In most cases, you should be able to address all computers attached to a network interface on the same private subnet, and leave the default gateway blank for that interface. At this point, note that at the lowest level, every single Ethernet packet that is sent must be sent to a MAC address. This section explains how individual NICs are addressed, how packets are routed on Ethernet networks, and what a typical Ethernet packet transfer looks like. If there is only one default gateway entry for all interfaces, then use its MAC address as contained in the ARP table or send a new ARP request to find the MAC address of the gateway. As you can see, you have the three different Virtual Switch types available – External, Internal, and Private. Note that this is just one possible configuration, any combination of two or more different subnets will work. The Internal Virtual Switch is a type of switch that allows created isolated virtual network environments on which to place Hyper-V virtual machines. Step-By-Step Guide: Getting Started with Dual Ethernet Port Real-Time Controllers, Configuring Software and Hardware Firewalls to Support National Instruments Products. Therefore, it is safer to use the 192.168.x.x range for the private network. The External Virtual Switch is the default switch type that you will see selected when you create a new virtual switch in Hyper-V manager. 255.255.255.192). If all machines follow a rule where all addresses with format 192.168.100.xxx are assumed to be inside the internal network, then it is easy to tell whether communicating with a given IP address requires accessing some other network or not. Once again, no default gateway is needed since neither adapter needs to access an outside network (no gateways are present on this subnet). Receive latest news, updates, and best practices on Virtualization & Cloud, right in your inbox. In the Hyper-V Manager, creating a new Hyper-V Virtual Switch is accomplished in the Virtual Switch Manager found in the Hyper-V Manager utility. If there are multiple default gateway entries, then use the one with the lowest metric (determined by several factors depending on the OS used). This would allow a VM to communicate with other VMs on the Private Virtual Switch as well as with external resources on the physical network. Connecting Hyper-V Virtual Machines to the Physical Network. The virtual interface will be used only for communication between LabVIEW Real-Time and Windows XP. One physical interface will be assigned to Windows XP, and the other to LabVIEW Real-Time. Therefore, each OS will have access to two NICs (the Virtual Ethernet connection and one physical connection). The Address Resolution Protocol (ARP) is used for this. This table shows one possible IP address configuration for the system shown in Figure 5 above. In the case that the MAC address is not known, a computer can send an Address Resolution Protocol (ARP) request to a specified IP address, and the destination machine will reply back with its MAC address. Assume that the physical connections are used to enable communication to the internet from either OS via a corporate network. Many other configurations are also possible, including using DHCP with the remote development PC and LabVIEW Real-Time target (to allow connection with the internet), or using additional NICs in the LabVIEW Real-Time target or remote host computer to connect to the internet. This is needed if you created a guest cluster of Windows Server virtual machines inside of Hyper-V and are provisioning the cluster network for the heartbeat communication between the cluster nodes. It is important to leave the default gateway blank on the NIC #2 settings for the host machine. In this scenario we will work with a Real-Time Hypervisor system that has two physical NICs, and has the internal Virtual Ethernet connection enabled. This TCP/IP configuration is more difficult to set up, especially if the outside networks are not supersets of the local network subnets. Figure 7. Guidelines for Configuring Multi-NIC Systems, Embedded Control and Monitoring Software Suite. Following the guidelines above, we should set a static IP for each of the Virtual Ethernet adapters using a different subnet than is used with the physical adapter on each OS. To ensure that the physical NIC used with LabVIEW Real-Time is on a different subnet than the Virtual Ethernet NIC, we can use an IP address of the form 192.168.1.x with subnet mask 255.255.255.0. By understanding the features and functionality of the various network capabilities found in Hyper-V, administrators can effectively and efficiently control and funnel traffic based on business needs and use cases. Figure 1. In other cases where gateways are attached to subnets that connect with different network interfaces, you can either manually specify network routes (this is an advanced practice) or leave the default gateway blank for all interfaces. Creating the various networks is easily accomplished in the Virtual Switch Manager via the Hyper-V Manager console. The Sender looks at the IP address of the packet, and the subnet mask of its Ethernet interfaces. Again, the virtual machines on this type of Virtual Switch are able to communicate with one another as is the case with the Internal Virtual Switch, but the host is not able to communicate with these VMs. The External Virtual Switch enables connecting virtual machines to the physical network. The key component here is the subnet mask, a group of 32 bits expressed in 4 groups of numbers just like the IP address (e.g. When working with a computer that features multiple network interfaces, you must pay closer attention to networking settings to avoid difficult-to-debug connectivity problems. Figure 2. Because we want both Windows XP and LabVIEW Real-Time to access the internet via the physical NICs, they should be the only adapters that have a default gateway set. Follow these guidelines to ensure the best operation of your multi-NIC system. This can serve the purpose of further scrutinizing traffic if traffic from any of the virtual machines on the Internal Virtual Switch needs to access the physical network for some reason. How does this happen? It allows connecting virtual machines into the virtual network and thereby connecting them into the physical network via the same TCP/IP communication protocols. Microsoft Windows Server Hyper-V networking has powerful capabilities built right into the hypervisor that allows plumbing network traffic between virtual machines and into the physical network in a very granular and manageable way.