Network, the Host operating system has access to the guest virtual machines through the Internal Virtual Network virtual switch. However, there is no DHCP-like functionality with this virtual switch (as there is with some instantiations of VMware workstation), so if you want to communicate with virtual machines connected to the Internal Virtual Network switch, you need to assign the virtual NIC assigned to that Internal Virtual Network for the Host operating system an IP address which is valid on the virtual network that you are trying to connect to.
An External Virtual Network is different from the other Virtual Networks because they are associated with physical NICs. You can have one External Virtual Network for each NIC installed on the Hyper-V server. The External Virtual Network switch will actually appear to take the place of the physical NIC on the Hyper-V server - so that if you were to look at the configuration of the former NIC, it would appear to not have any IP addressing assigned to it. Instead, a virtual NIC is added to the Network Connections window and that virtual NIC is connected to the External Virtual Network switch, and it is that virtual NIC that has the IP addressing assigned to it that allows it to communicate with the physical network.
There you have it - a very short course on Hyper-V networks. The type of virtual network you decide to use will depend on your security and isolation requirements. In most cases you'll start with connecting the virtual machines to an External Virtual Network, but then change them over to either a Private or Internal Virtual Network.
Let me know if you have any questions on the types of Virtual Networks used by Hyper-V and I'll answer your questions in the next newsletter.
Quote of the Month - "Two can live for the price of one, for half as long" - Anon.
3. WindowsNetworking.com Articles of Interest
What is Offline Domain Join?
Windows 7 or Windows Server 2008 R2 computers can use the new feature called "Offline Domain Join". This process requires the Windows 7 or Windows Server 2008 R2. This step requires two steps: First the computer account is created or provisioned on the domain controller and the resulting information is stored in the metadata, and then this information is transferred to the joining computer. The workstation then performs the joining part without having the connectivity with the domain controller.
You need to use Djoin.exe on the domain controller to accomplish above. Please use Djoin.exe /? to see the syntaxes.
An example is given below:
For more information about offline domain join, check out this link:
For more administrator tips, go to WindowsNetworking.com/WindowsTips
What is a "core network"? What is a core network in a Microsoft environment? A core network is a collection of network hardware, software, devices and network services that are required to meet your organizations network application requirements.
What are some examples of core network services? How about:
If you're fairly new to the game, or just and to learn more about Windows core network services, then check out the Windows Server 2008 R2 Core Network Guide.
We were sitting around the other day and talking about geeky things and the subject of NTFS came up. If I remember correctly, NTFS was introduced with the first version of Windows NT and has seen a few changes over the years. What we were wondering is if there have been any changes lately to NTFS. Does Windows Server 2008 R2 introduce anything new or cool regarding NTFS?
Thanks! - Homer C.
NTFS is something a geek like you would think about! Seriously, file systems are key to a world class operating system, and NTFS enables Windows Server 2008 R2 to be that world class OS. Some of the major changes you'll find in NTFS with Windows Server 2008 R2 include:
That's a lot of new stuff! If you want to learn the details of these improvements, check out the article What's New in NTFS.