Multiple virtual network adapters with their own MAC address and external IP address from the DHCP in Windows

Question

I have been searching for a long time on this forum, and although there are many questions about the topic, I wasn't able to get a concrete solution to the problem.

I want to have multiple IP addresses assigned by DHCP to a single computer using a single network adapter. The purpose of this is that the computer emulates various end nodes involved in a network simulation.

I know that this must be possible, since virtual machine software like VMware can also use a virtual network adapter with its own MAC address bridged with the real network adapter of the host to get an external IP address for the virtual machine from DHCP. Also software like GNS3 can do those tricks, where it is possible to assign an external IP from DHCP to various simulated network nodes.

An often proposed solution is to use a Microsoft loop-back adapter in bridged mode with the real network adapter. However, I don't understand how this is supposed to work. If I install a loop-back adapter and bridge it with the real network adapter, a new 'multiplexor driver' adapter is created called 'Ethernet 3'. This adapter gets assigned an IP from the DHCP, however there is no sign of a second IP address for the virtual network adapter, nor for the real adapter.

I would be really happy if you can help me and explain how the solution of the loop-back adapter is supposed to work. If it can't work that way, I hope you can help me with another solution to achieve the same goal. I have read in many places that it is possible to setup, but nowhere a detailed solution is given that helps me out.

Answer 1

If you want to try to work with virtual networks, it is likely to virtual switches work with various virtual machines. Separately, as a part of the distribution protocol or operating system component or as part of a virtual machine.

Or you can install virtual adapters and assign IP addresses and MAC addresses, but in this case you will have only an additional interface that is suitable for example in the case of the automatic application of RDP server, or to redirect network application activity on the virtual adapter.

Here are some resources to be brought to the attention of some of the features and virtual implementations of switches. Thank you for a good question.

Creating V-switches within the hyper-V environment fails

Hyper-V Network Virtualization and Virtual Switch

Virtual Networking for Hyper-V (Part 1)

Microsoft Hyper-V Networking and Configuration - Part 1

Hyper-V Virtual Networking Maximum Configuration:

• Support For MAXIMUM Remark
• Virtual NICs Per Virtual Machine 12 NICs 4 Legacy and 8 VMBus NICs
• VLAN Unlimited
• Virtual Machines Per VLAN Unlimited
• External Network Virtual Switch Per Hyper-V Server 1 Per Physical NIC
• Internal Network Virtual Switch Per Hyper-V Server Unlimited
• Private Network Virtual Switch Per Hyper-V Server Unlimited
• Virtual Machines Per Virtual Network Switch Unlimited
• Wireless No support for wireless
• VLAN ID Tagging External, Internal
• VLAN ID Tagging On Virtual Machines One per Virtual MAchine

Open Virtual Switch

Supported Platform Open vSwitch can operate both as a soft switch running within the hypervisor, and as the control stack for switching silicon. It has been ported to multiple virtualization platforms and switching chipsets. It is the default switch in XenServer 6.0, the Xen Cloud Platform and also supports Xen, KVM, Proxmox VE and VirtualBox. It has also been integrated into many virtual management systems including OpenStack, openQRM, OpenNebula and oVirt. The kernel datapath is distributed with Linux, and packages are available for Ubuntu, Debian, and Fedora. Open vSwitch is also supported on FreeBSD and NetBSD. The Open vSwitch release in development has been ported to DPDK.

The bulk of the code is written in platform-independent C and is easily ported to other environments.

Answer 2

An often proposed solution is to use a Microsoft loop-back adapter in bridged mode with the real network adapter.

Bridging does the following:

• Network adapters that you bridged are now working on Layer 1 - acting the same as ports on a switch. Call these A and B.

• The new bridge interface models a cable connected to that switch to the bridge interface. This new bridge interface works on Layer 1 and 2.

So:

• You can only assign an IP to the bridge interface, because that's the only thing working on Layer 2.

• A, B and C can see Ethernet frames that pass through from A, B, or C.

I know that this must be possible, since virtual machine software like VMware can also use a virtual network adapter with its own MAC address bridged with the real network adapter of the host to get an external IP address for the virtual machine from DHCP.

VMware installs a network adapter whose driver that takes incoming traffic and moves it to/from a virtual host. GNS3 runs MIPS emulators that emulate Cisco platforms so it has drivers that do the same as well.

I don't think you can separate the Layer 1 and 2 functions of a loopback adapter in Windows-as its typical use is to allow things on a given host to not escape that host.

If you don't want to do virtualization on Windows, try the following:

• Install and use Linux. Linux has much more straightforward DHCP tools, is much more versatile with doing weird networking things (and allows you to get in much more trouble), and you can definitely assign multiple IPs to interfaces without issues.

• Buy some cheap USB-to-Ethernet adapters and connect each to your network.