Preconfigured networks

The two virtual switches VMnet1 and VMnet8 hold special significance. They are assigned to two logical network card drivers which VMware sets up on the host during installation. In the host's network configuration, they appear as "VMware Network Adapter VMnet1 (Host-only)" and "VMware Network Adapter VMnet8 (NAT)". The host regards them as normal network adapters although they are not connected to a physical switch but to a VMnet instead. This way, the host communicates directly with the virtual networks, even without a physical link.

Windows XP, for example, deactivates the network card on the host when the patch cable gets disconnected. A bridged connection would lose contact with the VMs in this case, while a host-only connection will always allow access to the VMs on a laptop, even while travelling.

Traffic through the logical adapters does not have to be isolated. With a suitable routing setup, a LAN client could access the internal test network through the host. Additional logical adapters can be configured at "Host –> Virtual Network Settings –> Host Virtual Adapters", although this should only rarely be required in practical use.

In addition, VMnet1 and VMnet8 operate a virtual DHCP server for the guests and for the host's virtual network card, which also resides in this vSwitch. VMware configures the two logical host adapters using the first IP address in the DHCP range. If guests in VMnet1 or VMnet8 acquire their IP configuration via DHCP, communication with the host works instantly. Users can adjust the internal IP range as required with the little arrow to the right of each VMnet.

Via the "DHCP" tab in Virtual Network Settings, a DHCP server may be added for every VMnet. But beware: in a bridged VMnet, a DHCP server will also serve addresses into the physical LAN. As this may potentially cause network failure, virtual servers should use static IP addresses instead of DHCP.

Another service within VMnet8 is a software router capable of handling "Network Address Translation" (NAT). This enables guests to communicate using the host's identity - similar to the setup behind a DSL router which uses the same public IP for several PCs. To make sure the VMs automatically use the virtual NAT router as their default gateway, the DHCP server passes this setting on in VMnet8.

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